December: Warm Days & Cool-Foggy Nights To End 2011

[Katdaddy]

Onward to December. Ready for the cold.

[srainhoutx]

The 12Z Operation Euro and GFS Ensembles suggest it will begin to cool down as we begin December. It does appear that a +PNA regime (ridging along the W Coast and up into the Gulf of Alaska) will become established. The Alaska vortex that has been responsible for record breaking cold looks to weaken and relax and just perhaps a flow across the Arctic will replace the flow off the Pacific that we have seen for almost a month. We will see.

[redneckweather]

What's the long range showing going into the first weekend in December? I'm heading up to central Texas that Friday morning for a deer hunt. I'm hoping for cold weather.

[wxman57]

What's the long range showing going into the first weekend in December? I'm heading up to central Texas that Friday morning for a deer hunt. I'm hoping for cold weather.

What dates in particular? I'm seeing anything from quite cold to warm to rainy to dry for that first week. A real mix of weather.

[redneckweather]

wxman, I'm heading out on Dec 2nd and staying thru the 4th (Sunday). Thanks!!

[srainhoutx]

The 12Z Euro would make for an interesting weekend deer hunt...if it verified...

[wxman57]

wxman, I'm heading out on Dec 2nd and staying thru the 4th (Sunday). Thanks!!

Still quite a ways out to be certain, but it currently looks like return flow off the Gulf begins late next Thursday. That means warming temps and increasing clouds for TX on Friday. Probably highs in the 70s by Friday. Lows in the mid to upper 50s Saturday with highs in the 72-75 deg range. Cloudy. Maybe a few light sprinkles around. Possibility of a weak reinforcing cold front on Sunday morning, but I have little confidence in the model output that far out as far as that front.

[redneckweather]

Man, I sure hope it will get a bit colder than that wxman. I sure appreciate the analysis. If you see any changes, let me know if you can.

I hope everyone had a great Thanksgiving!!!!

[redneckweather]

I see most discussions from the NWS offices mentioning a strong front next Thursday. This is a piece from the Corpus office. Thoughts?



LOW CONFIDENCE FORECAST FOR THURSDAY BUT 00Z CAN/ECMWF
SHOW POSSIBILITY OF POLAR AIRMASS SURGE INTO THE SOUTHERN PLAINS
THAT COULD REACH THE REGION THURSDAY NIGHT.

[srainhoutx]

The 12Z GFS does advertise a strong cold front next Thursday. There has been a trend to cut off an upper low to our W that does give some pause, but that could mean clouds and a chilly light rain, if that were to verify. We'll see what the other guidance offer, but as we have seen for a while now, the models have been rather inconsistent beyond 3-5 days. We will see...

[srainhoutx]

A snip from Oklahoma City regarding next weekend:

THE MODELS MOVE BACK INTO BETTER AGREEMENT BY MID
WEEK...AND PREDICT A SPLIT FLOW PATTERN THAT IS BECOMING MORE
PRONOUNCED. THE NORTHERN STREAM IS SET TO DUMP A DECENTLY COLD AIR
MASS HERE BY LATE NEXT WEEK...WHILE ANOTHER CLOSED LOW FORMS IN THE
SOUTHERN STREAM OVER CALIFORNIA. INTERPOLATING FORWARD...WE COULD
HAVE OUR FIRST RUN-IN WITH WINTER PRECIPITATION TYPES BY NEXT
WEEKEND.



From Lubbock:

