December: New Years Eve Outlook

[srainhoutx]

^^
To put it bluntly...there is way to much emphasis on what the numerical guidance output suggests versus actual forecasting the pattern and what is seen upstream and is actual ground truth. Remember we went through this two weeks ago and many played catch up as the event got closer. I believe that this go around will last longer and be much more of a challenge from a forecasting stand point. That said this 1058+ Arctic air mass has teeth and is stronger than the last air mass was. Stay Tuned. I suspect a lot changes will be forthcoming over the next 3 to 6 days.

[djmike]

^^
To put it bluntly...there is way to much emphasis on what the numerical guidance output suggests versus actual forecasting the pattern and what is seen upstream and is actual ground truth. Remember we went through this two weeks ago and many played catch up as the event got closer. I believe that this go around will last longer and be much more of a challenge from a forecasting stand point. That said this 1058+ Arctic air mass has teeth and is stronger than the last air mass was. Stay Tuned. I suspect a lot changes will be forthcoming over the next 3 to 6 days.

***
Thanks Srain! I dont mean to be a scrooge about it, I just found it frustrating that every 7 day I see or read is far from what I read on here. I know many mets like to play it safe and take the "wait and see approach". I look forward to the possible changes over the next 3-6 days!

[srainhoutx]

Morning Update from Jeff:

Extended period of cold weather and winter precipitation likely over a large part of TX over the next 7 days.

Arctic air mass has invaded from Canada in the last 24 hours and heading south.

Arctic boundary currently over the TX panhandle and moving southward. Upstream air temperatures range from -1 in northern Montana to 7 at Denver and 30 just past the front at Amarillo compared to a “hot” and steamy 71 at Houston. Boundary will slice southward today likely at a faster pace than most guidance is suggesting as is usually the case with such cold shallow air masses. SE TX will remain in the warm sector today as southerly winds continue to pump low level moisture into the region ahead of the strong cold front. Dewpoints are exceeding local near shore water temperatures resulting in dense sea fog along the coast and this will continue periodically until the cold front pushes off the coast. Highs will again push into the 80’s today just short of records for the 4th.

Thursday:

Arctic boundary arrives into SE TX. Models are in decent agreement on the frontal timing and have the front very near College Station around sunrise and near Houston by 300-600pm. This will play havoc with forecasted high temperatures on Thursday as highs will be pre front and lows will be post front. A good part of the area may reach 75-80 degrees before the bottom falls out by Thursday afternoon/evening. Post frontal temperatures will fall quickly into the 50’s and then 40’s with gusty north winds. Expect a chance of showers and possibly a thunderstorm along the frontal boundary, but widespread heavy rainfall is not expected nor severe weather.

Thursday night-Friday evening:

Arctic high builds into the area with the slow moving front pushing offshore. Temperatures will be falling through the entire period from the 50’s into the 40’s by Friday morning and the 30’s during the day on Friday under strong N winds, clouds, and rain. Forecast soundings show a shallow cold air mass only about 1000 ft thick above the surface with a significant warm nose atop the surface cold dome up to around 12,000 ft. Moisture will overrun the shallow cold dome keeping clouds and rainfall going into Friday making it a miserably cold, wet, and windy day. Could see a few locations fall to near freezing during the day on Friday from north of College Station to north of Huntsville, but do not expect any icing impacts during the day Friday. NAM shows College Station very near freezing by 600am Friday morning, but this model is running about 1-2 degrees colder than the GFS model.

Friday night-Saturday:

Cold air continues to draw down into the region from what will be an ice covered north TX by this point. Will likely see the freezing line penetrate our region during the evening hours Friday and slowly drop southward overnight. GFS sounding for CLL shows the temperature falling to below freezing between 600pm and midnight on Friday, but not at Conroe. Think the surface freezing line will be somewhere along or near a Brenham to north of Conroe to Livingston line Saturday morning. Main jet dynamics shift eastward late Friday and suspect a decrease in rain chances Friday night. Given the continued overrunning pattern in place, very light rain or drizzle could continue much of the night. Sounding profiles in the sub-freezing area show a large warm nose continues above the surface…so this would be a freezing drizzle set up. Could see some light accumulations of ice from Friday evening to mid-morning Saturday north of a Brenham to Conroe to Livingston Line. All areas south of this line will remain just warm enough to keep anything that falls in the liquid form. Highs Saturday will range from the mid 30’s north to near 40 along the coast with continued N winds.

