August 2015 - Isolated Rain Chances to End August

[wxman57]

Uh-oh.
http://old.ecmwf.int/products/forecasts ... !chart.gif

I'm not sure why you say "Uh-oh", Paul. The European model is agreeing with the GFS that the trof along the East U.S. Coast will back west into the Gulf and develop that upper low along the Mid Gulf Coast. The only differences I see is that the Euro brings the upper low into Texas a little earlier than the GFS. Both are indicating the pattern change starting next weekend, though.

[ticka1]

will the pattern change indicate better changes for rain and temps in the 90's?

[wxman57]

will the pattern change indicate better changes for rain and temps in the 90's?

Definitely. Low pressure overhead = moisture, clouds, and rain. High pressure overhead = current heat wave and this coming week.

[srainhoutx]

The operational and ensemble guidance are in good agreement suggesting an Westward moving upper low/shear axis will develop across the Northern Gulf Coastal States moving toward Texas and finally shift the pesky upper ridge West bringing lower temperatures and increasing shower/storm chances around this time next week. Fingers crossed!

[kennethb]

wxman57 will appreciate this. Here in Baton Rouge I just made my daily bike ride. Temp is about 98, Dewpoint 78 and heat index 115. Can't get much better than this!!! The cold water after the bike ride was the best. Looks "cooler" by next weekend with highs maybe down to lower 90's

[wxman57]

wxman57 will appreciate this. Here in Baton Rouge I just made my daily bike ride. Temp is about 98, Dewpoint 78 and heat index 115. Can't get much better than this!!! The cold water after the bike ride was the best. Looks "cooler" by next weekend with highs maybe down to lower 90's

Sort of a dry heat (RH = 53%).

We biked last evening up through downtown and down Buffalo Bayou to see all the newly-lighted trails at night. Left at 7pm and got home around 10:30pm.

Models remain on track with next weekend's pattern change. Back to more normal temps and a fair chance of rain by next Sunday/Monday.

[Paul Robison]

Uh-oh.
http://old.ecmwf.int/products/forecasts ... !chart.gif

I'm not sure why you say "Uh-oh", Paul. The European model is agreeing with the GFS that the trof along the East U.S. Coast will back west into the Gulf and develop that upper low along the Mid Gulf Coast. The only differences I see is that the Euro brings the upper low into Texas a little earlier than the GFS. Both are indicating the pattern change starting next weekend, though.

"Uh-oh," is because of possibility that that low could develop into a TC. Of course, we do need the rain, regardless.

[wxman57]

There are no indications that this upper-level low (not surface low) is any tropical threat. However, once the ridge moves out of Texas we ARE open to a possible tropical threat down the road.

[Paul Robison]

There are no indications that this upper-level low (not surface low) is any tropical threat. However, once the ridge moves out of Texas we ARE open to a possible tropical threat down the road.

Which model and model run suggests this, Wxman57? The CMC?

[Ptarmigan]

The operational and ensemble guidance are in good agreement suggesting an Westward moving upper low/shear axis will develop across the Northern Gulf Coastal States moving toward Texas and finally shift the pesky upper ridge West bringing lower temperatures and increasing shower/storm chances around this time next week. Fingers crossed!

Let's hope for it.

[Paul Robison]

The operational and ensemble guidance are in good agreement suggesting an Westward moving upper low/shear axis will develop across the Northern Gulf Coastal States moving toward Texas and finally shift the pesky upper ridge West bringing lower temperatures and increasing shower/storm chances around this time next week. Fingers crossed!

Let's hope for it.

I agree with you.
BUT:
Just remember that, in a Houston summer, a storm can briefly pulse to strong/severe levels, so be on guard.
Oh, I forgot to ask: Is this the same upper low that's been causing flooding woes in Florida?

[srainhoutx]

One more day of hot and dry then rain chances begin to increase mainly E of the I-45 Corridor as a weak surface front begins its approach across Arkansas and Louisiana. The short term meso guidance as well as the operational GFS and Euro suggest scattered daytime storms develop tomorrow afternoon into the evening hours as the frontal boundary nears East Texas. It still will be hot, but this marks the beginning of a pattern change that looks to extend into next weekend and possibly early next week. The pesky upper ridge begins to nudge West as a deepening trough develops across the Eastern United States and pressures begin to lower across the Northern Gulf Coast late week into next weekend. The medium and longer range guidance suggests this sort of pattern with lower pressures across the Gulf of Mexico may continue into the end of August with Texas and Louisiana returning to a somewhat unsettled pattern and daily chances of scattered showers and thunderstorms. Fingers crossed. We may be nearing the end of the pesky pattern that arrived July 1st and has been relentless.

