November 2015: Ending Cold & Rainy

General Weather Discussions and Analysis

Re: November 2015: Thanksgiving Holiday Outlook

Postby Texaspirate11 » Tue Nov 24, 2015 10:55 am

I hope everyone remains safe this Thanksgiving holiday
Thank you for this wonderful forum, I am so grateful for this place.
Be blessed and safe everyone.
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Re: November 2015: Thanksgiving Holiday Outlook

Postby unome » Tue Nov 24, 2015 11:55 am

http://www.wunderground.com/blog/JeffMa ... ench-texas

Late-Season Tropical Storm Sandra Could Strike Mexico and Drench Texas
By: Jeff Masters and Bob Henson , 4:05 PM GMT on November 24, 2015

part of it:

Sandra may complicate heavy rain threat over Southern Plains
The biggest impacts from Sandra may occur from Texas to Arkansas, where a prolonged heavy rain episode late this week seems likely to be enhanced by Sandra’s remnants. A strong upper-level low settling over the U.S. Southwest will help pull Sandra northeastward, and the storm’s moisture will flow atop a very shallow cold air mass that will spill across the Southern Plains later this week. Such setups involving Eastern Pacific hurricanes are notorious for giving the region some of its heaviest rains on record, but they are far more typical of September or October than late November. Localized flooding may become a major travel headache, as rainfall totals of 3-8” are expected from Thursday through Sunday over central and north Texas, southeast Oklahoma, southern Missouri, and northwest Arkansas (see Figure 2 below). These rains will fall over areas that have been doused repeatedly over the last few months. With 50.75” of rain for the year through Tuesday morning, Dallas-Fort Worth area may well break its all-time annual precipitation record of 53.54” (set in 1991) before November is done.

On the northwest edge of the heavy rain swath, there should be a parallel strip with low-level temperatures cold enough for mostly light but widespread freezing rain, sleet, and/or snow, with an initial round from Thanksgiving Day into Friday and perhaps a second batch over the weekend as another lobe rotates around the sprawling upper-level low. Frozen precipitation is most likely from the Texas Panhandle and northwest Oklahoma across much of Kansas to eastern Nebraska.


and, from

http://www.wunderground.com/blog/SteveG ... trynum=407

Stormy Thanksgiving / Potential Flash Flooding and Blizzard Conditions for Texas / W
By: Steve Gregory , 10:39 PM GMT on November 23, 2015

a bit of it:

While forecasts so far in advance have limited skill, it now appears that by the time most of the storm ends late Sunday – rainfall totals of 1” to 2” are possible over eastern New Mexico, with 4 to 6” possible in portions of Texas and Oklahoma - with isolated, T-Storm related totals up to 8”. In addition, 1 to 2 feet of snow is POSSIBLE in the TX/OK Panhandle. Stay Tuned…
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Re: November 2015: Thanksgiving Holiday Outlook

Postby srainhoutx » Tue Nov 24, 2015 12:16 pm

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1100 AM EST TUE NOV 24 2015

VALID 12Z FRI NOV 27 2015 - 12Z TUE DEC 01 2015

...OVERVIEW...

THE UPPER PATTERN CONCLUDING THE END OF NOVEMBER AND ENTERING
METEOROLOGICAL WINTER WILL BE QUITE AMPLIFIED FEATURING A CLOSED
LOW OVER THE CENTRAL GREAT BASIN ON FRIDAY MORNING. THE 00Z GFS
500-MB ANOMALIES SUGGESTS THIS FEATURE IS ROUGHLY 2 SIGMAS BELOW
CLIMATOLOGY.
THE GENERAL IDEA IS FOR THE SYSTEM TO REMAIN IN A
QUASI-STATIONARY STATE THROUGH SATURDAY BEFORE SLIDING EASTWARD IN
RESPONSE TO AN UPSTREAM KICKER. MODELS INDICATE A WELL ESTABLISHED
REX BLOCK ACROSS WESTERN NORTH AMERICA GIVEN THE RIDGE BORDERING
TO THE NORTH WITH UNCERTAINTY IN HOW THIS PATTERN TRANSITIONS TO A
MORE PROGRESSIVE SOLUTION. DURING THIS PROCESS...THE REMNANTS OF
WHAT IS CURRENTLY TROPICAL STORM SANDRA WILL BRING DEEP TROPICAL
MOISTURE INTO THE SOUTHERN PLAINS/LOWER MS VALLEY WITH MODELS
SUPPORTING ABOVE 95TH PERCENTILE MOISTURE CONTENT.
EVENTUALLY THE
PARENT UPPER LOW EVOLVES INTO AN OPEN WAVE WHICH DRAGS THE FRONTAL
ZONE EASTWARD INTO EARLY NEXT WEEK. OVERALL...THE PATTERN ACROSS
THE CONUS WILL BE DOMINATED BY THE SOUTHERN STREAM AS THE NORTHERN
BRANCH REMAINS AMPLIFIED BUT GENERALLY CONFINED TO THE HIGHER
LATITUDES.


