August 2017: Looking Back at Harvey 1 Year Later

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Re: August 2017: Looking Back at Harvey 1 Year Later

Postby srainhoutx » Mon Aug 20, 2018 8:28 pm

Ounce wrote:How dry was the ground that week prior to Harvey landing?


August 2017 had been a very wet month.
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Re: August 2017: Typical August WX/ Tracking The Tropics

Postby srainhoutx » Mon Aug 20, 2018 8:31 pm

The moment my heart sank...

srainhoutx wrote:Overnight Harvey has come back to life from being an open wave in a highly sheared environment to that of what appears to be a developing Tropical Cyclone. Wind shear has collapsed as was expected and it appears an upper level Anticyclone has developed making for ideal conditions for intensification. We will see later today when RECON makes a trek out to investigate if Harvey is as strong as it looks on satellite this morning...if that deep organized convection persists. It serves as a reminder that we never take our eye off a Tropical Disturbance until its dead and gone, particularly when we are in late August and September.

08202017_1245Z_goes13_x_vis1km_09LHARVEY_30kts-1006mb-147N-755W_100pc.jpg


Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Sun Aug 20 2017

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

1. Showers and thunderstorms have increased this morning in
association with the remnants of Harvey. Gradual development of
this system is possible, and it could become a tropical cyclone
once again as it moves west-northwestward across the central and
northwestern Caribbean Sea during the next couple of days.
Interests in northern Nicaragua, Honduras, Belize, and the Yucatan
peninsula should monitor the progress of this system. An Air Force
Reserve reconnaissance aircraft is scheduled to investigate this
disturbance later today.
* Formation chance through 48 hours...medium...50 percent
* Formation chance through 5 days...medium...60 percent

08202017 8 AM EDT two_atl_5d1.png

08202017 12Z Harvey 09L_tracks_12z.png
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Re: August 2017: Looking Back at Harvey 1 Year Later

Postby srainhoutx » Tue Aug 21, 2018 7:10 am

Monday: August 21, 2017 748am

Main focus for the next several days will be the strong tropical wave in the western Caribbean Sea (Ex Harvey) and an approaching cool front.

Upper level pattern is slowly transitioning from summer toward early fall over the region with weakening of the summer sub-tropical ridging which will allow a cool front to approach the area by the end of this week. At the same time this will also allow the tropical wave currently in the western Caribbean Sea to track into the southern Gulf of Mexico and turn toward the NW. Overall late week forecast will hinge on both of these features, but enough confidence is in place that a wet pattern will begin to evolve over the area by Thursday and continue into the weekend.

Tropical Wave (Ex Harvey):

Wave axis continues to move WNW into the western Caribbean Sea, but there has been little to no attempt at the system to try and reorganize. While the wave envelope has expanded to the N over the last 24 hours any weak low level circulation is along the SE flank of the wave and displaced east of the deeper convection. Within the next 24-30 hours the system will be moving inland over the southern Yucatan so the window for any near term development is shrinking. Once in the Gulf of Mexico there is nearly unanimous agreement across the global models that the system will begin to organize and form into a tropical cyclone once again. Track guidance has shifted northward over the last 24 hours due in part to a continued weakness in the ridge that is currently developing over TX and will linger into next weekend. Based on the forecasted steering pattern over the Gulf of Mexico and US Gulf coast by the middle of the week a tropical system in the southern Gulf would likely move NW toward the NE MX/ S TX coast. A stronger system (strong tropical storm or hurricane) would likely turn more NNW and track further northward. Given the current lack of organization and a defined center and the fact that the system will be crossing the Yucatan it is difficult to determine where a new center may form in the Gulf of Mexico and that would have implications on the track.

Late Week Frontal Boundary:

While the tropical system attempts to organize in the southern Gulf, a frontal boundary will drop southward into N TX by Wednesday and into SE TX Thursday and Friday and stall across the area. Moisture will be increasing ahead of this feature as noted by 1.8-2.0 inch PWS over the central Gulf of Mexico currently. This will increase shower and thunderstorm chances Thursday into next weekend. As the boundary stalls, moisture from the tropical system will begin to spread northward and into the frontal zone which will only help to enhance rainfall. Will likely see moisture reach our far outer waters early Thursday and then spread toward the coast Friday depending on how organized the system may become.