[srainhoutx]

Morning briefing from Jeff:

Heat Advisory remains in effect until 800pm this evening

Area continues to bake under strong upper level ridging, yesterday evening soundings are starting to show small changes in the upper pattern which will finally lead to a break in this heat wave. This will not happen before some of the hottest temperatures of 2015 are felt today and Tuesday. IAH has recorded 4 straight days at or above 100 including 102 yesterday. We continue to maintain borderline heat advisory criteria each afternoon with heat index values topping out in the 106-110 range…generally highest near the passage of the seabreeze front when dewpoints spike.

Will go with widespread low 100’s this afternoon with most sites hitting 100-103 and a degree or two warmer on Tuesday. Tuesday will feature the approach of a weak cool front and compressional heating ahead of this boundary and SW surface winds will support a rapid and strong warm up. Highs on Tuesday of 102-105 appear likely. Increasing moisture an incoming boundary into a super-heated late day air mass looks to support a chance of strong thunderstorms. Sub-cloud layer will be dry and soundings show an inverted “V” profile favorable for strong and possibly damaging winds. Models have become a little more aggressive with rain chances on Tuesday and may need to up chances to 30% if the trend continues.

Boundary will be across the area on Wednesday and with clouds and a better chance at thunderstorms temperatures will likely be held to the upper 90’s. Not overly confident the front will push off the coast and allow a drier air mass to move SW into the region Thursday and Friday. Should the drier air mass work into the region high temperatures will be back at or above 100 for the end of the week.

More Significant Changes:
A strong upper level trough will move into the eastern US this week and then begin to retrograde (move westward). Models are coming into better agreement on this trough moving westward along the US Gulf coast late this weekend into early next week with the heat ridge breaking down and shifting into the SE US. This would be a favorable moist flow pattern for TX and both the ECMWF and GFS show decent height falls over the region by early next week. This change would certainly allow for cooling afternoon temperatures and possibly a daily shot of seabreeze thunderstorms.

Fire Weather:
Dry air aloft continues to mix to the surface each afternoon prior to the seabreeze. BUSH IAH dewpoint of 69 Saturday afternoon shot up to 77 with the seabreeze passage. Near critical fire weather conditions are expected each afternoon between noon and 400pm prior to the seabreeze passage. Luckily winds have been running less than 15mph. Fine fuels are showing poor conditions with fine fuel moisture running at less than 10%. Pan evaporation rates are on the order of .25 to .35 of an inch daily over the region. Over the past 7 days there have been 24 wild/grass fires over SE TX. KBDI values are running 700-800 over much of Trinity, Polk, San Jacinto, and Liberty Counties indicating no moisture in the soil layer 7-8 inches deep.

67 TX counties are under outdoor burn bans including:
Chambers, Galveston, Matagorda, Wharton, Waller, Grimes, Madison, Walker, San Jacinto, Houston.

[srainhoutx]

The Afternoon Updated Climate Prediction Center Day 8+ Outlook suggests cooler temperatures and certainly more rainfall than we have experienced since the 1st of July.

[Texaspirate11]

I got my rain sticks out.
Enough already.

[Paul Robison]

Morning briefing from Jeff:

Heat Advisory remains in effect until 800pm this evening

Area continues to bake under strong upper level ridging, yesterday evening soundings are starting to show small changes in the upper pattern which will finally lead to a break in this heat wave. This will not happen before some of the hottest temperatures of 2015 are felt today and Tuesday. IAH has recorded 4 straight days at or above 100 including 102 yesterday. We continue to maintain borderline heat advisory criteria each afternoon with heat index values topping out in the 106-110 range…generally highest near the passage of the seabreeze front when dewpoints spike.