...GUIDANCE EVALUATION/PREFERENCES...

EVALUATION OF THE CURRENT GUIDANCE SHOWS DECENT AGREEMENT ACROSS
THE LARGER-SCALE BUT UNCERTAINTIES WITH PLACEMENT AND TIMING OF
THE WESTERN U.S. CLOSED LOW. THIS BROAD NEGATIVE HEIGHT ANOMALY
SHOULD REMAIN SLOW-MOVING...POSSIBLY STATIONARY AT TIMES...THROUGH
SATURDAY. MULTI-DAY ENSEMBLE SPAGHETTI PLOTS HAVE SHOWN A GRADUAL
SLOWING IN THE FORECAST TRACK WHICH HAS BEEN SUPPORTED BY MOST
06Z/00Z MODELS. INTERESTINGLY THE 00Z ECMWF/ECMWF ENSEMBLE MEAN
JUMPED EAST WHICH PLACES IT ON THE FAR EASTERN SIDE OF THE SPREAD.
NOT COMPLETELY CONVINCED OF THIS SCENARIO PLAYING OUT GIVEN HOW
SLOW THESE UPPER LOWS FROM THE WESTERN U.S. TRACK EASTWARD. BUT
ALSO DO NOT WANT TO DISMISS THIS SITUATION EITHER. ON THE SLOWEST
SIDE OF THE SPECTRUM WAS THE 00Z UKMET WHICH WILL NOT BE INCLUDED
INTO THE MIX. TENDED TO FOCUS THE WPC PREFERENCE HEAVILY UPON THE
TRACK OF THE CLOSED LOW WHICH IS THE MOST DOMINANT FEATURE ON THE
MAP. REALLY LIKED CONTINUITY FROM NIGHT SHIFT WHICH INCORPORATED
AT LEAST 50 PERCENT OR GREATER OF THE 12Z ECMWF/ECMWF ENSEMBLE
MEAN PACKAGE. THIS SEEMED TO FOLLOW THAT SLOWER IDEA MOST READILY.
HOWEVER...THE 06Z GFS/00Z ECMWF SUITES DID BUDGE
EASTWARD...PARTICULARLY THE LATTER SO THREW IN APPROXIMATELY HALF
OF THESE SOLUTIONS INTO THE MIX AS WELL.



...SENSIBLE WEATHER HIGHLIGHTS...

THE BIGGEST THREAT DURING THE MEDIUM RANGE IS THE HEAVY RAINFALL
POTENTIAL FROM THE SOUTHERN PLAINS AND INTO THE OZARKS. THIS IS
GENERALLY ALONG THE STALLED BOUNDARY POSITIONED SOUTHWEST TO
NORTHEAST ACROSS THE REGION. THE AFOREMENTIONED TROPICAL PLUME OF
MOISTURE SHOULD INTERCEPT THIS BAROCLINIC ZONE SETTING THE STAGES
FOR VERY HEAVY RAINFALL...PARTICULARLY THROUGH SATURDAY NIGHT. THE
06Z GFS FORECASTS A BROAD AREA OF 4 TO 6 INCHES OF RAINFALL FROM
THE RED RIVER NORTHEASTWARD INTO SOUTHEASTERN MO FROM FRIDAY
MORNING THROUGH SUNDAY MORNING. ADDITIONALLY...ON THE BACK EDGE OF
THIS SYSTEM...THE WPC WINTER WEATHER PROBABILITIES INDICATE A
THREAT FOR SNOW ACROSS THE SOUTHERN HIGH PLAINS THROUGH SATURDAY
MORNING.
IN TERMS OF TEMPERATURES...THE LOWER HEIGHTS ACROSS THE
WESTERN TO CENTRAL U.S. WILL SUPPORT READINGS 15 TO 25 DEGREES
BELOW CLIMATOLOGY WITH 5 TO 10 DEGREES ABOVE FARTHER DOWNSTREAM.
THESE ANOMALIES SHOULD REMAIN A FIXTURE THROUGH SATURDAY BEFORE
THESE READINGS DECREASE IN RESPONSE TO THE GRADUALLY RELAXING FLOW.