Forecast confidence toward the end of the week into next weekend is low given the factors at play and the potential of a western Gulf of Mexico tropical system. Will let the flat to 2 foot seas ride for the offshore waters into Wednesday, but will likely need to start increasing both wind and seas for the late week and weekend periods if current trends hold with a tropical system approaching NE MX/S TX late Friday. Models not currently showing an overly large system, but large enough to potentially bring squalls into our coastal waters. Obviously any adjustment northward of the forecast track this week would bring more impacts into the middle and upper coast of TX.

Monday: August 21, 2017 805pm

Tropical storm or hurricane threat to the TX coast late this week

The strong tropical wave formerly known as Harvey has continued to show increased signs of organization today, but there is no evidence of a defined low level circulation and convection has been decreasing this evening. Surface observations suggest that a broad circulation is found generally ESE of where the deep convection has been found today moving generally toward the WNW or in the direction of the southern Yucatan.

Expect the tropical wave axis to reach the eastern coast of the Yucatan on Tuesday and then emerge into the southern Gulf of Mexico early Wednesday. The well defined upper level low pressure system over the central Gulf of Mexico continues to move westward and will reach the NW Gulf late Tuesday into Wednesday and begin to weaken into a large weakness or shear axis. In other words this feature will break down the remaining ridging over TX and the NW Gulf allowing a trough across the central US by late week to push a frontal boundary deep into the state. This weakness in the ridge appears enough now to turn “Harvey” NW over the Gulf of Mexico with landfall potential from near Tampico, MX to Matagorda Bay, TX. The GFS has become the northern outlier today with a track toward Port Aransas while the CMC is the southern outlier with a track toward Tampico, MX and the ECMWF showing a landfall between BRO and CRP. At this point it is not overly important to focus on individual operational model runs, but instead the trends and the model ensembles. The trends today have been a general more northward track from an early morning consensus in NE MX to a late afternoon consensus over S TX. The CMC, GFS, and ECWMF ensembles are generally aimed at NE MX/S TX.

Much will depend on where a “new” center forms once the wave reaches the Gulf of Mexico early Wednesday. Should the surface center form northward along the wave axis a track toward the middle or upper TX coast would be possible, while a center formation toward the northern Bay of Campeche would likely result in a track toward NE MX/ S TX. It is impossible to determine at this time where any center may form which leads to a low amount of confidence.

One aspect noted in the model trends today is that even with a NE MX landfall the remains of the system get brought northward into SC TX this weekend and collide with the stalled frontal slope over the region. Both the GFS and ECMWF show the outbreak of a fairly significant rainfall event as the remains linger over coastal TX for 3-4 days post landfall and interact with the stalled frontal boundary. This trend can be noted in the “EPS” tracks below showing varying directions and looping motions over TX later in the forecast period indicating a system that is trapped in weak steering flow aloft.

Conditions appear generally favorable for intensification over the Gulf of Mexico with most models showing the formation of a 200mb high pressure cell over the system by the middle of the week helping to vent the surface center and preventing any sort of wind shear. Water temperatures are certainly warm enough to support intensification. The only drawback to intensification will be the 48-60 hours over the Gulf waters, but if conditions are ripe we have certainly seen storms in the past increase 40-60mph in that amount of time. For now will cap the intensity near a strong tropical storm, but a hurricane is certainly possible especially if the system develops quickly after leaving the Yucatan.

Note: NHC has tasked a high altitude mission tomorrow evening across the Gulf of Mexico to sample upper air steering patterns and have 3 USAF missions planned for Wednesday

Tropical Storm or Hurricane watches and warnings may be required for portions of the MX/TX coast as early as Wednesday.

Impacts:

For now will only raise rain chances starting Thursday and hold them high into the weekend and likely will need to closely monitor trends in amounts over the next few days. Will likely have to start pushing up tides starting Thursday, but not sure how high they may go at this point. Seas will almost certainly need to be raised from the flat-2ft currently over the coastal waters. Likely will see 6 ft by Thursday and could likely double that for Friday and Saturday for portions of the TX waters especially south of Matagorda Bay.

Residents along the TX coast should review hurricane preparation plans and be prepared to enact those plans this week
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Re: August 2017: Looking Back at Harvey 1 Year Later

Postby Ounce » Tue Aug 21, 2018 5:28 pm

srainhoutx wrote:
Ounce wrote:How dry was the ground that week prior to Harvey landing?


