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

[Srain]

It appears the 12Z GFS is a bit too progressive as compared to the Euro/Ukmet/Canadian. While there are some differences regarding where the U/L will close off in the southern stream via the latter operational guidance, the over all theme of the 12Z suite suggests a chilly Sunday into Monday.

[Ed Lizard]

The GFS and Canadian are quite different. The Canadian looks like the worst cold weather slips East of here.

[Ed Lizard]

HGX discussion doesn't really identify their preferred model, but based on half to an inch of rain tomorrow, it might be the Euro, which is more optimistic than the US models.

[Ed Lizard]

GFS getting a little more sanguine...

[Ed Lizard]

Beyond the res chop, but the GFS kills all the banana plant leaves, and I may have to throw a blankie over my citrus trees.

[Srain]

The 12Z Euro has trended a bit W and also cuts off the upper low over Louisiana which is somewhat similar to the Canadian/Ukmet solution). It appears that the guidance is trending to slow the progression of the trough/Upper Low which would tend to mean breezy and cooler temps extending into Monday. We will see...

[Ed Lizard]

The 12Z Euro has trended a bit W and also cuts off the upper low over Louisiana which is somewhat similar to the Canadian/Ukmet solution). It appears that the guidance is trending to slow the progression of the trough/Upper Low which would tend to mean breezy and cooler temps extending into Monday. We will see...

Check the local area Canadian Global 4 panel maps on the PSU e-Wall. I'm fairly certain this time of the year surface temps won't support anything significant, but extreme East Texas and parts of Louisiana would seem to have favorable thicknesses and moisture to mix in some snow IF the Canadian verified.

[Srain]

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1125 PM CST FRI NOV 25 2011

VALID 261200Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE LOWER MS VALLEY...

...LOWER MS VALLEY...

LATEST SHORT RANGE MODEL GUIDANCE IS A BIT MORE AGGRESSIVE IN THE

PROGRESSION OF PLAINS UPPER TROUGH AS IT DIGS TOWARD THE ARKLATEX

AND FORMS A CLOSED CIRCULATION BY THE END OF THE PERIOD. THIS

EVOLUTION IS SUPPORTED BY STRENGTHENING MID LEVEL FLOW ON THE BACK

SIDE OF TROUGH OVER THE CNTRL ROCKIES WHICH SHOULD DRIVE SEWD INTO

TX LATE IN THE PERIOD. NET RESULT WILL BE FOR A SHARPENING FRONTAL

ZONE ACROSS WRN AR/ERN TX BY 18Z BEFORE SURGING ACROSS THE LOWER MS

VALLEY DURING THE OVERNIGHT HOURS. EARLIER THOUGHTS WERE

MOISTURE/INSTABILITY WOULD BE A BIT MEAGER TO SUPPORT ORGANIZED

SEVERE THUNDERSTORMS. HOWEVER 00Z GUIDANCE SUGGESTS SUFFICIENT

BOUNDARY LAYER MOISTENING WILL OCCUR AHEAD OF THE COLD FRONT SUCH

THAT SFC-BASED INSTABILITY WILL EASILY BE ATTAINED ALONG/AHEAD OF

COLD FRONT...POSSIBLY AS EARLY AS 17-18Z. GIVEN THAT DEEP LAYER

SHEAR WILL EASILY SUPPORT ORGANIZED ROTATING UPDRAFTS...IT APPEARS

THE THREAT FOR EMBEDDED SUPERCELLS ALONG A FORCED FRONTAL SQUALL

LINE WILL BE POSSIBLE. LATEST THINKING IS DAMAGING WINDS WILL BE

THE PRIMARY SEVERE THREAT DUE TO THE EXPECTED LINEAR STRUCTURE.

EVEN SO STRONG LOW LEVEL SHEAR AND LOW LCL HEIGHTS FAVOR AT LEAST A

THREAT FOR ISOLATED TORNADOES. PROGRESSION OF ORGANIZED SEVERE

SHOULD BE LIMITED BY WEAKER BUOYANCY OVER ERN MS/SWRN AL.

..DARROW/SMITH.. 11/26/2011

[andyhb]

00z NAM shows rather impressive instability across S/Central LA Saturday afternoon/evening...

[DoctorMu]

Check the local area Canadian Global 4 panel maps on the PSU e-Wall. I'm fairly certain this time of the year surface temps won't support anything significant, but extreme East Texas and parts of Louisiana would seem to have favorable thicknesses and moisture to mix in some snow IF the Canadian verified.

Ah, the old reach around!

[Srain]

Still a ways out in guidance and we know the models have struggled beyond the 3 day time frame, but to see the HPC Morning Update even chatting about the potential of wintry weather mischief late next week does raise an eyebrow...