RUBIN-OSTER

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Re: November 2015: Thanksgiving Holiday Outlook

Postby srainhoutx » Tue Nov 24, 2015 2:49 pm

Afternoon briefing from Jeff:

A strong storm system will approach TX late this week.

Widespread and prolonged rainfall event to commence on Thanksgiving and last through the weekend.

A large upper level trough will dig into the southern Rockies late this week while at the same time Tropical Storm Sandra in the eastern Pacific intensifies into a category 2 hurricane and eventually becomes captured by the deep layer trough over the SW US by this weekend. Significant amounts of mid and high level moisture will become entrained into the trough and brought NE across TX Friday-Sunday.

Cold surface high pressure responsible for the light freeze over portions of SE TX yesterday morning is now moving eastward allowing surface winds to turn to the SE across the region. This has resulted in a steady increase in low level moisture overnight and this morning and early afternoon satellite images confirm a low level cloud deck advancing into SE TX from the SW. This moist SE low level flow will remain in place the rest of the week and serve to gradually bring dewpoints into the 60’s resulting in muggy humid conditions by Thanksgiving Day. While moisture increases at the surface overall air mass is capped due to dry air above the 850mb level, so do not expect much rainfall activity until Thanksgiving when moisture really begins to deepen.

Upper level trough over the SW US will begin to edge eastward late this week allowing a cold Canadian (modified arctic) air mass to move down the plains and into TX. Models are not handling the overall frontal position very well with the GFS keeping SE TX on the warm and humid side through the weekend while the CMC and ECMWF bring the front into the region and stall the boundary. Expect a fairly significant temperature gradient along the boundary with 70’s ahead of the front and 40’s/50’s behind the front. While the upper level flow is out of the SW this weekend which would normally support a stalling front to our N and W, the air mass is cold and dense and such air masses tend to move more southward then models think under their own density. Think the front will make it into SE TX at some point late Friday, but not confident on how far south it moves….big potential for significant changes in temperatures over the weekend depending on frontal position.

Expect scattered showers to begin to develop on Thursday and increase in coverage and intensity on Friday as the frontal boundary nears. Moisture levels surge to near record levels (yet again) for late November as both moisture from the Gulf of Mexico and TC Sandra is brought over the region. Both surface front and 850mb front will help to focus a prolonged and at times heavy rainfall event. Current WPC rainfall forecasts keep the heaviest rainfall focused over NC TX into SE OK where a solid 5+ inches of rainfall can be expected with isolated amounts upwards of 6-9 inches. Over SE TX these amounts drop quickly toward the coast with the best rainfall chances Friday NW of a line from Columbus to Huntsville. This rainfall forecast is likely only as good as the frontal position as a further southward position of the front would likely shift the axis of widespread training rainfall southward. Additionally, the track of the remains of Sandra across MX and in to TX by early Sunday will certainly have a play in the rainfall potential also.

For now will go with widespread rainfall of 2-3 inches over SE TX Friday-Sunday with isolated amounts of 4-5 inches possible and most likely NW of US 59. Changes to this and the temperature forecast are almost certain in the coming days.