August 2017 had been a very wet month.

Thanks, Srain!


Eerie that a weak front is coming the same week one arrived before Harvey.
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Re: August 2017: Looking Back at Harvey 1 Year Later

Postby Ptarmigan » Tue Aug 21, 2018 6:54 pm

The forecast models did not handle Harvey too well. They were all over the place.
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Re: August 2017: Looking Back at Harvey 1 Year Later

Postby srainhoutx » Wed Aug 22, 2018 7:19 am

Tuesday: August 22, 2017 741am

***Tropical storm or hurricane threat to TX late this week/weekend***

Residents along the entire TX coast should review hurricane preparation plans today and be fully ready to enact these plans.

Widespread excessive rainfall/flood event increasingly likely Friday-Sunday

Forecast trends overnight continue to suggest that the tropical wave currently crossing the Yucatan will emerge into the southern Gulf of Mexico early Wednesday. The well defined, yet weakening, upper level low now S of Lake Charles will continue to move westward and weaken allowing the continued break down of sub-tropical ridging across TX. This will allow the developing tropical system over the southern Gulf of Mexico to turn NW and NNW toward the TX coast. Nearly all global model guidance is now N of the TX/MX border with landfalls anywhere from Freeport, TX to near Brownsville, TX. The general consensus track is in the region bounded by Corpus Christi on the south and Matagorda Bay on the north. While the model spread is fairly large, the timing is fairly similar and has been for the last 24-36 hours that the system will landfall along the TX coast Friday evening.

The forecast becomes incredibly complex near/after landfall as the upper level steering flow weakens and the system begins to slow down and possibly stall or meander over the region not far inland of the coast. This is the result of the system becoming caught in a “col” region between high pressure to our NW and our NE and a weak frontal zone which will stall Thursday north of I-10. It appears the system will eventually become caught in the frontal trough and slowly creep E/ENE across much of SC/SE TX into SW LA from Friday-Monday. Should this verify as suggested by several forecast models, rainfall and flooding would be “incredible” over the region.

Intensity:
Global models have become aggressive overnight with intensity with both the GFS and hurricane model HWRF showing significant intensification over the NW Gulf Thursday and Friday while the ECWMF, CMC, and UKMET show more modest intensification. It appears nearly everything will align for intensification over the NW Gulf with a 200mb high aloft, very warm SST’s, and possibly the formation of an outflow channel to the south and north of the surface circulation which almost always supports intensification…sometimes rapid. The NW Gulf is certainly no stranger to the formation and rapid intensification of tropical systems and this must be watched very closely once the system enters the Gulf early Wednesday. General consensus of the intensity models bring the system to a minimal category 1 hurricane at landfall along the middle TX coast. Any slowing of the forward motion would only give the system more time to intensify across the NW Gulf….this must be watched very closely.

Impacts:
Impacts appear increasingly likely along the entire TX coast starting as early as Thursday along the lower TX coast and spreading northward on Friday into the middle and upper coast. Following the TVCN track of the major multi model consensus brings tropical storm conditions into the Matagorda Bay region on Friday with hurricane conditions possible over that region Friday night into Saturday morning.

As long as the system does not become more than a category 1 hurricane…the legacy will likely become excessive rainfall and inland flooding. Major models are very aggressive and rightly so with some very impressive rainfall totals given the slow meandering motion near/after landfall. A very large portion of the state generally south of the I-10 corridor could see totals over 2-3 days of 10-15 inches with isolated amounts of 25+ inches. This is a potentially very serious flash flood and river flood threat for a large portion SC/SE TX and the coastal bend. Exact totals will be redefined with time as the track confidence increases

Will not use WW3 guidance on coastal impacts as it is based off the highly aggressive GFS run. Instead will follow the TVCN track which would place at least TS force winds across all of the lower and mid coast waters on Friday and at least the western part of the upper coast waters Friday afternoon and night. Hurricane conditions possible Friday night mid coast into our western waters. Will bump seas to 6 feet Thursday as large long period swells begin to arrive out of the central Gulf which will likely start to push up tides. Will go with 12 feet on Friday with 18 ft over our offshore waters as conditions build to near hurricane force west of Palacios Friday night. Will certainly need to start looking at storm surge threat potential, but without a defined track nor guidance from NHC will just have to wait…certainly could see tides breach the 4.5 ft warning criteria over Matagorda Bay and portions of the upper coast on Friday night into Saturday…but unsure how high they may go as this is very dependent on track and intensity.