WET SNOW REMAINS POSSIBLE ACROSS THE EASTERN GREAT LAKES/UPPER

OHIO VALLEY EARLY ON WITHIN THE EASTERN CYCLONE COMMA HEAD UNTIL

THE SYSTEM EXITS INTO CANADA DURING THE DAY WEDNESDAY. IN ITS

WAKE...STRONG HIGH PRESSURE WEDGES INTO THE PLAINS LATE WEDNESDAY

THROUGH FRIDAY WHICH SHOULD LEAD TO UPSLOPE SNOWS ACROSS MONTANA

AND WYOMING LATE WEDNESDAY INTO THURSDAY BEFORE THE HIGH MOVES OFF

TO THE SOUTHEAST AND WEAKENS. INCREASING HIGH PRESSURE ACROSS THE

INTERIOR WEST SHOULD LEAD TO OFFSHORE FLOW NEAR THE WEST COAST

BEGINNING THURSDAY AND CONTINUING INTO NEXT SATURDAY.

HOWEVER...NEAR THE CORE OF THE NEW CLOSED LOW DROPPING THROUGH THE

WEST LATE NEXT WEEK... MODERATE SNOWS ARE EXPECTED ACROSS THE

GREAT BASIN/SOUTHWEST/POSSIBLY THE SIERRA NEVADA LATE NEXT WEEK.

DEPENDING UPON HOW FAR EAST THE DEEP CYCLONE ACROSS THE WEST

TRACKS...SNOW IS ALSO A POSSIBILITY FROM FAR NORTH TEXAS INTO

SOUTHWEST KS NEXT FRIDAY. MODERATION OF THE ARCTIC AIR AND A MORE

ESE LOW INTO THE SOUTHERN HIGH PLAINS LEVEL FLOW SHOULD REDUCE THE

THREAT OF SNOW IN THAT AREA BY NEXT SATURDAY. A WEAK SYSTEM

CROSSING THE GREAT LAKES/NORTHEAST SHOULD ALSO DROP A STRIPE OF

LIGHT SNOW JUST N OF ITS TRACK FROM FRIDAY INTO SATURDAY.

[Srain]

KAMA 261453Z 35034G49KT 10SM SCT028 02/M04 A3024 RMK AO2 PK WND 34049/1453 SLP235 T00221044 53031

[Srain]

SPECIAL WEATHER STATEMENT

NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX

1031 AM CST SAT NOV 26 2011

TXZ200-213-214-226-227-235>238-262000-

LIBERTY-HARRIS-CHAMBERS-WHARTON-FORT BEND-JACKSON-MATAGORDA-

BRAZORIA-GALVESTON-

INCLUDING THE CITIES OF...LIBERTY...CLEVELAND...DAYTON...

HOUSTON...PASADENA...KATY...TOMBALL...HUMBLE...WINNIE...

MONT BELVIEU...ANAHUAC...EL CAMPO...WHARTON...PIERCE...

SUGAR LAND...MISSOURI CITY...RICHMOND...ROSENBERG...EDNA...

BAY CITY...PALACIOS...PEARLAND...LAKE JACKSON...ALVIN...

ANGLETON...FREEPORT...LEAGUE CITY...TEXAS CITY...FRIENDSWOOD...

GALVESTON

1031 AM CST SAT NOV 26 2011

...BRIEF FUNNEL CLOUDS POSSIBLE OVER THE SOUTHERN HALF OF SOUTHEAST

TEXAS THROUGH EARLY AFTERNOON...

BROADCAST MEDIA IS REPORTING A COUPLE OF SIGHTINGS OF FUNNEL

CLOUDS SINCE 10AM...ONE NEAR PEARLAND AND ONE OVER WEST HOUSTON.

GIVEN THE UNSTABLE AIRMASS IN PLACE...A FEW BRIEF FUNNEL CLOUDS

ARE POSSIBLE OVER THE SOUTHERN HALF OF SOUTHEAST TEXAS THROUGH

EARLY AFTERNOON. THE FUNNEL CLOUDS ARE UNLIKELY TO TOUCH THE

GROUND.

[#NoPoles]

ok, be honest...how many people in Houston are running around naked enjoying the rain?

Steve?

[Srain]

ok, be honest...how many people in Houston are running around naked enjoying the rain?

Steve?

We are sensible folk down here and tend not to run around naked when 60F outside. After all, it is the cold and flu season...

Now if this was of the frozen variety, it might be a different sorry...

[#NoPoles]

We are sensible folk down here and tend not to run around naked when 60F outside. After all, it is the cold and flu season...

Now if this was of the frozen variety, it might be a different sorry...

how much in your rain gauge?

i heard it might snow soon...pics??? hahahahahahaha!

