May 2017: Memorial Day/End Of May Outlook

General Weather Discussions and Analysis

Re: May 2017: Western US Low/EPAC Tropical Troubles

Postby MontgomeryCoWx » Wed May 10, 2017 8:51 pm

I did upper 40s and rain for the Kentucky Oaks and Derby last weekend. It was refreshing!
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Re: May 2017: Western US Low/EPAC Tropical Troubles

Postby Katdaddy » Thu May 11, 2017 5:37 am

A few strong storms possible this afternoon mainly N and W of Houston metro where the SPC has a marginal risk area. Our next front will be moving across TX today and approach SE TX tonight. This front will move off the coast Friday morning bringing clearing skies and lower humidity however temps will remain warm through the weekend. TS Adrian has been downgraded to a TD and expected to dissipate later today.
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Re: May 2017: Western US Low/EPAC Tropical Troubles

Postby srainhoutx » Thu May 11, 2017 8:58 am

Thursday morning briefing from Jeff:

Omega block upper air pattern that has been in place for the last week is breaking down allowing a slow moving storm system over the SW US to eject across the plains today into Friday.

Low level moisture has returned to the region below a capping inversion while high level moisture spills across the state from the Pacific on the southeast flank of the upper air storm system over portions of NM and W TX this morning. A surface cool front will progress through TX today and off the coast sometime on Friday. Air mass will likely remain capped today with isolated showers and possibly a thunderstorms late this afternoon with enough surface heating. Overall rain chances look fairly low with the front (20-30%) tonight into early Friday as the main forcing for lift is aimed that the central plains with little to break the cap over our region.

Much drier air mass will filter into the area late Friday with weekend dewpoints falling into the 50’s which will result in overnight lows down into the lower 60’s by Saturday and Sunday mornings. High temperatures will still make the mid 80’s given the rapid heating of the dry air mass and clear skies.

Next Week:
Another upper level storm system drops into the SW US by early next week and once again moisture will begin to return off the western Gulf of Mexico. Will keep rain chances out Monday and maybe Tuesday then begin to raise chances on Wednesday. GFS and ECMWF are not in much agreement on how the upper air pattern will play out next week and just how much rainfall is possible over the region. ECMWF wants to develop a coastal trough and focus heavy rainfall along the coast and possibly into SE TX toward the end of next week while the GFS is mostly dry. Both of these completely opposite solutions appear possible at this time. One other item to keep an eye on is the pool of moisture associated now tropical depression Adrian south of Mexico. If this moisture pool remains in that area as expected for the next several days it could become entrained within the return flow early next week.
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Re: May 2017: Western US Low/EPAC Tropical Troubles

Postby srainhoutx » Thu May 11, 2017 3:13 pm

Thursday afternoon update from Jeff:


SPC has issued a Severe Thunderstorm Watch until 1000pm for the northern counties of SE TX: Trinity, Walker, Madison, Houston, Grimes, Brazos, and Burleson.

Thunderstorms are slowly increasing in region of increasing instability south of a slow moving cold front over NC TX. Air mass has become unstable and capping appears to be eroding which may result in the formation of strong to severe thunderstorms over the next few hours. Main threat will be large damaging hail and strong winds although an isolated tornado cannot be ruled out. Storms may grow upscale this evening into a line and track ESE/E into portions of E TX and the northern portions of SE TX with an increasing wind damage threat.


Severe Thunderstorm Watch Outline and Radar Overlay:
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Re: May 2017: Western US Low/EPAC Tropical Troubles

Postby jasons » Thu May 11, 2017 10:32 pm

I'm glad I watered.
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Re: May 2017: Western US Low/EPAC Tropical Troubles

Postby Cromagnum » Thu May 11, 2017 11:14 pm

jasons wrote:I'm glad I watered.


Yep, this persistent cap is bullshit already. Hardly any rain in April or May so that June-September can scorch the rest.
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Re: May 2017: Western US Low/EPAC Tropical Troubles

Postby Katdaddy » Fri May 12, 2017 5:48 am

Beautiful SE TX weather arrives this morning behind the front this morning and will remain through the weekend. Strong storms pushing into the coastal waters SE and E of Galveston currently. 19 days until the 2017 hurricane season. Day 6 of hurricane preparedness this week is important. Teamwork is very important before, during, and after a hurricane.

Day 6 of 2017 Hurricane Preparedness Week: Check On Your Neighbor

Many rely on their neighbors after a disaster, but there are also many ways you can help your neighbors before a hurricane approaches. Learn about all the different actions you and your neighbors can take to prepare and recover from the hazards associated with hurricanes. Start the conversation now with these Neighbor Helping Neighbor strategies.
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Re: May 2017: Beautiful Mother's Day Weekend

Postby Cromagnum » Sat May 13, 2017 5:20 pm

We almost need some tropical mischief just to have a chance at rain.
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Re: May 2017: Beautiful Mother's Day Weekend

Postby DoctorMu » Sat May 13, 2017 8:15 pm

Cromagnum wrote:We almost need some tropical mischief just to have a chance at rain.


Not much relief on the long term GFS through the end of the month. We have some deep moisture on Wednesday elevating our chances of rain (50% in CLL).


The persistent cap may partly reflect the 10 year drought and CC. Still, the last couple of years tropical mischief has provided a few May and June deluges. We need as much natural water as possible in the ground before July. Far too much Na+ in our sprinkler water, making it alkaline.



.PREV DISCUSSION... /ISSUED 257 PM CDT Sat May 13 2017/

SHORT TERM...
Today`s surface analysis at 19Z was fairly simple with broad weak
high pressure over much of the Plains into Texas. Over SE Texas
light north winds have allowed for some mixing and dewpoints in
the upper 50s to low 60s. Upper level analysis has ridging aloft
over much of Texas and the Plains for that matter. Overall weather
conditions are so quiet that I literally heard a pin drop in the
office. Plus the airmass is pretty stagnant and we are having
ozone action days.

Upper level ridge looks to hold over much of the area through
Monday night. Southerly return flow sets up tomorrow and look for
moisture return to continue for much of the week. Overall this
allows for temperatures to be near or 3 to 5 degrees above normal.

Overpeck

LONG TERM...
The upper level ridge should break down Tuesday into Wednesday
and shift over Florida and SE U.S. A short wave trough should move
out of the southern Rockies into the Plains late Tuesday. This is
also when the subtropical jet becomes more active over the
southern half of Texas. Forecast will keep ongoing rain chances
mainly for Wednesday. GFS shows a good surge of moisture with
precipitable water values 1.5 to 1.9 inches. Overall the pattern
supports decent rain chances mainly north of Houston for the
middle of the week. The stronger upper level ascent looks to
remain even farther north over the Plains Tuesday night and then
another upper level low deepens over the Rockies going into
Thursday. Look for rain chances of 20 to 30 percent to continue
for the end of next week. Best chances look to be Wednesday with
the initial surge of moisture. There may be a threat for heavy
rainfall Wednesday through the end of the week, but models seem to
be keying on Wednesday the most. One thing that seems to be
missing from the atmospheric set up for heavy rain is a stalled
frontal boundary. Quite possible that outflow from previous
convection could provide this on the mesoscale but still plenty of
time to figure out these details. For now the heavy rainfall
potential for Wednesday remains just a potential and something to
monitor.
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Re: May 2017: Quiet WX Pattern Continues For Now

Postby srainhoutx » Mon May 15, 2017 9:28 am

Monday morning briefing from Jeff:

After several weeks of generally nice weather…the upper air pattern will undergo changes that will allow a return of thunderstorms across the southern plains this week into next week.

Upper level blocking with high pressure over the southern plains the last week is shifting eastward allowing the semi-stationary upper level trough over the SW US to edge closer to the southern plains. The initial trough will eject into the plains on Wednesday, but a secondary trough will quickly dig back into the SW US late this week and very slowly move into the plains this weekend into early next week. Locally onshore winds have already returned to the region allowing a slow but steady increase in Gulf moisture. Air mass will slowly moisten over the next 48 hours before a surge of deeper moisture arrives on Wednesday. Will raise rain chances to 40% for Wednesday as this deeper moisture arrives and SE TX may get skirted by the tail end of lift from the ejecting SW US trough. Main dynamics with this system are aimed more toward the central plains. This week will provide near daily chances of severe weather including tornadoes across the plains.

Secondary trough digs into the SW US Thursday and Friday and this will position a SW flow aloft across the region. Weak disturbances in this flow aloft combined with the W TX dryline may result in complexes of thunderstorms developing to our west each afternoon and moving eastward during the overnight hours. Big questions at this time range are do any of these complexes make it as far east as SE TX or do their outflow arrive into the region during peak heating. Given a moist and generally unstable air mass in place from Wednesday onward will have to keep an eye on such potential.

Sub-tropical ridge aloft will shift a bit eastward this weekend and this will allow a very slow motion of the SW US trough eastward. A surface cold front will move into the state from the NW helping to act as a trigger for deep convection. Upper air parameters may become more favorable also for thunderstorm formation along with continued ejecting short wave disturbances out of the mean trough to our west. Timing of this all remains in question, but models are starting to key in on Saturday as the first day for potential widespread thunderstorms. Also starting to see a heavy rainfall signal in the models with QPF maxes of 3-5 inches over the weekend likely from some sort of slow moving thunderstorm complex (something to watch very closely).

Very slow movement of the upper trough will continue to favor rounds of thunderstorms into early next week allowing rainfall totals to pile up. Each rough will likely pose some risk of severe weather given it is mid May and instability is generally decent this time of year. QPF amounts are highest across central TX into OK this week and enough rain may fall, even though grounds are generally dry, to activate run-off and rises on upstream rivers and creeks. Heavy rainfall signal drifts deeper into SE TX this weekend into early next week.
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