Much of these impacts will change over the next 24 hours and this is a very low confidence forecast.

Residents along the TX coast should be closely monitoring weather information at least once a day. Hurricane plans should be in place and ready to be enacted over the next 24 hours.

Tropical Storm or Hurricane watches and storm surge watches will likely be required for portions of the TX coast on Wednesday.


Tuesday: August 22, 2017 338pm

***Hurricane landfall along the TX coast increasing likely Friday or Saturday***

Review hurricane response plans and be fully prepared to enact those plans starting tomorrow.

Discussion:
Satellite images show an increasingly well defined surface circulation across the NW Yucatan currently that will be moving over the southern Gulf of Mexico in the next several hours. The system currently lacks any deep convection near the center with thunderstorms currently displaced to the north along the northern coast of the Yucatan. The circulation is moving toward the NW around 10-12mph and this motion is expected to continue.

Track:
There has been little change in the forecast track reasoning today with a general NW track toward the TX coast expected Wed-Fri. Major global models continue to be in decent agreement moving Harvey into a weakness over the TX coast between a building ridge of high pressure over the SW US and high pressure over the SE US and a trough across the Great Lakes. Landfall locations continue to shift around with each model run, but the main consensus continues to be in the region between Corpus Christi and Matagorda Bay.

The steering flow nearly collapses as Harvey reaches the coast and expect a decrease in forward speed as the system moves inland over the coastal bend on Friday night. This is where the forecast becomes greatly complicated as Harvey becomes trapped in a weak steering regime across SC/SE TX into the early portion of next week. The system is effectively left to meander and loop somewhere in the region bounded by Matagorda Bay, Austin, and Galveston. Eventually it appears Harvey will slowly track E to ENE either along the coast or inland of the coast across SE TX Saturday-Tuesday.

Intensity:
Conditions appear favorable for intensification of Harvey up to landfall on the TX coast. All parameters appear to be satisfied including warm SST’s, 200mb high pressure over the center of the system, potential dual outflow channels to the NE and SW of the center. It is possible that a period of rapid intensification could occur as Harvey nears the middle TX coast on Friday. Intensity forecast skills are poor especially when dealing with rapid intensification…this aspect will need to be monitored closely over on Thursday and Friday as Harvey approaches. Current coordinated NHC/WPC positions bring s minimal hurricane into the coast in the reach between Corpus and Port O Connor Friday evening.

Impacts:
Without any sort of NHC track guidance the following impacts are based on the TCVN (consensus model track) with storm surge forecast off ET surge, but I have cut it back some based on the latest GFS run. Have also taken a good look at the cat 1 SLOSH output for a NW tracking hurricane into just W of Matagorda Bay and merging those values with ET surge seems to be a good compromise at the moment. Additionally, there has been some coordination with the storm surge unit at NHC via the local WFO today. Rainfall has been coordinated with local WFO’s and WPC…mainly to encourage WPC to raise expected totals.

Rainfall:
I have never seen the GFS and ECWMF models forecasting such a large amount of rainfall over such a large area. Widespread rainfall amounts of 8-12 inches is likely with isolated totals of 20 inches or more. River, creek, bayou, and flash flooding would be a given with totals of this magnitude. Unlike so many of the flood events we deal with across this area where isolated areas get the very high totals…the potential here is for a very large area to see excessive amounts of rainfall.

Widespread: 8-12 inches (all areas)

Isolated: 20 inches +

Storm Surge:
Will start to see increasing tides Thursday afternoon and possible we may hit 3.0 ft total water level Thursday afternoon/evening especially Matagorda Bay southward toward Mustang Island. Will go with total water levels Friday rising to 4.0-5.0 feet along all of the upper and middle coast and likely nearing 6.0 feet around Matagorda Bay. 4.5 feet is our critical warning threshold along much of the upper coast for the start of impacts and think we will hit those levels on Friday especially Matagorda Bay. Overwash and coastal flooding appears likely Friday from Palacios southward including Matagorda Island and along the west side of Matagorda Bay.