[Srain]

how much in your rain gauge?

i heard it might snow soon...pics??? hahahahahahaha!

I have over an inch here, but some locations to my N and W are over 2 inches. Needless to say we are happy. Late next week could provide for some wintry mischief for NM/TX/OK. We will see...

[TrekkerCC]

I have over an inch here, but some locations to my N and W are over 2 inches. Needless to say we are happy. Late next week could provide for some wintry mischief for NM/TX/OK. We will see...

Not sold on the snow, yet. GFS/EURO, which showed a cut-off upper level low barreling through Texas in earlier runs, in this morning runs have gone for a more progressive upper-level trough passage. Given that DFW area missed big rains to the west (earlier this fall) or to the east (last few events), I'm quite skeptical we will be in the target zone, even if a winter event does develop, at least for now. It does bear watching, as I never would think a fall cutoff upper level low would cause potential snow for many areas in the SE this early in the season.

[Cypress]

a lovely rainy day in SE TX

http://www.harriscountyfws.org/

http://www.wrh.noaa.gov/mesowest/gmap.php?zoom=4&extents=4.390229,-132.626953,54.876607,-59.677734&density=1&precip=1

[Ed Lizard]

probably the last rain for at least 7 days, glad we got it.

[Srain]

There are a lot Freeze/Hard Freeze Warning up already for S Central TX this morning. I wouldn't be surprised to see at least Freeze Watches extended E for parts of SE TX tonight. It looks like we've done much better in the rainfall department for the month of November with these U/L's dropping S into the Baja Region all month. It's been an interesting month in a rather strange pattern for a La Nina year and if this trend continues into December, just maybe we can put a dent in this drought. We will see...

[Ed Lizard]

GFS and ensembles suggest a pretty deep, but positive tilt trough for next weekend into early the first full week of December.

I'm a fan of negative tilted troughs myself, but operational shows rain for Central Texas in that time period...heading for SETX at the chop.

Not looking like a Winter event for all/most of Texas from the op GFS.

[Srain]

Morning e-mail from Jeff:

Freeze warning verifying across the region this morning with several sites at or below freezing across SE TX, the coastal bend, and SC TX. In fact many locations are colder here than in Montana currently!

700am Temps:

Conroe: 30

College Station: 32

Hobby: 33

Victoria: 29

Port Lavaca: 32

Corpus Christi: 28

Austin: 31

Large polar surface high centered over SW TX will maintain NW winds today keeping the cool-cold air mass in place even under sunny skies. Highs will only reach the mid to upper 50’s under NW winds of 5-10mph (much less than the 30-40mph Saturday night and Sunday). Cold again tonight with lows back near/below freezing especially north of HWY 105, before better warming on Tuesday. Next front will cross the region dry on Tuesday evening helping to keep the cool-cold air mass locked in place through mid week with lows in the 30’s and highs in the 50’s/60’s.

Surface high will begin to move eastward late in the week as the next strong upper level trough breaks off from the main polar jet and digs itself into the SW US by Friday. Models are having a tough time resolving the evolution and movement of this feature which in turn is greatly influencing the upcoming late week/weekend forecast downstream over TX. While this system slows and potentially cuts-off over NW MX late this week a strong polar cold front will drop southward behind a northern stream short wave into TX late Thursday into Friday. Upper level SW flow aloft does not support this front making good headway southward across the state, but a very cold dense air mass behind this front will likely help push the boundary further south than models show. SW flow aloft over the boundary will result in quick lifting of a moist air mass over the surface boundary with clouds and drizzle/light rain developing in the cold post frontal air mass. Main question is how far south does this front move before it stalls. Combination of developing lower TX coast surface trough in response to incoming SW US energy does support a little more southward draw of this front along with its cold dense air mass, but not sure it will make the coast. For now will hang it up along a line from west of Corpus to north of Victoria to College Station (this is a very low confidence forecast with large potential for temperature error). Locations north and west of the front will stay in the 40’s while areas south and east of the front will be in the 50’s/60’s.

Not overly impressed with the rain chances ahead of this front, with better chances appearing behind the boundary with isentropic lift over the cold dome ahead of the approaching SW US trough. When this trough ejects eastward and how fast will determine when the best rain chances develop over the weekend. For now will show increasing cold rains Saturday into Sunday from west to east across the region. Profiles over SE TX support all rain while locations from west TX to OK will likely deal with some kind of P-type issues in the Fri-Sun period.

[Ed Lizard]

As much as everyone hates cold weather unless it is accompanies by winter precip, I have to cheer on the GFS solution of a deep trough inducing a coastal low with serious rains inland in the cool air next weekend.

[DoctorMu]

As much as everyone hates cold weather unless it is accompanies by winter precip, I have to cheer on the GFS solution of a deep trough inducing a coastal low with serious rains inland in the cool air next weekend.