Hydro:
Expected upstream rainfall amounts of N TX late this week and this weekend on top of saturated grounds and high lake levels are concerning. Run-off continues to be passed down area rivers from the recent rainfall events and lakes are running near or over 100% capacity. Additional significant rainfall this weekend will result in large scale run-off and likely lead to gate operations at area flood control reservoirs. Significant rises on area rivers will be likely for the first week on December.
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Re: November 2015: Thanksgiving Holiday Outlook

Postby srainhoutx » Tue Nov 24, 2015 10:15 pm

Sandra becomes a Hurricane...


HURRICANE SANDRA DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL EP222015
800 PM MST TUE NOV 24 2015

Satellite imagery indicates that Sandra has continued to strengthen
during the past several hours. The deep convection now wraps
around the center, and there have been occasional attempts at eye
formation. The initial intensity is increased to 65 kt based on a
satellite intensity estimate from TAFB, a 65 kt estimate from the
CIMSS ADT, and an earlier CIMSS AMSU estimate of 60 kt.

The initial motion is 290/10. The hurricane is currently being
steered by a mid-level ridge extending from southern Mexico
westward over the Pacific. However, a strong deep-layer trough
moving southeastward over the western United States should erode the
ridge north of Sandra during the next couple of days. This
evolution should cause the cyclone to turn northward in about 48
hours and recurve northeastward into the westerlies thereafter.
There has been little change in the track guidance since the last
advisory. Thus, the new track forecast is similar to the previous
forecast in calling for Sandra to pass near the southern end of the
Baja California Peninsula in about 72 hours, followed by landfall in
northwestern Mexico between 72-96 hours. The new forecast lies near
the center of the track guidance envelope.

Sandra has rapidly intensified during the past 24 hours, and this
trend is likely to continue as the hurricane remains in a light
vertical shear environment and over warm sea surface temperatures.
The Rapid Intensification Index of the SHIPS model shows better than
a 60 percent chance of a 40 kt increase in strength during the next
24 hours and an almost 80 percent chance of a 25 kt increase. Based
on this, the intensity forecast has been adjusted upward to show
Sandra becoming a major hurricane in 36 hours, and this part of the
forecast could be conservative. After 36 hours, the cyclone is
expected to encounter strong southwesterly vertical shear, and all
of the guidance forecasts rapid weakening before landfall over
mainland Mexico. After landfall, Sandra should dissipate quickly
over the mountains of northwestern Mexico. Overall, the new
intensity forecast lies near the upper edge of the guidance envelope
and is in best overall agreement with the Florida State
Superensemble.

It is too soon to know exactly how Sandra will affect portions of
the southern Baja California peninsula or the west coast of
mainland Mexico. However, a watch may be required on Wednesday,
and interests in those areas should monitor the progress of Sandra.


FORECAST POSITIONS AND MAX WINDS

INIT 25/0300Z 12.0N 107.9W 65 KT 75 MPH
12H 25/1200Z 12.6N 109.3W 75 KT 85 MPH
24H 26/0000Z 14.0N 110.4W 90 KT 105 MPH
36H 26/1200Z 15.8N 110.9W 100 KT 115 MPH
48H 27/0000Z 17.7N 111.1W 90 KT 105 MPH
72H 28/0000Z 22.0N 109.0W 60 KT 70 MPH
96H 29/0000Z 26.0N 106.0W 20 KT 25 MPH...INLAND
120H 30/0000Z...DISSIPATED

$$
Forecaster Beven



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Re: November 2015: Thanksgiving Holiday Outlook

Postby Katdaddy » Wed Nov 25, 2015 9:06 am

Warm temps with partly to mostly cloudy skies across SE TX this morning. Expect warm, humid, cloudy, weather with scattered showers through Friday afternoon before slightly cooler temps arrive with continued rain chances. Temps approach 80F for Thanksgiving and Friday. Severe weather and flash flooding still not a threat for SE TX. Central and NTX are most likely to see a prolonged rain event which may create flooding conditions by the weekend as moisture from Hurricane Sandra move across TX and combines with a slow moving cold front. Freezing rain will be a concern from NW TX and the TX Panhandle through the weekend. Flash Flood Watches have also been issued across a large portion of OK. If you have travel plans for the holiday weekend, stay weather aware.
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Re: November 2015: Thanksgiving Holiday Outlook