Tides will increase Friday night across the coast NE of Palacios as SE winds pile water and wave action onto the coast. Will build to 4.0-5.5 feet Friday night along Brazoria, Galveston, and SE Harris coast with overwash likely on the west end of Galveston and Bolivar. With the continued onshore flow well into Saturday and Sunday tides will only worsen over the weekend as water becomes trapped in the bays…especially the western side of Galveston Bay. Certainly looking at potential coastal flooding around Clear Lake, Kemah, Seabrook, Galveston Island, Bolivar on Saturday…but don’t want to go much more than 5.5-6.0 feet total water level at this time as a lot of factors are in play.

Matagorda Bay: 4-5 ft (Friday/Saturday)

Galveston Bay: 4-5 ft (late Friday/Saturday)

Gulf Beaches: 4.5-5.5 ft (Friday/Saturday)

Onset of 3.0 ft total water level rise Thursday afternoon/evening

Winds:
A lot of uncertainty with this aspect.

Tropical storm conditions (40mph sustained) will begin to reach the middle coast on Friday around midday and spread inland into the evening hours. Will bring Jackson, Matagorda, Calhoun, and Wharton Counties into the TS force winds by Friday evening and build to hurricane force (75mph sustained) over Calhoun County southward to near Corpus Friday night. Could be very near hurricane conditions into much of Matagorda Bay Friday night and possibly Matagorda County with tropical storm conditions up to Galveston by Saturday morning. If the system does in fact turn NE/ENE just inland this will bring tropical storm and potential hurricane conditions across a larger portion of SE TX.

Should get better details on this tomorrow if NHC starts advisories.

Actions:

Hurricane plans should be fully prepared to be enacted on Wednesday including fully stocked hurricane kits.

Ride out teams should be notified and activation of COOP’s is recommended starting Wednesday.

Preparations should include the potential for loss of power and prolonged excessive rainfall and flooding along with prolonged high coastal tides. Some areas near the coast may become cut-off as early as Friday.

Significant rises on area rivers, creeks, and bayous is a real threat and residents living in flood prone areas should be prepared for rising water and potentially significant flooding.

Note:
GIV upper air mission is underway over the Gulf of Mexico which should help firm up model guidance for the 12Z runs on Wednesday…some of the samples may get into the 00Z runs this evening.

USAF/NHC have several C-130 53rd missions planned into Harvey starting tomorrow and this will continue up to landfall…so there will be nearly constant checking on intensity trends.

Tropical storm, hurricane, and storm surge watches and/or warnings may be required for portions of the TX coast on Wednesday
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Re: August 2017: Looking Back at Harvey 1 Year Later

Postby srainhoutx » Wed Aug 22, 2018 11:17 am

Eric BlakeVerified account @EricBlake12 · 48m48 minutes ago
A year ago today I (with input from other NHC colleagues) wrote the most strongly worded Tropical Weather Outlook of my career- it mentioned the possibility of hurricane-force winds and storm surge in Texas before #Harvey regenerated. That’s very rare in that product!

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Re: August 2017: Looking Back at Harvey 1 Year Later

Postby srainhoutx » Fri Aug 24, 2018 7:49 am

One year ago this morning we awoke to a rapidly strengthening Harvey. It was also the day we realized that the earlier QPF forecasts were likely too low and talk began within the Weather World of a potential Catastrophic Flood Event where many locations would possibly see 40 to some isolated 60 inch amounts over the coming weekend into early the next week.

08242017 1230Z latest.jpg

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Re: August 2017: Looking Back at Harvey 1 Year Later

Postby Texaspirate11 » Fri Aug 24, 2018 8:29 am

I'll never forget this hurricane.
Just because you're disabled, you don't have to be a victim
Be Weather Aware & Prepared!
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Re: August 2017: Looking Back at Harvey 1 Year Later

Postby srainhoutx » Fri Aug 24, 2018 8:36 am

Thursday: August 24, 2017 555am

Hurricane Warning is issued from Port Mansfield to Matagorda including Matagorda Bay

Tropical Storm Warning is issued Matagorda to High Island including Galveston Bay

Storm surge Warning is issued from San Luis Pass to Port Mansfield including all inland bays and inlets

Preparations to protect life and property should be rushed to completion in the hurricane warning area

Discussion:
USAF mission showing the pressures are falling down to 995mb. New plane is on the way…but the convective cloud pattern is well organized this morning with a massive explosion of deep convection over the center of the system. Intensification is underway and there appears to be little to stop it until landfall. Plane also found some winds stronger than 40-45mph, but these were sampled on the last pass and the new inbound mission will help with the current intensity.

Intensity:
I am very concerned with rapid intensification over the next 36 hours as Harvey approaches the coast. Conditions are very favorable with warm temps of 85-88 degrees and a building 200mb anti cyclone over Harvey. NHC has pushed the forecast to 85mph and that may not be enough. SHIPS intensity guidance continues to show high values of rapid intensification over the NW Gulf of Mexico. A category 2 hurricane impact is possible.

Track:
Harvey has been drifting erratically overnight with USAF mission fixes showing a northward motion, but this may be more the center getting better organized. Harvey is at the western edge of the sub-tropical ridge over the eastern Gulf of Mexico and a general NW to NNW track toward the middle TX coast will begin today. Major guidance models agree with the track reasoning through landfall bringing a hurricane into the middle TX coast around Rockport/Port Aransas.

After landfall the steering flow completely collapses and Harvey is left to stall and meander over the coastal bend. A glimmer of hope last night was that Harvey would be able to move WSW/SW after landfall decay over SW TX/NE MX, but all guidance overnight now has Harvey looping back SE and toward the Gulf of Mexico early next week and then tracking along the upper TX coast. This part of the forecast is very uncertain and there is really no steering at all from Saturday-Monday. Harvey will be effectively like a marble on a flat table and only a small influence will nudge it in one direction or the other.

Impacts

Rainfall:

Dangerous and life threatening rainfall and flood event becoming likely as Harvey stalls over the region.

Widespread rainfall totals of 10-15 inches with isolated amounts of 20-30 inches will be possible. It goes without saying that these amounts over such a large area will be devastating.

Onset of rain bands along the lower coast late tonight spreading N into the mid coast midday Friday and the upper coast Friday night. Widespread banding and core rainfall will continue through the entire weekend and into next week mid and upper coast.

Wind:

I am very concerned with the potential for rapid intensification as Harvey nears the coast. Wind forecast below may need to be bumped up as trends show today

Galveston to Matagorda: 40-50mph Friday night/Saturday (onset after 800om Friday)
Matagorda to Corpus Christi: 75-90mph Friday night (onset early Friday evening)

Hurricane force winds will spread inland over Matagorda Bay and SC TX Friday night into Saturday impacting a large area from Victoria SSW to SW of Corpus Christi. Harvey will be an intensifying hurricane at landfall (the last hurricane like this on the mid TX coast was Claudette 2003) which brought strong damaging winds inland. Given the favorable upper air pattern aloft and the fact that Harvey will stall close to the coast winds will only slowly subside and in fact Harvey may still be a tropical storm on Sunday over 48 hours after landfall.

Storm Surge:

Will have to raise the surge values in Matagorda Bay to 3-5 feet above ground level especially NW head of Lavaca Bay. Most of this remains marsh areas, but some impacts to the low lying areas around Port Lavaca, Indianola, and Port O Connor are likely. Also starting to see some increasing values in San Antonio Bay and the Seadrift and Tivoli areas into the lower Guadalupe River.

Also starting to see more surge around Matagorda and the mouth of the Colorado River…up to around 3 feet above the ground. Possible overwash of Matagorda Island at these levels

Down the coast looking at isolated areas of 2-4 feet above ground level into portions of Corpus Christi Bay and Aransas, Refugio, and San Patricio coastal areas.

Storm surge values for Galveston Bay should be 3ft or lower.

Will need to watch the intensity trends today as some of these values may need to be raised more from Matagorda southward…residents in those low lying coastal evacuation zones in the hurricane warning area should be ready to leave with little notice from Matagorda to Corpus Christi

Actions:

Preparations for the landfall of a hurricane MUST be underway in the hurricane warning area

Shutter or board windows

Prepare for widespread power outages (Matagorda to CRP)

Secure outdoor objects

Move small craft to safety and secure boats in ports

Entire region should be preparing for a prolonged inland flood threat that could last for many days.




Thursday August 24, 2017 719am
USAF mission showing tremendous pressure falls in progress with Harvey. Pressure is down to 985mb which is a 10mb fall in 1 hr. Flight level winds up to 62kts and plane shows the formation of a northern eyewall.