Yeah, I'll take as much of the wet stuff as possible, regardless of form or temp.

[Srain]

The Euro/Canadian/UKMET suggest a slower progression of the front/trough and keep the 5H low back to the W. It certainly could lead to another decent rainfall event in the 'warm' air. Further N and W, wintry precip chances does appear to be increasing.

[andyhb]

Any potential strengthening/underestimation of the moisture return off the Gulf for Saturday afternoon/evening and we could have svr problem across Central/E Texas and then the Lower MS Valley/TN Valley into Sunday...

[Srain]

Morning e-mail from Jeff:

Another clear and cold morning across the region with temperatures currently in the low to mid 30’s

Secondary surge of colder air will arrive today from the north with winds briefly increasing out of the NW of 10-15mph. This surge will help reinforce the cold and dry air mass already in place and continue to yield lows in the 30’s and highs in the 60’s today and Wednesday. 1025mb surface high pressure dome will shift eastward Thursday allowing SE winds to return to the region, but moisture return will be slow as the air mass over the Gulf has been scoured by the recent cold frontal intrusion. While out west a piece of energy will break off from the northern jet stream and dig southward into the SW US cutting off from the main polar jet stream and upper air flow across the US (a SW US cut off low). The polar stream short wave will continue eastward dragging a strong polar boundary into TX late this week. Unfavorable SW flow aloft due to the digging trough over the SW US and the departing northern stream trough does not support a significant frontal push across TX. In fact the models may be coming into some weak agreement on stalling the boundary across SW to NC TX this weekend. While this may be what the models are suggesting, cold dense air masses tend to bleed southward undercutting unfavorable flow aloft (but how far south) if the question that is nearly impossible to answer. Currently thinking is that the front will stall north and west of SE TX so a gradual warming and moistening trend into the weekend.

Next big item is when and how (what form) does the SW US energy eject into the southern plains. GFS brings the system through the fastest and opens the low as it moves across while the ECMWF and CMC both eject a piece and then quickly reform a secondary upper low again back over the SW US early next week. GFS solution would result in a good shot a rainfall over the weekend followed by a strong polar front through the area and off the coast early next week with some very cold temperatures possible behind the late weekend front. The ECMWF and CMC would support a much warmer and slower frontal passage and then a period of overrunning into early next week as the secondary energy hangs back to the west. Each of the models have been somewhat consistent in their own handling of the weekend storm system, but none on the same page. Ensembles do support more of the progressive GFS solution and most NWS offices are falling in line with that thinking at the current time.

With this reasoning in mind will go with increasing rain chances late Friday into Saturday as the SW US storm forces downstream pressure falls and a rapid influx of Gulf moisture. Rain chances will likely peak over SE TX Saturday afternoon-Sunday near/behind the polar frontal boundary. It should be noted that the best rain chances will be over central and north TX where additional much needed rainfall appears fairly likely late Thursday-Sunday. This is an overall low confidence forecast and some big changes could result over the next few days.

[Srain]

The 12Z Euro trended slightly with what the GFS and Canadian offered today in suggesting a bit of shearing out of the SW upper air disturbance before dropping another 5H (upper low) in the Desert SW. Also of note, the Euro is beginning to come around to the idea of colder weather dropping S behind the front and setting the stage for another possible freeze event early next week. This is all subject to change, but this does bode well with a little better agreement in model world in regards to what could happen as we look ahead. It still appears a Winter Storm is shaping up for the Central/Southern Rockies into the Panhandle of TX and points NE over the weekend. We will see…

[Srain]

A very complicated forecast is shaping up for late week into early next week. The guidance continues to differ in the handling of the various features and where frontal boundaries will stall and with the upper air disturbances to our W in AZ. The best guess is moisture and clouds will begin to increase late Thursday across the Lone Star State as high pressure moves E and pressures falls to our W. The northern stream will send a cold front S into TX Thursday night/Friday morning and a 500mb mid/upper low cuts off in the Desert SW. Over running rains and even wintry mischief is possible across W TX and parts of the Permian Basin, N of the Hill Country. The NAM is coming in with much colder air in that region while the GFS is not as cold. The Euro/Canadian models suggest the Upper Low will linger over AZ throughout the weekend. It does appear that showers and even a few storms could be possible late Saturday into Sunday for our area as the cold front finally sags S into our region. Over running light rain is possible behind the front with a SW flow aloft and a shallow layer of cold air until the upper air disturbance to our W ejects E. Winter Weather conditions are possible throughout the weekend for N MX, parts of W TX and the Panhandle and even as far S as Abilene. Things look to finally clear out early next week with even colder weather possible in the long range. We will see...