New Year's Eve Weather

[Ptarmigan]

todays 12Z GFS shows nada.....back to the typical boring weather....

I hate it when it flip flops.

[srainhoutx]

Well the GFS may be flip flopping some, but the Canadian and Euro suggest things may get mighty interesting across TX and the Southern Plains. If those models verify, there well may be severe and even wintry weather in N TX/OK and points NE with a double low solution. Regardless, it does appear we have a wet mid week and possibly stormy New Years Eve/New Years Day ahead and very chilly behind that strong front. Also, a sight you won't see too often across the Gulf at this hour as strong surge of cold air has spread very far S into Mexico.

[srainhoutx]

Here are some afternoon thoughts from various NWS offices regarding mid and late week...Oh and New Orleans area has reported flurries off and on today...Hard Freeze Warning for our Nothern Counties as well for tonight...

Houston/Galveston...

RETURN OF GULF MOISTURE WILL RESULT IN A WARMING TREND BEGINNING
LATER ON MONDAY. ISENTROPIC LIFT AND MOISTURE WILL BE ENOUGH FOR A
CHANCE OF RAIN RETURNING BY MONDAY NIGHT WEST OF INTERSTATE 45 AND
AREA WIDE ON TUESDAY. THE BEST CHANCES OF RAIN IS EXPECTED TUESDAY
NIGHT AND WEDNESDAY AS A STRONG SHORTWAVE TROUGH MOVES ACROSS THE
STATE. THE MODELS DO DIFFER ON THE COLD FRONTAL PASSAGE FRIDAY AND
SATURDAY. FOR NOW WILL STAY WITH THE GFS BUT THE TIMING IS IN
DOUBT AT THIS TIME.



Lake Charles...

RAIN CHANCES WILL BE INTRODUCED TO THE FORECAST BY TUESDAY IN
RESPONSE TO SEVERAL SHORTWAVES EXPECTED TO MOVE ACROSS THE AREA
THROUGH MID-WEEK. THE BEST CHANCES FOR RAIN LOOK TO BE DURING THE
DAY ON WEDNESDAY...EXTENDING INTO WEDNESDAY NIGHT. INSTABILITY INDICATORS
SHOW THUNDER AND LIGHTNING COULD BE ASSOCIATED WITH THIS
SYSTEM...IN FACT WITH SOME MODEST SHEAR...COULD SEE ISOLATED
TORNADO THREAT.

A SIGNIFICANT COLD FRONT WILL MOVE ACROSS THE REGION ON SATURDAY.
LIKE THE WEDNESDAY EVENT...A SMALL CHANCE FOR SEVERE STORMS WILL
BE POSSIBLE. HOWEVER...LOW FORECASTER CONFIDENCE ON EXACT TIMING
AND INTENSITY OF THE WEATHER DUE TO MODEL INCONSISTENCIES.



Austin/San Antonio...

ABUNDANT LOW LEVEL MOISTURE WILL COMBINE WITH A PASSING UPPER
LEVEL TROUGH LATE MONDAY NIGHT INTO WEDNESDAY TO PRODUCE SHOWERS
AND THUNDERSTORMS ACROSS SOUTH CENTRAL TEXAS. MOST AREAS WILL
EXPERIENCE SOME LIGHT SHOWER ACTIVITY...HOWEVER...THE MOST
AFFECTED AREAS WILL BE THE NORTHERN HILL COUNTRY AND THE FAR
EASTERN COUNTIES. STORM TOTAL RAINFALL AMOUNTS COULD BE FROM A FEW
HUNDREDTHS TO QUARTER INCH FOR MOST PLACES. ISOLATED SPOTS ALONG
AND EAST OF I-35 COULD GET AS MUCH A THREE QUARTERS OF AN INCH.