Maximum sustained winds have increased to 60mph…maybe a hurricane by later this morning

Rapid intensification is in progress…NHC will likely increase landfall intensity to cat 2 at 1000am, it is possible this may reach major hurricane status.

Preparations to protect life and property in the hurricane warning area MUST be rushed to completion.

Coastal residents in hurricane evacuation zones from Matagorda to Corpus need to be ready to leave immediately.


Thursday August 24, 2017 1009am

Major hurricane forecasted into the middle TX coast.

Life threatening storm surge likely middle TX coast

Rush preparations to protect life and property to completion in the hurricane warning area.

Coastal residents in Matagorda Bay southward to Corpus be prepared for immediate mandatory evacuations….heed all advice from local emergency officials.

08242018 Jeff 1 untitled.png

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Thursday: August 24, 2017 1056am

***Major hurricane event for the TX coast***

Preparations to protect life and property MUST be rushed to completion in the hurricane warning area

Life threatening storm surge likely Corpus Christi to Sargent TX including all Matagorda Bay.

This will be the most significant hurricane impact on the TX coast since Hurricane Ike

Winds:

Corpus Christi to Port O Connor: 110-120mph g 130mph
Port O Connor to Palacios (Matagorda Bay): 80-90mph
Palacios to Galveston: 55-60mph
Galveston to High Island (Galveston Bay): 40-45mph

Storm Surge:

Values below are listed as total water levels above ground level:

Mustang Is to Sargent: 6-10 ft
Sargent to San Luis Pass: 5-7 ft
San Luis Pass to High Island: 2-4 ft

Note: higher values near 12-15 feet may occur at the NW head of Lavaca Bay and San Antonio Bay.

Significant storm surge inundation and destructive wave action is likely from Sargent to Mustang Island including: Rockport, Port Aransas, Seadrift, Port O Connor, Matagorda,

Heed all local emergency management recommendations…if you are told to evacuate…leave immediately. Evacuation decisions for areas between Corpus and Matagorda Bay are being made at this time.

See link below for forecasted surge inundation:

http://www.nhc.noaa.gov/refresh/graphic ... n#contents

Rainfall:

Will maintain the widespread 10-15 inch totals with isolated 20-30 inches possible. Stalled system around Matagorda Bay for 2-3 days could result in devastating rainfall totals over a large area of SC/SE TX and the coastal bend.


Thursday: August 24, 2017 1251pm

Harvey is now a hurricane with 80mph winds

Mandatory Evacuation: all Calhoun County (effective immediately)

Port Aransas/Aransas Pass: Mandatory evacuation (effective immediately)

Mandatory Evacuation: all San Patricio County (effective at noon today)

Mandatory Evacuation: City of Ingleside (effective immediately)

Voluntary Evacuation: all Jackson County (effective immediately)

Voluntary Evacuation: western Nueces County

Voluntary Evacuation: all Victoria County

Voluntary Evacuation: all Bolivar Peninsula

Voluntary Evacuation: City of Corpus Christi (effective at noon today)

Heed all advice given by local emergency officials. If you are told to evacuate….leave immediately.

Additional evacuation orders are possible


Thursday: August 24, 2017 156pm

Harvey continues rapid intensification…pressure down to 979mb and winds sustained to 85mph.

100pm forecast now brings strong cat 3 (125mph sustained) into the middle TX coast…cat 4 is possible.

This is a life threatening hurricane and rainfall situation.

Preparations to protect life and property MUST be rushed to completion.

Numerous evacuation orders are now in effect….follow orders immediately….persons in the hurricane warning area need to heed recommendations by local officials.

***Storm Surge warning extended to High Island…not including Galveston Bay***

New Evacuation Orders:
West end Galveston Island (voluntary evacuation order in place)

Mandatory Evac: City of Portland

Will get new impacts out after the 400pm NHC advisory package…biggest change at 100pm:

Raise storm surge values from Sargent to Jamaica Beach: 5-8 ft


Thursday: August 24, 2017 456pm



***Major hurricane impact into the TX coast likely Friday night***

***Preparations to protect life and property MUST be rushed to completion in the hurricane warning area***

Hurricane Warning in effect from Port Mansfield to Sargent (extended NE from Matagorda)

Tropical Storm Warning in effect from Sargent to High Island

Storm Surge Warning from Port Mansfield to High Island

Discussion:
USAF plane continues to show pressure falls in Harvey now down to 976mb…that is over 25mb since 400am this morning…which is rapid intensification. The convective pattern continues to look well organized with deep convection wrapped completely around the center and a well formed eyewall with good banding. There is nothing to prevent intensification up to landfall.

Intensity:
Trying to keep up with the intensity changes today has been like chasing running water…looking at a solid (mid to strong cat 3 into the mid TX coast) with sustained winds of 125mph. Could be slightly stronger (130-135mph) which would be cat 4. We are splitting hairs on the damage potential which is extreme. Entire structures will fail under these types of wind loads (Rockport to Port O Connor)

Track:
There has been little change in the track reasoning today which will bring a devastating hurricane to the TX coast. Latest ECMWF run is even slower and now stalls Harvey on the coast or just offshore. NHC guidance keeps it moving just inland. We must get the center inland or the storm will not weaken. Latest reasoning also turns Harvey ESE/E and track it up the upper TX coast to be located over Galveston next Tuesday.

Impacts:

Storm Surge:

Storm surge inundation (will update to the 400pm ADV at 530pm)

http://www.nhc.noaa.gov/refresh/graphic ... n#contents

Life threatening storm surge is likely along the coast from north of Corpus Christi to Sargent including Matagorda Bay.

I want to be very clear on the storm surge levels as there is some confusion on what these numbers are indicating.

All the numbers listed below are ABOVE THE GROUND, not above sea level

Mustang Island to Sargent including Matagorda Bay: 6-12 feet (above the ground)
Sargent to Jamaica Beach: 5-8 ft (above the ground)
Jamaica Beach to High Island: 2-4 ft (above the ground
Galveston Bay (Seabrook, Shoreacres, Nassau Bay, Kemah, San Leon: 2-4 ft (above the ground)

Rainfall:

Dangerous and life threatening flood event is likely over a very large area

Flash Flood Watch issued until further notice

Widespread rainfall amounts of 10-20 inches with isolated totals of 30 inches is possible. Clearly this will be a potentially catastrophic flooding event for a large portion of SC/SE TX and the coastal bend. Major flooding of the Harris County bayous and creeks is very possible along with major to record flooding on some of the rivers over SE TX and the coastal bend.

Winds:

Devastating core winds within the eyewall of Harvey will impact areas from Rockport to Port O Connor

Rockport to Port O Connor: 120-125mph g 130+

Matagorda Bay: 110-115mph g 125

Port O Connor to Sargent: 80-90mph

Sargent to Surfside: 50-60mph

Harris County including Galveston Bay: 45-50mph

The following impacts are expected from Matagorda to Rockport:



- Structural damage to sturdy buildings, some with complete roof

and wall failures. Complete destruction of mobile homes. Damage

greatly accentuated by large airborne projectiles. Locations

may be uninhabitable for weeks or months.

- Numerous large trees snapped or uprooted along with fences and

roadway signs blown over.

- Many roads impassable from large debris, and more within urban

or heavily wooded places. Many bridges, causeways, and access

routes impassable.

- Widespread power and communications outages.



Evacuation Orders:

Mandatory Evacuation: Brazoria County (Gulf of Mexico to the Intracoastal Canal)

Mandatory Evacuation: all Calhoun County (effective immediately)

Mandatory Evacuation: Matagorda County (South of FM 521 and FM 2611 in Sargent), all areas S of FM 521 in Matagorda County, all areas south of Business 35 W of Palacios. All persons under age of 18 must leave the evacuation area

Port Aransas/Aransas Pass: Mandatory evacuation (effective immediately)
Mandatory Evacuation: all San Patricio County (effective at noon today)
Mandatory Evacuation: City of Ingleside (effective immediately)
Mandatory Evacuation: All Refugio County (effective immediately)
Voluntary Evacuation: all Jackson County (effective immediately)
Voluntary Evacuation: western Nueces County
Voluntary Evacuation: all Victoria County
Voluntary Evacuation: all Bolivar Peninsula
Voluntary Evacuation: City of Corpus Christi (effective at noon today)

08242018 Jeff 3 untitled.png

08242018 Jeff 4 untitled.png

Note new color scale for rainfall forecast being created since the old graphic was never intended to exceed 25 inches of rainfall
Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey

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