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Texas/New Mexico/Louisiana/Mexico Obs And Discussion Thread Part 3

Srain

By Srain,
in Central/Western States

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Quixotic1

Quixotic1

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I was considering posting that same image! I think we will have a couple of opportunities in Dec and early Jan but I am not buying early Dec fun just yet :gun_bandana:

I think we'll get some cold shots when the pattern buckles ( and it will), but the persistence of the dry pattern bothers me. Every precip event seems to fizzle.

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Srain

Srain

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Morning e-mail from Jeff:

After a cold morning across the area, much warmer conditions will be place this weekend into the middle of next week along with additional chances for rainfall.

Cold surface high NE of the region this morning did not produce calm winds overnight as winds have already swung around to the E/SE at 5-10mph and so temperatures have only fallen into the upper 30’s and low 40’s. As this high moves east today, winds will turn to the SE and the return of moisture will be underway. Expect a deck of clouds to develop and begin to push inland later today with skies going mostly cloudy this evening. Humidity will increase overnight along with lower level clouds and by late Saturday a few showers may even develop especially west of I-45. Slightly better chances of rainfall look possible on Sunday as a weak short wave crosses the area along with warm air advection and increasing Gulf moisture. Air mass actually starts to become unstable Sunday afternoon with LI’s of -2 to -4 and trigger temperatures in the low 80’s so incoming streamer showers off the Gulf Saturday night may be able to grow into heavier convective showers or even a thunderstorm or two on Sunday. For now will throw in 30% across the entire area for Sunday, but these chances may need to be raised on Saturday.

Long wave trough developing over the western US late this weekend will help expand the downstream sub-tropical ridge over the Gulf of Mexico into TX Monday (especially the coastal sections) helping to lower rains chances although warm and humid conditions will prevail. Trough and its associated cold front will move eastward into TX starting late Monday and slowly move across the state. Moisture values increase to very high levels (PWS 1.8-2.0 inches) next Tuesday pointing strongly toward an excessive rainfall potential over the upper TX coastal plain and parts of SE TX where a slow moving frontal boundary will be found. These moisture values are nearly 200% of mid-late November standards and with a slow moving boundary in place training excessive rainfall will be possible. Severe threat looks more marginal with this system than the last system, so only a few isolated severe reports are expected.

Storm system should clear SE TX by Wednesday with improving conditions for the holiday part of next week into next weekend. Temperatures should be seasonal (40’s to 70’s) under mostly clear skies.

Note: Record breaking cold air has built into Alaska this week with lows of -40 to -50 below zero in much of the interior part of the state. To this point there has been no favorable upper air delivery pattern of this air southward into the US, but long range models have been and continue to hint at the potential for a significant cold air intrusion into the US just beyond the Thanksgiving time period. When that time arrives, will have to see if this bitter cold air mass is still lurking over Alaska.

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Srain

Srain

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The cold front has sagged S this morning just N of College Station. The front should retreat N a bit setting the stage for severe weather for our neighbors to the N and a bit W. Our area will remain capped today and temps will approach the record of 85F as moisture continues to surge off the Gulf. Any cloud cover today may keep that record safe today as we saw yesterday, but these higher temps will be short lived as the front moves back S tomorrow. The SPC still has a Slight Risk just N and W of our area for today and tonight. We should see that Risk Area move S and E with strong down bursts and hail being the primary threat for tomorrow. An isolated tornado or two cannot be ruled out E of I-45 for tomorrow. QPF forecasts still suggest above an inch for areas mainly N of I-10 for tomorrow. Thanksgiving looks nice with temps in the upper 60's to low 70's. The upcoming weekend will be the time to monitor as a very strong storm complex moves in from the W.

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Srain

Srain

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Morning e-mail from Jeff:

Very active weather pattern expected this week with multiple impacts into the holiday weekend

Strong cold front sitting across TX this morning with temperatures in the 40’s and 50’s north of the boundary and muggy 70’s south of the boundary. Current temperature is 73 at Austin and 48 at Temple (or even better 59 at Austin Exec and 73 at Austin Bergstm). Front has been bleeding very slowly southward overnight and is just north of College Station due mainly to air mass density behind the boundary…cold air is heavier than warm air! Front should come up stationary shortly as incoming short wave over New Mexico ejects NE across the boundary…in fact the eastern part of the front over east TX may drift northward this afternoon under strong warm air advection. Widespread wetting rains will fall across much of NC and N TX tonight as copious moisture is forced up and over this front. Over SE TX, the ole’ capping inversion remains in place and although moisture has greatly increased over the weekend (PWS of 1.5 inches and dewpoints in the low 70’s) thunderstorms will not be able to form with the warm mid layer. Will see a few streamer showers move inland off the Gulf today and tonight and a few locations could pick up a quick .25 of an inch mainly west of I-45. Highs today will be near record levels at most of the major climate sites.