A COLD FRONT IS EXPECTED TO MOVE ACROSS SOUTH CENTRAL TEXAS ON
FRIDAY. THIS SYSTEM IS LIKELY TO ONLY AFFECT THE NORTHERN PART OF
THE CFWA. RAINFALL AMOUNTS WILL BE LIMITED TO FEW HUNDREDTHS.
BEHIND THE FRONT...EXPECT A COLD AIR MASS AND DRY CONDITIONS FOR
THE FIRST WEEKEND OF 2011. THIS MAY RESULT IN A HARD FREEZE OVER THE
HILL COUNTRY LATE SATURDAY/MONDAY MORNING OF NEXT WEEKEND.


Corpus Christi...

.LONG TERM (TUESDAY THROUGH SUNDAY)...MODELS CONTINUE TO SHOW A
NEARLY SATURATED SFC-H7 LAYER BY TUE MORNING WITH A WARM FRONT IN
THE AREA. ISENTROPIC UPGLIDE AND LOW CONDENSATION PRESSURE DEFICITS
WILL PROVIDE THE INITIAL MECHANISM FOR PRODUCING PRECIP ON TUE.
MODELS SHOW THE BEST ISENTROPIC PATTERN SHIFTING NORTH WITH THE WARM
FRONT THROUGH THE DAY...HOWEVER STRONG MOISTURE CONVERGENCE REMAINS
ALONG THE COAST AS WINDS BECOME STRONG OVER THE MORE UNSTABLE GULF
IN ADVANCE OF THE NEXT LOW PRESSURE SYSTEM. THE COMBINATION OF THIS
PERSISTENT MOISTURE CONVERGENCE...A NEARLY SATURATE SFC-H7 LAYER AND
DYNAMIC LIFT ASSOC INITIALLY WITH A JET STREAK AND THEN PROVIDED BY
A STRONG S/WV TUE NIGHT AND EARLY WED WILL PROVIDE CONTINUED HIGH
SCT-LIKELY POPS ACROSS THE COASTAL PLAINS AND ADJACENT GULF WATERS
WITH POPS DROPPING OFF DRASTICALLY ACROSS THE FAR WEST. TIMING OF
THE S/WV AND STRONGEST DYNAMIC LIFT HAS BEEN UNCERTAIN DUE TO STRONG
INCONSISTENCY BETWEEN MODELS BUT THE SOLNS APPEAR TO BE SETTLING ON
A 6Z TO 18Z WED TIMEFRAME FOR THE BEST LIFT. THIS TIMEFRAME MAY END
UP BEING THE BEST CHC FOR PRECIP DESPITE MOS POPS KEYING MORE ON THE
ISENTROPIC EVENT EARLIER IN THE PERIOD AND WILL ALSO BE BEST CHC FOR
HEAVIER QPF AND SOME EMBEDDED TSTMS AS INSTABILITY INCREASES. IN
FACT...HIGHER CAPES AND SHEAR MAY PROVIDE A CHC FOR A FEW STRONG
STORMS OVER THE GULF WATERS TUE NIGHT AND EARLY WED AND SEVERAL
MODELS ARE NOW SHOWING 1/2" TO 1 INCH EVENT TOTAL QPF ACROSS THE NRN
COASTAL BEND AND THE GULF WATERS WHICH WOULD BE VERY WELCOME.

DEEPER MOISTURE WILL BE SCOURED OUT BY THE S/WV AND ALL THAT WILL
REMAIN WILL BE SFC-H9 MOISTURE. STRONG SRLY FLOW WILL DEVELOP IN
ADVANCE OF A VERY VIGOROUS UPR TROUGH DIGGING INTO THE ROCKIES.
MODELS HAVE HAD ALL KINDS OF TROUBLE FORECASTING THE EVOLUTION OF
THIS TROUGH AND THE ASSOC FROPA LATE IN THE WEEK. FOR NOW KEPT THE
LATE FRI NIGHT FROPA...HOWEVER GFS HAS GONE BACK TO A LATE FRI AFTN
OR EARLY EVENING FROPA WHILE THE ECMWF HAS PUSHED IT BACK LATER INTO
SAT. THE ECMWF ALSO SHOWS A MORE PROGRESSIVE AND DEEPER TROUGH INTO
THE WEEKEND WHICH BRINGS MORE DRY AND COLD AIR INTO THE REGION WHILE
THE GFS SHOWS A WEAKER FRONT...WITH AN EVENTUAL RETURN TO AN
OVERRUNNING PATTERN. SPLITTING THE DIFFERENCE FOR NOW BUT NOT
DEVIATING TO FAR FROM MOS GIVEN THE UNCERTAINTY.