THINGS GET MORE INTERESTING WEATHER WISE AS WE HEAD INTO THE MID AND
LATTER PARTS OF NEXT WEEK. ECMWF/GFS ARE FAIRLY SIMILAR NOW IN THEIR
MID LEVEL FLOW SOLUTIONS INTO NEXT WEEKEND. NORTHERN AND SOUTHERN
STREAM ENERGY WILL PHASE INTO A CLOSED LOW OVER THE TENNESSEE VALLEY
BY SUNDAY NIGHT AND THEN ADVECT NORTHEAST INTO ONTARIO BY MID WEEK.
THIS LEAVES MODERATE NORTHWEST FLOW OVER THE WESTERN TWO THIRDS OF
THE CONUS. BOTH MODELS SHOW WAVES IN FLOW NORTH OF REGION FORCING
COLD FRONTS SOUTH INTO WEST TEXAS ON TUESDAY AND AGAIN ON
THURSDAY...WITH THE THURSDAY AIRMASS THE COLDER OF THE TWO.
CONCURRENTLY...MID LEVEL FLOW WILL BUCKLE ACROSS WESTERN US AS MID
LEVEL JET ENERGY RACES SOUTHEAST FROM GULF OF ALASKA. BOTH MODELS
DEPICT THIS ENERGY CLOSING OFF A MID LEVEL LOW OVER NORTHERN BAJA BY
FRIDAY EVENING BEFORE EJECTING IT EAST AND NORTHEAST TOWARD THE
REGION FOR NEXT WEEKEND. OBVIOUSLY THIS IS SEVERAL DAYS AWAY...BUT
SIMILIARITY OF SOLUTIONS ADDS SOME CONFIDENCE TO THIS SCENARIO. IF
THE PATTERN DOES VERIFY IT IS ONE THAT COULD POTENTIALLY MEAN A
SOUTHERN ROCKIES SNOW STORM BUT IT IS WAY TOO EARLY TO LATCH ONTO
THAT. FOR NOW WILL SHOW AN INCREASE IN MOISTURE BY LATE WEEK AND IT
WILL BE SOMETHING WE NEED TO WATCH OVER THE NEXT SEVERAL DAYS.
OTHERWISE...DRY CONDITIONS WILL PREVAIL.

[redneckweather]

A Thursday evening/Friday morning frontal passage would be perfect from a deer hunting perspective. I appreciate the updates.

[srainhoutx]

HPC Morning Update:

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
303 AM EST SAT NOV 26 2011

VALID 12Z WED NOV 30 2011 - 12Z SAT DEC 03 2011

...WINTRY PATTERN FOR MUCH OF THE LOWER 48 THIS PERIOD...

AS WE HEAD INTO DECEMBER...TROUGHING ACROSS CENTRAL CANADA TEAMS
UP WITH RIDGING BUILDING ACROSS THE EASTERN PACIFIC JUST OFFSHORE
THE WEST COAST OF NORTH AMERICA SHOULD LEAD TO A POSITIVELY TILTED
TROUGH SPANNING THE CONTINENT FROM CENTRAL CANADA INTO THE WESTERN
UNITED STATES WITH HEIGHTS REBOUNDING ACROSS THE EAST. THE
GUIDANCE SHARES THESE IDEAS. DETAIL ISSUES CONTINUE TO ABOUND OUT
EAST...WHERE A COMPROMISE OF THE 00Z ECMWF/00Z UKMET MADE THE MOST
SENSE PER THE MODEL DIAGNOSTIC DISCUSSION /PMDHMD/. THIS
PREFERENCE WAS KEPT THROUGH LATE THURSDAY...THE END OF THE UKMET
RUN. THEREAFTER...THE 00Z GFS/00Z ECMWF WERE IN REASONABLE
AGREEMENT SO USED A COMPROMISE OF THOSE PIECES OF GUIDANCE LATE
THIS WEEK. THIS SET OF MODEL PREFERENCES MAINTAINED REASONABLE
CONTINUITY.

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 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 CLOSED LOW DROPPING THROUGH THE
WEST... 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 THE BIG COUNTRY OF TEXAS
NORTHWARD TOWARDS THE OKLAHOMA PANHANDLE NEXT FRIDAY AND SATURDAY.
A FRONTAL SYSTEM CROSSING THE NORTHERN PLAINS/GREAT
LAKES/NORTHEAST SHOULD ALSO DROP SOME SNOW FROM THURSDAY INTO
SATURDAY.

[srainhoutx]

The 12Z GFS has backed off on the cold air next weekend while the Euro has come in with a stronger front suggesting a surge of Polar Air sweeping S as yet another upper low passes by from our S and W. It does appear that some locations may see their first shot at some wintry mischief in parts of Texas. We will see...

[tireman4]

It does appear that some locations may see their first shot at some wintry mischief in parts of Texas. We will see

And so it begins. Woo Hoo. Bring on winter. Poor Wxman 57. He is gonna freeze at some parts this winter......LOL

[redneckweather]

I will take a little wintry precip mixed in with my deer hunt. I sure won't complain, that's for sure.

[srainhoutx]

It looks like the first weekend in December will bring a rather strong cold front into the Intermountain West/Plains region. The does appear to be a brief warm up for Wednesday/Thursday before that stronger front arrives. The fly in the ointment will be another cut off Upper Low in the Desert SW and just how fast that feature ejects E. If the low is progressive as the overnight GFS suggests, then a brief cold shot could be expected. The problem is the GFS has been a bit too progressive with the pattern of late and that tends to give some attention to the Euro/Canadian evolutions. That said, all the guidance has struggled with anything beyond 3 days, so we'll just have to see how things play out. It does appear we will have a brief 'warm up' on Thursday before the strong front passes. What remains to be seen, is what happens with that upper air disturbance to our W for next weekend...