Another item this morning is the threat for nearshore sea fog today as dewpoints in the lower 70’s ride over nearshore waters in the upper 60’s. So far visibilities have averaged 2-4 miles over Galveston Bay, but quickly lower eastward today the TX/LA line and into LA. Do not think the dewpoint spread over the water temperature is great enough for widespread dense sea fog, but a few patches especially over Galveston and Chambers counties is possible.

Cold front north of the area will begin its SE push on Tuesday as the short wave departs to the NE. Combination of deep moisture, frontal forcing, and splitting jet aloft will create a pattern favorable for lines or clusters of thunderstorms. Models slowly move the front across the area on Tuesday with showers streaming inland off the Gulf ahead of the boundary and a line of thunderstorms along the boundary. While the air mass will be unstable, parameters look week for severe thunderstorms, with may be a few marginal wind gusts toward severe levels. Even non-severe winds have been causing some problems of late with the widespread tree mortality from the ongoing drought across the region.

Other issue is rainfall amounts. Models are showing a widespread .5-1.0 inch across the region and this seems very much reasonable given the parameters in place. I am somewhat concerned with the deep moisture in place and the expectation of a slow moving boundary as this is the set up for training excessive rainfall. Additionally water vapor shows moisture starting to peel off from TS Kenneth in the EPAC and this high level flow will likely get entrained across the area. PWS of 1.6-1.8 inches for mid-late November does raise a few red flags as this is pushing the +2 SD for this time of year. If cell training develops, some areas could see much higher rainfall amounts over 2-4 inches in a short period of time. Will favor the area east of I-45 for the best potential of any training. Dry grounds should help mitigate any flash flood threat, but the situation warrants close watch on Tuesday as with these kind of moisture levels you can quickly get into problems.

Storm system will be east of the area Tuesday night with clearing skies and nice weather expected Wed-Thurs. The area should be able to squeeze out a decent Thanksgiving with lows in the 40’s and highs in the low 70’s under mostly sunny skies.

Progressive flow will speed up more come late week with the next storm system rapidly approaching the area Friday/Saturday or about 3 days faster than the week-week system since the end of October. Will see a very quick return of moisture Thursday night with skies going cloudy by early evening Thanksgiving. Air mass will become unstable enough by midday Friday for showers and thunderstorms to break out in a strong warm air advection regime. Fast moving storm system will cross the area Friday night with a cold front sweeping off the coast early Saturday. Will follow the faster GFS solution for this event with a squall line likely developing just west of the area Friday night and moving across the region early Saturday morning. Could see some severe weather with this system, but much depends on how quickly moisture is able to return and the quality of that moisture. EPAC tap from Kenneth would likely support additional heavy rainfall, but current fast motion of this system will limit rainfall production to a short time window from midday Friday to early Saturday morning.

Clearing and colder for the holiday weekend.

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Srain

Srain

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Brownsville beginning to chatter about the end of the long Thanksgiving Holiday Weekend...what's that I see...frost potential in the RGV...

MORE CONFIDENCE EXISTS FOR THE REMAINDER OF THE WEEKEND INTO NEXT

MONDAY. AFTER A GOOFY ECMWF SOLUTION EARLIER THIS MORNING...WHICH

TOOK DEEPENING TROUGH MOVING THROUGH THE SOUTHWEST U.S. AND CUT IT

OFF OVER BAJA CALIFORNIA...ALL MODELS ARE IN DECENT AGREEMENT WITH

A HIGHLY MERIDIONAL TROUGH WHICH WILL BRING WINDY...VERY DRY...AND

COOLER TEMPERATURES ESPECIALLY BY SUNDAY. GFS/ECMWF EACH SHOW 45+

NORTH NORTHWEST FLOW JUST OFF THE DECK FROM SATURDAY AFTERNOON

INTO SUNDAY MORNING...WHICH COULD BRING 30 TO 40 MPH AND GUSTY

FULLY MIXED WINDS TO ALL OF DEEP SOUTH TEXAS/RGV SATURDAY

AFTERNOON FOLLOWED BY A SOMEWHAT BLUSTERY DAY ON SUNDAY. THE WINDS

MAY MAKE FOR SOME TRAVEL DIFFICULT ACROSS ALL OF SOUTH

TEXAS...PARTICULARLY ON SATURDAY AFTERNOON. HAVE GONE CLOSE TO THE

MILD GFS SATURDAY AS THE COLD AIR SURGE HOLDS OFF UNTIL LATE

AFTERNOON. SUNDAY COULD SEE TEMPERATURES FAIL TO REACH 70 DESPITE

FULL SUNSHINE...A TRUE SIGN THAT DECEMBER IS NEAR.