Shreveport...

A FAST MOVING UPPER LOW
WILL BRING DEEP MOISTURE QUICKLY BACK INTO AREA EARLY TUESDAY.
ELEVATED INSTABILITY AND NEAR OFF THE CHART LOW LVL SHEAR...BUT
EXTREMELY STABLE IN LOW LVLS. FOR NOW...WILL KEEP AS SHOWERS IN
FCST...BUT IF TSTM POTENTIAL BECOMES REALISED...COULD CONTAIN
ACTIVE WX. LOOKING AT WRAPAROUND MOISTURE AT LEAST BRIEFLY INTO WED.
DEEP TROUGHING TO THE WEST WILL BRING A MORE CLEAR CUT TSTM EVENT
FOR FRIDAY...WITH THE APPROACH OF A STRONG COLD FRONT FRIDAY
NIGHT...UNSEASONALLY HIGH INSTABILITY...AND MODERATE
UNIDIRECTIONAL SHEER IN DEEP SW FLOW.

Dallas/Ft Worth...

A POWERFUL UPPER LEVEL TROUGH IS FORECAST TO DEVELOP ACROSS THE
WESTERN US WEDNESDAY AND THURSDAY. THIS WILL HELP INCREASE
SOUTHERLY FLOW OVER THE REGION WITH TEMPERATURES CONTINUING TO
CLIMB INTO THURSDAY. DEWPOINTS ARE ALSO LIKELY TO REACH THE MID
50S TO LOW 60S BY FRIDAY...SO LOWS WILL BE WELL ABOVE NORMAL
THURSDAY NIGHT. THE TROUGH IS FORECAST TO EJECT OUT INTO THE
PLAINS FRIDAY AND THIS SHOULD SEND A COLD FRONT THROUGH THE
REGION SOMETIME FRIDAY. MOISTURE/INSTABILITY LOOK HIGH ENOUGH FOR
A CHANCE OF THUNDERSTORMS ALONG THE FRONT...WITH BEST CHANCES
ACROSS THE EAST. UPPER PATTERN RESEMBLES ONE THAT PRODUCES WINTER
TIME SEVERE WEATHER ACROSS EAST TEXAS AND INTO THE LOWER
MISSISSIPPI RIVER VALLEY...SO WE WILL HAVE TO WATCH AND SEE
WHETHER THIS THREAT DEVELOPS AND CLIPS OUR EASTERN ZONES FRIDAY.

OTHERWISE...GFS FORECAST DIVERGES FROM THE PACK WITH RESPECT TO
THE EVOLUTION OF THE UPPER TROUGH ACROSS THE PLAINS THIS WEEKEND.
ECMWF/CANADIAN AS WELL OTHER GFS ENSEMBLE MEMBERS SHOW A STRONGER
VORT LOBE ROTATING THROUGH THE BASE OF THE TROUGH. SHOULD THIS
VERIFY WE WOULD SEE COLD TEMPS WITH THE FRONT AND WINTER PRECIP
WOULD ALSO BE FARTHER SOUTH...PERHAPS CLOSE ENOUGH TO CLIP THE
NORTHWEST PART OF OUR CWA. NOT ENOUGH CONFIDENCE TO PUT ANY POPS
IN THE FORECAST ON SATURDAY FOR POST FRONTAL PRECIP...BUT BELIEVE
THE GFS FORECAST IS MUCH TOO WARM WITH TEMPS SINCE IT DOES TAP
INTO A GOOD PIECE OF ARCTIC AIR ACROSS NW CANADA. HAVE KEPT OUR
PREVIOUS FORECAST OF TEMPS THIS WEEKEND IN TACT...WHICH IS
SIGNIFICANTLY COLDER THAN LATEST GFS/MEX NUMBERS.



San Angelo...

EXTENDED FORECAST CONTINUES TO BE PROBLEMATIC. WEAK TROUGH PASSES
ACROSS TEXAS ON TUESDAY AND TUESDAY NIGHT...AND WILL COMBINE WITH
BETTER MOISTURE TO PRODUCE SHOWERS SPREADING NORTHWARD ACROSS THE
AREA. BEST CHANCES CERTAINLY ACROSS THE EAST WILL CONTINUE THE
HIGH CHANCE POPS ALREADY IN PLACE.

MODELS IN DISAGREEMENT OVER THE SITUATION FOR NEXT WEEK...AND WITH
THE MODELS SHOWING LITTLE RUN TO RUN CONSISTENCY...FORECAST IS A
LOW CONFIDENCE ONE. GFS DROPS A DEEP TROUGH INTO THE SOUTHERN
ROCKIES...THEN SHIFT MOST OF THIS ENERGY WELL TO THE NORTH BY
FRIDAY NIGHT. THIS PRODUCES A COOLER BUT DRY PATTERN FOR WEST
CENTRAL TEXAS . ON THE OTHER HAND...THE ECMWF KEEPS MUCH MORE OF
THIS ENERGY MUCH FARTHER SOUTH...WITH ANOTHER CLOSED LOW MOVING
ALONG THE RED RIVER VALLEY ON SATURDAY. THIS PRODUCES A MUCH
COLDER AND WETTER PATTERN...WITH EVEN A CHANCE OF WINTRY
PRECIPITATION FOR THE AREA. GUT FEELING IS THAT...AFTER THE
SUCCESS OF THE ECMWF WITH THE SYSTEM LAST WEEK...THAT THE ECMWF
MAY END UP CLOSER TO REALITY. BUT GIVEN THE EXTENDED RANGE AND
CONSISTENCY ISSUES...WILL OPT FOR A MORE MIDDLE OF THE ROAD
SOLUTION FOR NOW. COOLER AND ADDED A CHANCE OF RAIN.



Norman, OK...

MODEL SOLUTIONS DIVERGE FOR THE LATTER PART OF THE FORECAST WITH
RESPECT TO THE UPPER SYSTEM LIFTING FROM THE SOUTHERN ROCKIES INTO
THE PLAINS. ECMWF AND GFS HAVE BASICALLY FLIP FLOPPED THEIR
SOLUTIONS FROM THIS TIME YESTERDAY WITH THE ECMWF NOW HOLDING BACK
MORE ENERGY IN THE BASE OF THE TROUGH AND EJECTING A SECONDARY LOW
ACROSS THE AREA ON SATURDAY WHILE THE GFS KEEPS THE MAIN FOCUS ON
THE INITIAL LOW LIFTING INTO THE NRN PLAINS. WHILE BOTH SOLUTIONS
DRIVE A COLD FRONT THROUGH THE AREA FRIDAY/FRIDAY NIGHT WITH COOLER
TEMPS INTO THE WEEKEND...THE GFS WOULD END MOST OF THE PRECIP BY FRIDAY
NIGHT WHILE THE ECMWF WOULD KEEP A THREAT OF PRECIP WELL INTO
SATURDAY. GIVEN THE LARGE DIFFERENCES WILL NOT MAKE ANY BIG CHANGES
TO CURRENT GRIDS WHICH KEEP SOME LOW POPS INTO SATURDAY FOR PARTS OF
THE AREA.

[Paul]

I think the hard freeze warning hould have been exteneded over all of Harris and Brazoria County. Sitting at 33F in Pearland rigth now at 11pm.....NWS forecast of 31F is in big time jeopardy here. I would be willing to bet I get into the upper 20s tonight.

[Paul]

Good site to see local temps though I think some of these need to be calibrated.

http://www.wunderground.com/wundermap/? ... &wmo=99999

0z GFS something interesting on day 3

http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_066l.gif

after that nada to get excited about....

Is it tropical cyclone season yet?....

[srainhoutx]

Another hard freeze this morning in SE TX with 26 for 5 hours so far in NW Harris County. Things look to get interesting Tuesday through Thursday for Central and Eastern TX with a robust short wave approaching and bringing some high percentage rain chances. The QPF totals are very encouraging and a chance at some strong storms/MCS as well. HGX is mentioning the possibility of heavy rainfall and hail. We certainly have shifted from our boring weather pattern of the past couple of months toward a more active period.



HPC:

SRN STREAM SHRTWV ENERGY ADVANCING EWD OUT INTO THE SRN PLAINS ON
TUE WILL BE INTERACTING WITH AN INCREASING SRLY RETURN FLOW OF
MOISTURE FROM THE GULF OF MEXICO BY LATER IN THE DAY AND THROUGH
EARLY WED. THE RESULT SHOULD BE THE DEVELOPMENT AND EXPANSION OF
AN AREA OF SHWRS/TSTMS ACRS CNTRL/ERN TX AND INTO MUCH OF THE LWR
MS VLY. THE GUIDANCE HAS TRENDED A LITTLE MORE ROBUST OVER THE
LAST DAY OR SO WITH THE MID LVL FORCING/DYNAMICS AND THIS SHOULD
HELP YIELD A STRONGER EVOLUTION OF CONVECTION WITH THE EXPECTATION
OF A MORE CONCENTRATED/ORGANIZED BAND OF CONVECTION MOVING EWD
ACRS THE WRN GULF COAST ON WED WITH HVY RAINFALL AMTS. THE
ECMWF/GFS SOLNS ARE DEPICTING A WELL-DEFINED LOW LVL JET OF UP TO
40 KTS AND A POOL OF 1.25 TO 1.5 INCH PWATS CROSSING FAR SERN
TX/LA AND COINCIDING WITH THE ARRIVAL OF THE UPR LVL SUPPORT.
EXPECT A FAVORABLE THERMODYNAMIC ENVIRONMENT FOR THE CONVECTION
AND WHAT WILL LIKELY QUALIFY AS AN MCS. THE ENERGY/CONVECTION
THOUGH SHOULD MOVE EWD WED NIGHT/THU TWD THE CNTRL GULF
COAST...AND IT IS EXPECTED TO WEAKEN WITH TIME AS IT ENCOUNTERS A
MORE STABLE BNDRY LYR. THE UPR LVL SUPPORT SHOULD ALSO BE
GRADUALLY SHEARING OUT/WEAKENING. HPC PREFERRED A SOLN TWD THE
WETTER GFS/ECMWF SOLNS...WITH THE HEAVIER AMTS ADJUSTED CLOSER TO
THE GULF COAST.



DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1246 AM CST MON DEC 27 2010

VALID 281200Z - 291200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
A RELATIVELY LOW AMPLITUDE/PROGRESSIVE/SPLIT LARGE SCALE UPPER FLOW
REGIME IS EXPECTED TO BE PREVALENT OVER THE CONUS BY TUESDAY.
SEVERAL LOW AMPLITUDE SHORTWAVE TROUGHS ARE EXPECTED TO CROSS THE
SOUTHERN TIER OF THE CONUS...WITH TSTM POTENTIAL INCREASING TUESDAY
NIGHT ACROSS EAST TX/ARKLATEX. ADDITIONALLY...NEAR-COASTAL/OFFSHORE
TSTMS WILL BE POSSIBLE ACROSS THE PACIFIC NORTHWEST TUESDAY
NIGHT/EARLY WEDNESDAY AS AN UPPER TROUGH DEEPENS ALONG THE NORTHWEST
COAST.