HPC Morning Update:

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
911 AM EST SUN NOV 27 2011

VALID 12Z THU DEC 01 2011 - 12Z SUN DEC 04 2011

MODELS AND ENSEMBLES REASONABLY AGREE THAT LINGERING MID-UPPER
LEVEL TROUGHING OVER THE ERN US/CANADA THU EXITS INTO THE WRN
ATLANTIC AS POTENT NRN STREAM TROUGH ENERGY PROGRESSES FROM THE
N-CENTRAL TO ERN US THU-SAT...BRINGING WITH IT A SHOT OF COLDER
AIR OVER THE CENTRAL THEN ERN STATES. MEANWHILE... UNSETTLING AND
COOLING CLOSED LOW DEVELOPMENT OVER THE SWRN US THU SHOULD PERSIST
INTO NEXT WEEKEND.

FORECAST SOLUTION SPREAD AND UNCERTAINTY BECOMES MORE SIGNIFICANT
ALOFT THOUGH LATE WEEK INTO NEXT WEEKEND WITH THE EXTENT OF
DIGGING OF SUBSEQUENT NRN STREAM TROUGH ENERGY TO THE LEE OF A
BUILDING NERN PAC/CANADIAN WEST COAST RIDGE. AMPLIFIED FLOW
INCLUDING THE ECMWF AND ECMWF ENSEMBLES LEADS TO DIGGING MAIN
TROUGH ENERGY THROUGH THE W-CENTRAL US FRI-SUN. THIS COULD ALLOW
FOR SOME INTERACTION WITH THE SWRN CLOSED LOW NEXT WEEKEND AND
MORE OF A LONGWAVE TROUGH SETUP ACROSS THE CENTRAL US. SOMEWHAT
LESS AMPLIFIED NRN STREAM SOLUTIONS LIKE THE 06Z GFS AND GFS
ENSEMBLES INSTEAD ALLOW A MORE EWD PROGRESSION OF THE NRN STREAM
TROUGH INTACT ACROSS THE N-CENTRAL THEN NRN TIER OF THE
EAST-CENTRAL US...WITH LESS SWRN SYSTEM INTERACTION.

THE UPSTREAM RIDGE OVER THE NERN PAC LATE WEEK SEEMS AMPLIFIED
ENOUGH IN MOST GUIDANCE TO LEAN ON A MORE AMPLIFIED FLOW SOLUTION
DOWNSTREAM. ACCORDINGLY...UPDATED HPC PRELIM SURFACE
FRONTS/PRESSURES AND 500 MB PROGS HAVE BEEN PRIMARILY DERIVED FROM
THE 00Z ECMWF ENSEMBLE MEAN. THIS SOLUTION IS SIMILAR BUT NOT
QUITE AS AMPLIFIED AS THE OOZ ECMWF AND MITIGATES SOME OF THE LESS
PREDICTABLE SMALLER SCALE FEATURES CONSISTENT WITH GROWING
UNCERTAINTY OVER TIME.

[srainhoutx]

The guidance continue to advertise a strong cold front for late Thursday into Saturday, depending on what model you choose to believe is more correct. While the medium range models do agree that some Arctic/Canadian air will follow in the wake of the strong front, what remains to be seen is what happens to our W near Arizona and a deep Upper Low. There are some differences is just how and where this upper air feature will eject and begin to transition E. There is even some chatter this morning from San Angelo and Dallas/Ft Worth of some possible wintry mischief as overrunning conditions set up behind that front next Friday into Saturday. While this is still a long way out in model world and we know guidance has struggled beyond the 3 day time frame, it will be interesting to monitor as the temps are looking very chilly across TX/NM/OK behind this Polar front. Stay Tuned as they say. Another interesting week is ahead in the weather world...

[srainhoutx]

I'll post the morning e-mail from Jeff in this Topic as many are looking forward to what may be ahead for the weekend...

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.

[wxman57]

6Z GFS doesn't show any strong cold front. Weak reinforcing front in a few days then possibly another front arriving on Sunday morning, along with some rain. Canadian and Euro don't have any weak reinforcing front on Wed/Thu. Canadian does have a front moving slowly through on Sunday. Euro is slower with the front. See the meteogram I made off the 6Z GFS below: