November 2015: Ending Cold & Rainy

[tireman4]

Holy Moly...that is some freeze..but I am sure it will modify...LOL

[jasons2k]

What a beautiful November day it is today! Enjoy it while it lasts

[srainhoutx]

The 12Z Euro suggests a 1050+mb Arctic High building across Western Canada as well as another deep Western trough and attending storm system dropping S from the Pacific NW with the Arctic boundary. The sub tropical jet is also very noisy with embedded disturbances headed NE towards Mexico and toward Texas with a SW flow aloft.

[tireman4]

Have you made your famous "Stepping Down" phrase on here yet, Srain?

[harpman]

Have you made your famous "Stepping Down" phrase on here yet, Srain?

Yes, he did earlier.

[srainhoutx]

The afternoon Updated Climate Prediction Center Day 11+ Outlook is out. It is interesting to see December 5, 2009 now showing up in the analogs.

[snowman65]

how does this correlate to to possible hard freeze after thanksgiving? Maybe I just dont know how to read these charts...

[srainhoutx]

The 12Z GFS suggests a very cold Arctic High settling into the Plains on Saturday/Sunday as we end the busy Thanksgiving Holiday travel period. The GFS also suggests a land falling Eastern Pacific tropical cyclone along the West Coast of Mexico as the cold air is entrenched across the Lone Star State. There are also indications of a Coastal trough/low organizing near Brownsville. While this is still a ways out, the teleconnection indices continue to advertise a very -EPO and a + PNA regime which tends to build a Ridge into Alaska allowing a chunk of very cold air to drop South from Siberia into Western Canada and into the Plains.

[sambucol]

Any idea of what the temps will be Thanksgiving week and Thanksgiving day?

[srainhoutx]

Any idea of what the temps will be Thanksgiving week and Thanksgiving day?

The GFS suggests a light freeze/frost possible next Monday then warming up to near 80F for Thanksgiving Day. The bottom falls out the Saturday after Thanksgiving Day and struggles to reach the low 40's for highs and near 30 for lows as we end November and begin December. Still a long way out, so expect changes as we get closer.

[srainhoutx]

The 12Z Euro suggests a deep Western trough and Arctic cold front arriving across the Panhandle a week from Saturday as a land falling tropical cyclone strikes the West Coast of Mexico. The Arctic boundary pushes South on Sunday with a very unsettled SW flow aloft and associated tropical moisture in the mid/upper levels arriving across Texas Saturday night into Sunday the 29th.

[srainhoutx]

HGX 'hinting' at a possible Freeze Watch Sunday for early Monday...

AIRMASS BEHIND THIS FRONT IS COLD SO EXPECT MIN TEMPS SUNDAY
MORNING TO BE IN THE 30S/40S WITH WINDS AND MOIST GROUNDS KEEPING
MIN TEMPS HIGHER. MIN TEMPS ON MONDAY MORNING SHOULD BE COLDER IN
THE LOW 30S FOR MUCH OF THE AREA AS HIGH PRESSURE BUILDS OVER THE
AREA. MOST OF THE AREA HAS A REALLY GOOD CHANCE AT A FREEZE SO
WILL HAVE TO MONITOR FOR A FREEZE WATCH. RIGHT NOW BEST ODDS OF A
FREEZE WILL LIKELY BE NORTH OF I-10 LINE BUT COULD BE SOME OTHER
RURAL OUTLYING AREAS THAT REACH FREEZING CLOSER TO THE COAST.

[srainhoutx]

Cold air and a land falling tropical cyclone along the West Coast of Mexico theme continued with the 18Z GFS.

[ticka1]

from those panels (and i know it will change) how cold?

[srainhoutx]

from those panels (and i know it will change) how cold?

Cold enough for ice across portions Central and N Texas. As you stated, we have a week to watch all this wintry nonsense unfold, if it is going to...

[srainhoutx]

Evening briefing from Jeff:

Extremely active weather pattern likely over the next 7-14 days.

Strong cold front will sweep across the area early Saturday with rapidly falling temperatures during the day.

Potential arctic air outbreak the weekend after Thanksgiving

If we thought the last few weeks were active…hold on! Upper air pattern will undergo strong amplification with cold arctic air mass currently over Alaska becoming increasingly dislodge and sent southward. A piece of this air mass will arrive this Saturday before potentially the entire air mass dumps down the front range of the Rockies just after Thanksgiving.

Moisture return is underway this afternoon and expect clouds to develop from south to north tonight. Moisture increases more on Friday and weak isentropic lift is expect to help force a few showers by afternoon. Strong cold front will blast into TX Friday night and move off the coast between 600am and noon on Saturday with temperatures falling from the 60’s into the 40’s with very strong north winds. Expect strong lift with the front to produce numerous showers and even elevated thunderstorms Friday night. Models continue to trend wetter and wetter with this system and now show possibly 1-2 inches of rainfall across the region especially in areas of banded heavier thunderstorms.

Big news will be the temperature fall as cold Canadian air mass slices into the region. NW winds post front will howl with impressive 5-7mb pressure rises over the region as large 1043mb high pushes down the plains into OK. Expect winds on Saturday sustained of 25-35mph with gusts of 40-45mph which will drive wind chills into the lower 40’s and 30’s. Gale Warnings will be needed for most if not all waters as the cold air mass strikes the warm waters…expect gusts to 50mph or even greater offshore into Saturday night. Skies will clear rapidly Saturday afternoon and this will result in temperatures falling into the 30’s for most locations Sunday morning. Think winds will stay up enough to prevent a freeze for most areas…but N and W areas could be close.

Cool on Sunday with highs only in the mid 50’s even with much sun. Big concern is Monday morning with clear skies and calm winds along with dewpoints in the upper 20’s. Looks like we may see a widespread freeze north of I-10…which would require a freeze watch since it would be the first killing freeze of the season. Areas north of HWY 105 look more certain to have a freeze and will need to take the needed precautions with respect to tender vegetation.

Monday-Thursday:
Southerly flow to return to the region with active sub-tropical jet overhead. Clouds will increase late Monday…and do not expect the sun for the next several days after that. Will bring rain chances into the forecast Tuesday-Friday, but certain days will have better chances as disturbances move across in the sub-tropical flow aloft..it will not rain the whole time…but there will be periods of rain and thunderstorms. Temperatures will be mild as southerly flow is maintained with lows in the 50’s and 60’s and highs in the 70’s.

Long Range (Black Friday-weekend after Thanksgiving):
Upper air pattern undergoes strong amplification with massive forecasted 1058mb arctic high pressure cell dropping southward out of NW Canada. Cold arctic air mass looks poise to tumble down the plains and through TX with very cold temperatures. EPAC tropical cyclone looks to be drawn NE into this very cold air mass (I have never seen an EPAC tropical system be pulled over an arctic air mass) with all kinds of precipitation. Forecast profiles are all over the place between models and model runs, but intensity of cold air mass would likely result in some degree of P-type considerations across portions of TX. This is still a good ways off and subject to significant changes over the next several days…but something to certainly be watching.

[Katdaddy]

Another nice day before increasing clouds and rain chances tonight ahead of a strong cold front that will blast off the coast around noon Saturday. Expect rapid clearing and strong gusting N/NW winds especially along the coastal areas. Gale Warnings along the coast and offshore will likely be required tomorrow and Freeze Watches and Warnings Sunday afternoon for inland portions of SE TX as temps drop into the low 30s Monday morning.

[srainhoutx]

Our first shortwave ushering in the coldest air of the season is pulling out of the Rockies into the Plains with a myriad of winter weather advisories and winter storm watches hoisted into the Great Lakes Region. The front will rapidly advance South today arriving tomorrow.

TS Rick in the Eastern Pacific should begin to weaken and spread to high and mid level clouds across Mexico into Texas by next Tuesday as attention turns both North and West to a bigger slug of colder air over Western Canada being dislodged and a developing tropical cyclone South and West of the Gulf of Tehuantepec. That Eastern Pacific moisture will be our major weather maker for Thanksgiving as well as the arrival of the next Arctic Boundary as yet another pesky Western Trough organizes in the Great Basin.

[srainhoutx]

The morning Updated Extended Outlook from the Weather Prediction Center is offering clues as to what we can expect for Thanksgiving. Also, the 12Z GFS is indicating a tropical cyclone lurking off the West Coast of Mexico as the Arctic boundary begins to advance toward Texas Thanksgiving Day.


EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1100 AM EST FRI NOV 20 2015

VALID 12Z MON NOV 23 2015 - 12Z FRI NOV 27 2015

...WHITE THANKSGIVING LIKELY FOR MUCH OF THE CENTRAL/NORTHERN
ROCKIES INTO THE PLAINS...

...MUCH COLDER TEMPERATURES FOR THE WESTERN HALF OF THE COUNTRY...


...OVERVIEW...

SEESAW IN THE HEIGHT PATTERN WILL PLAY OUT NEXT WEEK OVER THE
LOWER 48. INITIAL MODEST RIDGING IN THE WEST AND TROUGHING IN THE
EAST WILL REVERSE ITSELF BY WEDNESDAY AS A STRONG UPPER LOW DIGS
SOUTHWARD THROUGH THE INTERMOUNTAIN WEST. THIS IS IN RESPONSE TO
ANOTHER UPSTREAM TROUGH/RIDGE COUPLET ACROSS ALASKA AND THE
NORTHEAST PACIFIC INTO WESTERN CANADA. MODELS AND ENSEMBLES REMAIN
IN GOOD AGREEMENT ON THE LONGWAVE EVOLUTION AND EVEN SHOW BETTER
AGREEMENT THAN 24 HRS AGO WITH SOME DETAILS, THOUGH THOSE CAN AND
OFTEN DO CHANGE. THIS PATTERN SUPPORTS A SIGNIFICANT DUMP OF COLD
AIR THROUGH THE WESTERN STATES WITH WINDY AND SHOWERY/SNOWY
CONDITIONS FOR MANY AREAS LEADING INTO THE VERY BUSY TRAVEL DAYS
AND THANKSGIVING ITSELF.


...GUIDANCE EVALUATION/PREFERENCES...

FOR THE FIRST PART OF THE FORECAST, MON-WED, A MODEL/ENSEMBLE
CONSENSUS BLEND OFFERS A REASONABLE STARTING POINT ACROSS THE
CONUS. ECMWF LIES ON THE STRONGER SIDE WITH MID-LEVEL SHORTWAVE
ENERGY PUSHING INTO CALIFORNIA BUT THEN WEAKENING MON-TUE BUT
OTHERWISE FALLS WELL WITHIN THE ENSEMBLE SPREAD ALONG WITH THE
06Z/00Z GFS. TROUGH SWINGING OFF THE EAST COAST WILL SUPPORT A
SURFACE LOW ALONG THE FRONTAL BOUNDARY ON MONDAY THAT SHOULD STAY
JUST OFFSHORE WITH ITS PRECIP SHIELD, EXCEPT FOR MAYBE CAPE COD
AND ALONG I-95 NORTHWARD INTO MAINE. IT WOULD NOT TAKE MUCH TO
NUDGE THIS FARTHER WEST BUT THE ENSEMBLE CONSENSUS TILTS TOWARD
KEEPING THE PRECIP OFFSHORE FOR NOW.