...SOUTHEAST/EAST-CENTRAL TX TUESDAY NIGHT...
IN TANDEM WITH A PROGGED SOUTHERN STREAM SHORTWAVE TROUGH...LARGE
SCALE HEIGHT FALLS/WARM ADVECTION SHOULD CONTRIBUTE TO
GRADUAL/MODIFIED MOISTURE RETURN AND INCREASING TSTM POTENTIAL
TUESDAY NIGHT/EARLY WEDNESDAY ACROSS SOUTHEAST TX TO THE ARKLATEX.
GIVEN THE RECENT FRONTAL INTRUSION ACROSS THE GULF/CARIBBEAN AND
CURRENTLY OBSERVED TRAJECTORIES...QUALITY MOISTURE RETURN IS
UNLIKELY AND A RELATIVELY LIMITED BUOYANCY ENVIRONMENT IS PROBABLE
THROUGH THE END OF THE PERIOD. ACCORDINGLY...MUCH OF THE CONVECTION
INLAND TUESDAY NIGHT COULD REMAIN ELEVATED ABOVE A MARGINALLY
MOIST/BUOYANT NEAR-SURFACE LAYER. WHILE FAVORABLE WIND FIELDS
COMBINED WITH INCREASING BUT MODEST MOISTURE COULD PERHAPS SUPPORT A
FEW STRONG/POSSIBLY ROTATING STORMS TUESDAY NIGHT/EARLY
WEDNESDAY...THE OVERALL SEVERE POTENTIAL APPEARS LOW SUCH THAT
PROBABILITIES ARE NOT CURRENTLY WARRANTED.

..GUYER.. 12/27/2010

[wxman57]

No freeze at my house this morning.

[biggerbyte]

Many hours below freezing here last night. It was 30 before midnight. At some point this cold weather has to meet up with our new found rain chances. January or February, if we don't warm up, could be interesting.

[srainhoutx]

The 12Z NAM continues to advertise a wet/stormy pattern in the Tuesday/Wednesday time frame. Infact the NAM suggests a rather strong vort max (upper level energy) swinging through near the Wednesday 12Z time frame with a possible MCS (Meso Convective System) near the Middle/Upper TX Coast. Certainly some interesting weather to be mindful of as we head toward the New Year.

[redneckweather]

I'm guessing the New Year's Eve storm system is off the table now?

[srainhoutx]

Not yet redneckweather. The models are flip flopping with the Pacific energy and just how many Upper Lows there will infact be. Last nights 00Z runs were drier via the GFS for our area and a double Upper Low with the Euro and Canadian were much 'wetter'. The 'issues' will likely change several times during the week as guidance struggles with the energy from the SJT and tropical forcing across the Central Pacific as well as Northern stream energy diving into the Intermountain West. If the second low is real and deeper into the SW as the Euro/Canadian suggest, there will be more dialog from the NWS offices in the days ahead. Regarding the next cold front Friday/Saturday, it is Arctic in nature.

[srainhoutx]

12Z GFS 60 hour precip totals...

[redneckweather]

Thanks Srain. I do plan on getting into some snow with this one if chances are good up around the Red River so any info on this would be great.

[srainhoutx]

Thanks Srain. I do plan on getting into some snow with this one if chances are good up around the Red River so any info on this would be great.

Will do redneckweather. FYI: The 12Z GFS says not likely for this weekend. Let's see what the other models suggest. To be honest, I'm not hugging any model at this range with such a dynamic setup. The Winter storm this past weekend did not become clear for our East Coast neighbors until around 36-48 hours out, for what it's worth.