Will go with widespread low 100’s this afternoon with most sites hitting 100-103 and a degree or two warmer on Tuesday. Tuesday will feature the approach of a weak cool front and compressional heating ahead of this boundary and SW surface winds will support a rapid and strong warm up. Highs on Tuesday of 102-105 appear likely. Increasing moisture an incoming boundary into a super-heated late day air mass looks to support a chance of strong thunderstorms. Sub-cloud layer will be dry and soundings show an inverted “V” profile favorable for strong and possibly damaging winds. Models have become a little more aggressive with rain chances on Tuesday and may need to up chances to 30% if the trend continues.
Boundary will be across the area on Wednesday and with clouds and a better chance at thunderstorms temperatures will likely be held to the upper 90’s. Not overly confident the front will push off the coast and allow a drier air mass to move SW into the region Thursday and Friday. Should the drier air mass work into the region high temperatures will be back at or above 100 for the end of the week.

More Significant Changes:
A strong upper level trough will move into the eastern US this week and then begin to retrograde (move westward). Models are coming into better agreement on this trough moving westward along the US Gulf coast late this weekend into early next week with the heat ridge breaking down and shifting into the SE US. This would be a favorable moist flow pattern for TX and both the ECMWF and GFS show decent height falls over the region by early next week. This change would certainly allow for cooling afternoon temperatures and possibly a daily shot of seabreeze thunderstorms.

Fire Weather:
Dry air aloft continues to mix to the surface each afternoon prior to the seabreeze. BUSH IAH dewpoint of 69 Saturday afternoon shot up to 77 with the seabreeze passage. Near critical fire weather conditions are expected each afternoon between noon and 400pm prior to the seabreeze passage. Luckily winds have been running less than 15mph. Fine fuels are showing poor conditions with fine fuel moisture running at less than 10%. Pan evaporation rates are on the order of .25 to .35 of an inch daily over the region. Over the past 7 days there have been 24 wild/grass fires over SE TX. KBDI values are running 700-800 over much of Trinity, Polk, San Jacinto, and Liberty Counties indicating no moisture in the soil layer 7-8 inches deep.

67 TX counties are under outdoor burn bans including:
Chambers, Galveston, Matagorda, Wharton, Waller, Grimes, Madison, Walker, San Jacinto, Houston.

NOAA says:
A COLD FRONT WAS SAGGING DOWN INTO OK/AR WITH MUCH COOLER AIR IN
ITS WAKE WHILE THE UPPER RIDGE STILL IS PARKED OVER TX. THIS UPPER
RIDGE SHOULD SLOWLY SLIDE WESTWARD TUESDAY BUT STRENGTHEN AS IT
DOES SO WITH 500 HEIGHTS RISING FROM TODAYS 592 TO 594DM. THIS
CREATES THE QUANDARY OF STRONG SUBSIDENCE BUT A SHALLOW COLD
FRONT SPREADING INTO THE AREA TUESDAY EVENING/WEDNESDAY MORNING.
MOISTURE IS FORECAST TO POOL ALONG THE BOUNDARY AND CONDITIONS
SEEM FAVORABLE FOR AT LEAST ISOLATED THUNDERSTORMS ALONG THE
BOUNDARY AND POSSIBLY GREATER COVERAGE LATE IN THE AFTERNOON
TUESDAY AND NIGHT. FOR NOW WILL CARRY 20-30 POPS LATE TUESDAY
AFTERNOON/NIGHT BUT THESE COULD NEED A NUDGE UP IF THE RIDGE ISN`T
AS STRONG OR COLD FRONT ARRIVES DURING PEAK HEATING...OR DOWN IF
THE RIDGE IS STRONGER OR THE FRONT ARRIVES LATER. IF STORMS DO
FORM IN THE AREAS MAINLY NORTHEAST TUESDAY AFTERNOON THE PROFILE
IS FAIRLY JUICY WITH CAPE OF 1800-3000J/KG WITH SIGNIFICANT DCAPE.
STRONG GUSTY STORMS A POSSIBILITY WITH BRIEF HEAVY DOWNPOURS AND
LIGHTNING. OF COURSE WITH THE LIGHTNING WILL COME A THREAT OF FIRE
STARTS GIVEN THE DRY FUELS AND SHORT TERM DROUGHT THAT IS ONGOING.
THE MOISTURE TOMORROW BEING RICHER WITH THE HEIGHTS ON THE
INCREASE IS INCREASING THE HEAT THREAT AND EXPECT TO SEE MORE
105-112 DEGREE HEAT INDEX READINGS TOMORROW. WILL HOIST ANOTHER
HEAT ADVISORY FOR THE AREA TUESDAY. WE CAN HOPE THAT STORMS START
EARLY AND CURTAIL THE AFTERNOON HIGHS WITH CLOUD COVER BUT THAT IS
PROBABLY JUST HOPE. (probably!)