IN THE WEST, DETERMINISTIC MODELS HAVE CONVERGED ON KEEPING A MORE
COHERENT UPPER LOW IN THE WESTERN STATES INTO NEXT FRIDAY RATHER
THAN SENDING ENERGY THROUGH THE PLAINS AROUND THURSDAY, REFLECTED
AS A STRONGER AREA OF SURFACE LOW PRESSURE. LEAD COLD FRONTAL
BOUNDARY WILL BRING WITH IT THE COLDER AIRMASS OF THE SEASON INTO
THE REGION WEST OF THE DIVIDE EARLY IN THE WEEK. CANADIAN
ENSEMBLES SHOW MORE TROUGHING THAN 24 HRS AGO BUT ARE STILL
WEAKER, THUS AFFECTING THE NAEFS MEAN. ARCTIC FRONT ON ITS HEELS
IS FORECAST TO CATCH UP TO THE FIRST BOUNDARY AROUND WED-THU AS
THE EASTERN EDGE SLOWS ITS PROGRESS THROUGH MN/WI/IA. THIS WILL
SET UP A GOOD UPSLOPE AN OVERRUNNING EVENT FOR THE UPPER MIDWEST
BACK THROUGH THE HIGH PLAINS INTO THE CENTRAL/NORTHERN ROCKIES
TUE-THU. UPSTREAM, ENSEMBLES ARE HAVING A TOUGH TIME WITH THE
BLOCKY NORTH PACIFIC FLOW BUT PREFER TO KEEP THE RIDGE IN PLACE
OVER BRITISH COLUMBIA THROUGH THE WEEK, THOUGH PERHAPS TILTED
EASTWARD, PER THE 00Z ECMWF/ECENS MEAN AND 06Z GEFS MEAN RATHER
THAN EAT INTO IT OR DESTROY IT PER THE 00Z/06Z GFS, RESPECTIVELY.
TIMING OF THE FRONT REMAINS A CHALLENGE AS THE COLD AIR RUSHES
SOUTHWARD EAST OF THE TERRAIN IN CO AND WESTERN KS/NE. ECMWF MAY
BE TOO SLOW WITH THE FRONT GIVEN THE COLD AIRMASS. THUS, A TREND
TOWARD THE 00Z GEFS/ECENS MEAN WAS INCORPORATED TO IRON OUT SOME
DETERMINISTIC DIFFERENCES.

...SENSIBLE WEATHER HIGHLIGHTS...

COLD, SNOW, AND WIND WILL AFFECT MUCH OF THE NORTHERN/CENTRAL
ROCKIES AS THE LEAD BOUNDARY PASSES BY, ACCENTUATED BY THE ARCTIC
FRONT. TRAVEL WILL BECOME MORE DIFFICULT WITH BLOWING SNOW LIKELY
IN THESE REGIONS. WIND CHILL TEMPERATURES ON WED-FRI WILL BE BELOW
ZERO FOR A SIZABLE AREA OF WY/MT/ID. SNOW TREAT WILL SPREAD INTO
THE HIGH PLAINS BY FRIDAY AS THE FRONT SINKS SOUTHWARD AND A BIT
EASTWARD. TEMPERATURES ARE FORECAST TO BE 10-25F BELOW AVERAGE
OVER THE ROCKIES/HIGH PLAINS. TEMPS MAY NOT THREATEN DAILY RECORDS
BUT WILL STILL FEEL QUITE COLD GIVEN THE ROCKIES/PLAINS HAVE
AVERAGED ABOVE NORMAL FOR THE MONTH THUS FAR. AS THE LEADING COLD
FRONT BEGINS TO INTERACT WITH GULF MOISTURE, WARM SECTOR RAINFALL
SHOULD INCREASE IN COVERAGE/INTENSITY BY THE LATTER HALF OF THE
WEEK

FRACASSO/RAUSCH

[srainhoutx]

It's still a week out and these computer models will change daily, but like Jeff mentioned last evening I too cannot recall a tropical cyclone making landfall in Western Mexico and its deep tropical moisture being entrenched across our Region after an Arctic front has arrived in my 45+ years of following Texas Weather.