[sambucol]

Regarding the next cold front Friday/Saturday, it is Arctic in nature.

What kind of high and low temps will we have here?

[redneckweather]

I'm seeing that the latest GFS is drying things out rather quickly with the New Year's Eve storm system but the Ensembles are keeping energy back after the frontal passage.

I'm looking at a target area north of the Red about an hour or so..inbetween Tulsa and the Red IF things start to trend in my favor. I don't have the wife quite on board because of the waffling around with models. She won't hit the road unless snow chances are good and more realistic. lol

I'm looknig forward to the stormy weather over the next couple of days. That will be HUGE change.

[srainhoutx]

The GFS Ensembles do look encouraging and the GGEM (Canadian) some what agrees with a chance at wintry precip in OK...

[svrwx0503]

I'm guessing the New Year's Eve storm system is off the table now?

Like srain said, it is not quite off the table just yet as the 12z GFS does still show a deep trough across the central Rockies back into the southwest US, but not nearly as deep as the 12z run this past Saturday. As a result, 850-700mb winds are more from the southwest which will tend to do two things...one, help strengthen our pesky low level capping inversion by bringing warmer/drier air in just above the surface from Mexico, as well as possibly shunt the best moisture off to the northeast like we have seen many times down here. What is needed for us to get a good genuine severe weather event is for 850mb winds to be out of the south or even a little east of south which is much more likely to occur with a deeper (digging down into northern Mexico), negatively tilted trough located back to our west. Unfortunately this is not indicated by this morning model runs. Best bet with the current progs is for some scattered showers developing along the front with some isolated thunder up north. The good news is that long range models continue to indicate more of an unsettled pattern sticking around through the first week of 2011.

[srainhoutx]

HPC says the GFS is probably too progressive regarding the New Years Weekend event...and caution is needed regarding the second low as there is still considerable spread in the ensembles...


EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
218 PM EST MON DEC 27 2010

VALID 12Z THU DEC 30 2010 - 12Z MON JAN 03 2011

...SNOWSTORM MOVING FROM THE ROCKIES TO THE UPPER MIDWEST
THU-SAT...
...HEAVY RAIN POSSIBLE MS-TN RIVER VALLEYS/CENTRAL GULF COAST
SAT-SUN...

12Z GUIDANCE IS NEARLY IDENTICAL TO OTHER RECENT GUIDANCE
CONCERNING THE LONGWAVE FLOW EXPECTED TO INFLUENCE THE CONUS IN
THE MEDIUM RANGE PERIOD...WITH A SLOW MOVING CUT-OFF LOW
PROGRESSING FROM THE ROCKIES TO THE UPPER MIDWEST DAYS 3-5...WHILE
AN INTENSE POLAR JET SPLITS OVER THE EASTERN PACIFIC DUE TO
BLOCKED DOWNSTREAM FLOW AND PRODUCES A SMALLER BUT PERHAPS STILL
SIGNIFICANT CUT-OFF LOW ALONG THE WEST COAST BY DAYS 5/6.

THE MAIN DIFFERENCES NOTICED WITH THE BULK OF 12Z GUIDANCE IS FOR
SLOWER PROGRESSION OF THE LARGE CUT-OFF AS IT REACHES THE UPPER
MIDWEST FRIDAY NIGHT/SATURDAY...ALONG WITH SLIGHTLY BETTER PHASE
AGREEMENT WITH A 2ND SMALLER LOW NEARING CALIFORNIA SATURDAY
NIGHT/SUNDAY. THUS...HAVE BLENDED ABOUT 25 PERCENT EACH OF THE 12Z
CANADIAN/UKMET WITH THE EARLY MORNING BLEND...WHICH CONSISTED OF
THE 00Z GFS/ECMWF AND 00Z ECMWF ENSEMBLE MEAN...TO CONSTRUCT THE
FINAL PRESSURE/FRONT PROGS.