I'd say points NE of the metro have a better shot at severe weather than we do.

[Katdaddy]

Another very hot day across SE TX with highs in the low 100s and Heat Advisories in effect. Thanks to increased moisture, the combination of the sea/bay breeze, and outflow boundaries from LA; isolated thunderstorms will be possible from late this afternoon and tonight mainly along the coastal areas; as well as, areas NE/E of Houston metro. A few storms could be strong to severe with damaging downburst winds being the main threat. Tomorrow a weak cool front will drift into SE TX and keep slight thunderstorm chances in the forecast as it interacts with sea/bay breeze mainly along the coastal areas. Slight thunderstorm chances will continue until Thursday evening before more mostly sunny skies arrive. A pattern change to slightly cooler highs with increased shower and thunderstorm chances look possible for late in weekend and into next week. The tropics remain quiet across the Atlantic Basin.

[srainhoutx]

Morning briefing from Jeff:

Heat advisory remains in effect until this evening.

Another day or brutal heat across the region ahead of a weak boundary progged to enter SE TX late this afternoon. WSW winds ahead of this feature combined with compressional heating supports highs in the low to mid 100’s this afternoon. Record highs may be tied or broken at IAH today. Moisture levels will also be on the increased ahead of the weak frontal boundary which will help to push afternoon heat index values into the 105-112 degree range. Looks like we will meet heat advisory criteria both on the heat index and actual air temperature this afternoon.

Thunderstorms:
With the upper ridge starting to recede to the NW SE TX has come under the eastern influence of the ridge axis allowing NNE upper level flow, weakening subsidence, and deepening moisture. A surface boundary is dropping southward through northern LA and SE OK this morning with a complex of thunderstorms ongoing over NE LA. Expect outflow boundaries to build SSW this afternoon and enter into our super heated air mass late this afternoon and early this evening. At the same time the seabreeze and baybreeze will move inland and will likely collide with the SSW/SW moving activity out of W LA early this evening. Forecast soundings show a strong inverted “V” profile or dry sub cloud layer over SE TX this afternoon and this supports strong winds from microbursts and downbursts as the drier low level help to evaporate some of the rain in the rain shafts as it falls from the cloud base. Gusty to severe level winds (60mph) may be possible with some of the storms this afternoon.

Boundary is over the area on Wednesday and expect another round of afternoon thunderstorms to develop and move southward over the region once temperatures reach the upper 90’s to low 100’s. Damaging winds will be possible again on Wednesday with soundings still showing an inverted “V” profile.

Fire Weather:
Near critical fire weather conditions over the eastern half of SE TX this afternoon with isolated thunderstorms producing lightning and strong gusty winds. Any fires that might be started by lightning in/near thunderstorms will pose a potentially fast and erratic burn rate due to quickly shifting winds and wind speeds near the convective activity. Fine fuels remain in poor health and readily available to burn. Widespread wetting rains do not appear likely today or Wednesday, so the fire danger will remain elevated.

Extended Outlook:
Model agreement continues to increase with a more pronounced pattern changes this weekend into early next week which should break the heat wave and allow better rain chances. Upper trough along the US east coast late this week begins to retrograde westward into the central Gulf region and then possibly as far west as the NW Gulf late this weekend and early next week. The upper air heat ridge is pushed far to the west of TX allowing lowered heights aloft . Deep tropical moisture also moves toward the TX coast. All this is pointing toward more normal afternoon temperatures in the mid 90’s and at least a daily chance of rainfall.

[Texaspirate11]

HAPPY BIRTHDAY TO DAVID PAUL!
Hope he sees this!

[GBinGrimes]

HAPPY BIRTHDAY TO DAVID PAUL!
Hope he sees this!

Thanks for posting that it's David Paul's birthday. I really enjoy his genuine enthusiasm about weather and especially that he's a home grown meteorologist.

Happy Birthday David!