Postby srainhoutx » Wed Nov 25, 2015 10:25 am

The 12Z NAM suggests the cold front hangs up across Metro Houston. Folks to the E in Beaumont and Southern Louisiana may not see much of anything with this storm system.
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Re: November 2015: Thanksgiving Holiday Outlook

Postby srainhoutx » Wed Nov 25, 2015 10:46 am

HURRICANE SANDRA DISCUSSION NUMBER 8
NWS NATIONAL HURRICANE CENTER MIAMI FL EP222015
800 AM MST WED NOV 25 2015

Sandra's convective pattern continues to become better organized,
and a pinhole eye was observed in a 1201 UTC SSMIS microwave pass.
An eye has also been apparent in the latest infrared satellite
images. The intensity is increased to 85 kt based on Dvorak
estimates of T5.0/90 kt from TAFB and T4.8/85 kt from the UW-CIMSS
ADT. This intensity makes Sandra the strongest hurricane in the
eastern North Pacific Ocean for this late in the year (the previous
record was Hurricane Winnie of 1983, which reached an intensity of
80 kt on December 6).


Low shear and warm sea surface temperatures should allow additional
strengthening, and the SHIPS Rapid Intensification Index is still
showing a 3 in 4 chance of a 30-kt increase during the next 24
hours. Therefore, the NHC official forecast continues to show
Sandra reaching major hurricane strength during the next 12-24
hours, in best agreement with the SHIPS and LGEM models.
Southwesterly shear is expected to increase to about 30 kt by 48
hours, and even higher thereafter, which should induce a fast
weakening trend as Sandra approaches the Baja California peninsula
and west coast of Mexico. The official intensity forecast after 24
hours is generally an update of the previous forecast and very close
to the IVCN intensity consensus.

The hurricane appeared to take a short-term jog to the west during
the past 6-12 hours, but the longer-term average motion is still
295/9 kt. A subtropical ridge continues to extend from southern
Mexico westward to near 20N110W, but the ridge is expected to be
shunted eastward during the next 24 hours by an amplifying mid- to
upper-level trough near the west coast of North America. This
should cause Sandra to turn northwestward and northward during the
next 36 hours and then northeastward by 96 hours. The track
guidance is tightly clustered for the first 36 hours, but the
spread increases after that time. The models which maintain a
deeper circulation (i.e., the GFS and HWRF) show a sharper and
faster recurvature, while the models which depict a weakening,
shallower system (i.e., the ECMWF and UKMET) show a slower and more
gradual recurvature. Since fast weakening is expected after 48
hours, the updated NHC track forecast is slowed down and shifted a
bit westward during that period to be closer to the models that show
a faster weakening trend.

Although Sandra is forecast to weaken, it is too soon to know
exactly how Sandra will affect portions of the southern Baja
California peninsula or the west coast of mainland Mexico. A watch
may be required later today or tonight for portions of Mexico, and
interests in those areas should monitor the progress of Sandra.

FORECAST POSITIONS AND MAX WINDS

INIT 25/1500Z 12.6N 109.5W 85 KT 100 MPH
12H 26/0000Z 13.5N 110.3W 95 KT 110 MPH
24H 26/1200Z 15.1N 110.9W 105 KT 120 MPH
36H 27/0000Z 16.9N 111.1W 95 KT 110 MPH
48H 27/1200Z 18.7N 110.9W 80 KT 90 MPH
72H 28/1200Z 22.5N 109.7W 40 KT 45 MPH
96H 29/1200Z 26.0N 106.5W 20 KT 25 MPH...POST-TROP/INLAND
120H 30/1200Z...DISSIPATED

$$
Forecaster Berg
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Re: November 2015: Thanksgiving Holiday Outlook

Postby texoz » Wed Nov 25, 2015 8:35 pm

The Pacific hurricane/typhoon season has been quite impressive. With record warm ocean waters across the globe, including the Atlantic, one wonders what the future will bring.
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Re: November 2015: Thanksgiving Holiday Outlook

Postby unome » Wed Nov 25, 2015 8:57 pm

you have to like NWS Dallas/Fort Worth for their "tell it like it is" forecasting

http://www.srh.noaa.gov/fwd/

Image
Image

safe travels to anyone venturing out this holiday & Happy Thanksgiving y'all !
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