THE COLDEST NIGHT OF THE YEAR WILL FOLLOW MONDAY MORNING...AND

WOULD NOT BE SURPRISED TO SEE PREFERRED POCKETS SUCH AS

ZAPATA/MEDINA AIRPORT EDGE TOWARD THE FREEZING POINT. A BEAUTIFUL

AFTERNOON WITH MODERATING TEMPERATURES...STILL A LITTLE BELOW

AVERAGE...WILL BEGIN THE FIRST WORK WEEK AFTER THE HOLIDAY.

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Ed Lizard

Ed Lizard

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Another reason to hate cold weather that isn't nice enough to at least snow.

You know all those Spring days where the cap never breaks because deep Gulf air with 70ºF dewpoints moving over 65º shelf waters cause low clouds that don't allow significant heating? Think of the Spring thunderstorm season and hope for less cold than usual shelf waters, people.

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Srain

Srain

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Morning e-mail from Jeff:

Cold front crossing SE TX this morning with ongoing showers and thunderstorms across the region.

At 600am a cold front extended from near Tyler to College Station to San Antonio moving ESE at 15-20mph. Numerous thunderstorms have developed along the boundary from Lufkin to Brenham. A secondary band of thunderstorms is rapidly developing over Wharton and Matagorda Counties and this band will be moving toward Fort Bend and Harris Counties shortly. While the air mass is unstable, frontal timing (early morning) and weak shear will support on a very marginal severe weather threat for the morning hours as the front crosses the area. Most severe modes will be isolated wind damage and this threat will be mainly north of I-10.

Faster frontal movement and rapid forward cell motion is helping to mitigate the heavy rainfall in this highly tropical air mass over the region. Could see a period of cell training along and just N of the US 59 corridor this morning for a few hours as radar shows this is where cells are developing ahead of the main line, but incoming front will shift this activity E/S in a few hours. Rainfall amounts will average .5-1.0 inch with a few isolated totals up to 1.5 inches especially north of I-10 and east of I-45. Front should be reaching the coast early this afternoon or several hours faster than what models were showing yesterday. Rain will end quickly from NW to SE post front with clearing skies by late afternoon.

Dry weather on tap for Wednesday and Thursday with weak high pressure in control before rapid changes Friday-Sunday. Lows in the 40’s and 50’s and highs in the 70’s both days under mostly sunny skies.

Next very strong storm system will begin to approach the area Friday with a rapid influx of moisture starting very late Thursday night. Deep moisture with PWS progged to rise again toward 1.8 inches by Friday afternoon will support the formation of showers and thunderstorms. Strong deep layer lift from the trough moves into the area late Friday night into Saturday with widespread thunderstorms expected. System does support some severe potential along with heavy rainfall, but as with the last several looks fast moving.

Strong high pressure will build southward behind this system with low pressure deepening over the lower MS valley Saturday and Sunday. Impressive pressure rising over TX will support very strong post frontal winds Saturday into Sunday with sustained speeds of 20-30mph and gust over 35-40mph. This system will also tap some cold air over the northern US and expect falling temperatures on Saturday under strong cold air advection regime (highs in the 70’s early falling into the 50’s during the afternoon). Cold high pressure will settle over the region Sunday evening with freezing temperatures possible in some areas Monday morning. Another strong front with modified arctic air appears possible just beyond this weekend (early next week) with even colder conditions and the threat of a more widespread freeze.

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Srain

Srain

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There is still some timing issues regarding the Thanksgiving Weekend storm system, but the models are suggesting a squall line over night Friday into Saturday. The trends continue to suggest a strong front with modified Canadian air being pulled S into the Plains as the Upper Low closes off somewhere in the mid Mississippi River Valley. It does look like we will see very breezy conditions behind the front and Sunday night could bring freezing conditions to at least the I-10 corridor. We will see.

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wxmx

wxmx

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Canadian is an outlier, but would be even more unpleasantly cold late weekend/early week.

I think the CMC is too cold for the 2nd shot, my guess is that it will be a run of the mill cooling with departures of -3 to -6F on average. Even the first shot looks a bit too cold, especially IMBY, implying snow in the mountains around...no way that's going to happen.

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Srain

Srain

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The guidance continues to struggle beyond 48 hours. The NAM and Euro have slowed the front down a bit for Saturday. While showers and storms still look likely Saturday morning into mid day, the rain amounts seem to not be as much as earlier indicated. The big news is what happens after the front/trough passes. The Euro has switched back to a cut off solution with a mid/upper low just to our E. The northern stream across the Great Lake/Upper Mid West is very progressive, so we may see this cut off solution in the southern flow play out. The disturbance is still offshore of California this morning so there will likely been further changes in the wacky guidance in this pattern. It still looks very breezy and cold behind the front for Saturday night into Sunday. If the cut off low that the Euro suggests happens, those cold and breezy conditions could extend into Monday. We will see...

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