THE FINAL CHANGES WILL EMPHASIZE A SIGNIFICANT SNOWSTORM
DEVELOPING ACROSS MUCH OF THE ROCKIES ON THURSDAY BEFORE ENTERING
THE CENTRAL/NORTHERN PLAINS...WITH BLIZZARD CONDITIONS POSSIBLE
ACROSS PARTS OF THE DAKOTAS/MINNESOTA FRIDAY/SATURDAY.
MEANWHILE... THE LARGE AND EXPANDED TEMPERATURE GRADIENT THAT
ACCOMPANIES MOVEMENT OF THE LOW INTO THE PLAINS SHOULD ALLOW FOR
MUCH MILDER AND WINDY CONDITIONS TO SPREAD FROM THE MISSISSIPPI
VALLEY EASTWARD THROUGH THE REMAINDER OF THE PERIOD...WITH HEAVY
RAIN LIKELY FORMING ACROSS PORTIONS OF THE MS-TN RIVER
VALLEYS/GULF COAST SAT-SUN AS A COLD FRONT MOVES THROUGH.
FINALLY...ASIDE FROM THE 12Z GFS WHICH CONTINUES TO LIE NEAR THE
FASTER EDGE OF THE DETERMINISTIC GUIDANCE...OTHER GUIDANCE
INCLUDING THE 12Z UKMET/CANADIAN SHOW IMPROVED CLUSTERING
REGARDING ANOTHER CUT-OFF LOW DRIFTING SOUTHWARD AND VERY CLOSE TO
THE CALIFORNIA COAST SAT-MON. HOWEVER...ENSEMBLE SPREAD IS MUCH
LARGER...WHICH WARRANTS CAUTION IN RELYING TO0 MUCH ON ANY ONE
SOLUTION FOR SUCH A SMALL SYSTEM WHICH THE MODELS ARE LIKELY
HAVING DIFFICULTY RESOLVING.

JAMES

[srainhoutx]

For redneckweather via Tulsa this afternoon...

A MAJOR CHANGE IN THE WEATHER PATTERN WILL TAKE PLACE FRIDAY AS A
SHARP COLD FRONT SWEEPS ACROSS THE SOUTHERN PLAINS. THERE IS
PRECIPITATION IN THE FORECAST ASSOCIATED WITH FRONTAL PASSAGE.
MOISTURE AND INSTABILITY APPEAR TO SUPPORT THUNDERSTORMS AHEAD OF...
AND ACCOMPANYING THE FRONT. TEMPERATURES WILL COOL RAPIDLY BEHIND
THE FRONT... WITH ANY REMAINING PRECIPITATION TURNING WINTRY.

SO FAR... MODELS HAVE BEEN WISHY-WASHY AND FLIP-FLOPPING WITH
REGARD TO POST FRONTAL PRECIPITATION... WITH THE LATEST RUNS
COMING IN MOSTLY DRY. THE PREPONDERANCE OF INFORMATION AVAILABLE
AT THIS TIME POINTS TO SMALLER PRECIPITATION CHANCES AND LIGHT
AMOUNTS. HAVE THEREFORE BACKED OFF SOME ON POPS FOR FRIDAY NIGHT
THROUGH SATURDAY... WITH THE GREATEST CHANCES BEING TOWARD THE
SOUTH EAST. THERE COULD BE SMALL ACCUMULATIONS WITH ANY
PRECIPITATION THAT DOES FALL... BUT IMPACTS SHOULD NOT BE
SIGNIFICANT. HOWEVER... GIVEN MODEL PERFORMANCE AND RELIABILITY
WITH THIS SYSTEM THUS FAR... AND GIVEN SEASONAL VOLATILITY...
TOMORROW MAY PAINT A DIFFERENT PICTURE. AS WAS SAID IN EARLIER
DISCUSSIONS... STAY TUNED.