Saturday night-Sunday:

Jet streak moves into the region late on Saturday helping to enhance lift and increase precipitation. Not sure our northern counties will get much above freezing on Saturday so once again the threat for freezing rain enters the picture for Saturday night into Sunday morning. Could see a little bit more of the area drop to below freezing Saturday evening with the freezing line possibly from north of Columbus to Hempstead to Conroe to Livingston. Profiles continue to show a good warm nose so the P-type would be freezing rain if the surface is sub-freezing. Could again see some ice accumulations across our northern counties during this period especially on elevated surface such as tree limbs and power lines. By this point the air temperatures would have also cooled elevated bridges and overpasses to near the freezing point so some ice on those surface could be possible by Sunday morning. Pretty hard this far out to determine where the freezing line will end up and how much precipitation may fall. Highs on Sunday will range from the mid to upper 30’s north to the mid 40’s along the coast.

Sunday night-Monday:

Secondary surge of very cold arctic air arrives around Monday helping to prolong this cold spell. GFS has been flipping all around with the amount of cold air that dumps southward with some runs showing bitter cold with lows well into the 20’s across the area by the middle of next week and others showing lows in the 30’s. ECMWF model yesterday agreed with the colder GFS solutions showing 1’s as far south as N TX by the middle of next week. Teleconnections continue to favor arctic air dumps into the US for the next 5-10 days.

It is very possible that some locations across our area will fall below 50 degrees on Thursday and not rise above 50 again until sometime mid to late next week.

Note:

Winter Storm Watches have been issued for a large part of N TX for the accumulation of ice from freezing rain. This will be a prolonged winter weather event with ice accumulation likely from late Thursday through Monday of next week….possibly longer. Travel N of SE TX this weekend will be extremely hazardous and continued ice accumulations on trees and power lines may result in widespread power outages across portions of N TX.

As with any winter weather threat this far south the uncertainty is large and the forecast will be changing over the next few days.

[srainhoutx]

This is the latest HPC/WPC Winter Weather Update as of this morning for any potential icing issues valid 00Z Saturday or Friday afternoon/evening local time.

[srainhoutx]

Here are the latest surface observations as of 14Z. Note the cold air has indeed arrived across the Plains extending W into Colorado and is pushing S through the Panhandles of Texas and Oklahoma. It is noteworthy via water vapor imagery that a series of upper air disturbances are dropping S as the ride up and over the EPO Ridge near the Aleutian Islands of Alaska. These disturbances will continue to drop S into Arizona and Northern Mexico before turning ENE and crossing Texas/Oklahoma/Arkansas and the Northern half of Louisiana. Also notice the sub tropical jet connection that is becoming increasingly noisy SW of Southern California into the Baja of Mexico's East Pacific Coast. That moisture will likely become embedded with each upper air disturbance as they drop S allowing for over running light drizzle/light rain to develop into the weekend.

12042013 14Z_metars_ict.gif

[srainhoutx]

Winter Storm Warning hoisted basically from Oklahoma City Metro S to Wichita Falls, TX and on E.

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE NORMAN OK
942 AM CST WED DEC 4 2013

OKZ016>020-022>048-050>052-TXZ083>090-042345-
/O.UPG.KOUN.WS.A.0003.131205T1200Z-131207T0000Z/
/O.NEW.KOUN.WS.W.0005.131205T1200Z-131207T0000Z/
CUSTER-BLAINE-KINGFISHER-LOGAN-PAYNE-WASHITA-CADDO-CANADIAN-
OKLAHOMA-LINCOLN-GRADY-MCCLAIN-CLEVELAND-POTTAWATOMIE-SEMINOLE-
HUGHES-HARMON-GREER-KIOWA-JACKSON-TILLMAN-COMANCHE-STEPHENS-
GARVIN-MURRAY-PONTOTOC-COAL-COTTON-JEFFERSON-CARTER-JOHNSTON-
ATOKA-LOVE-MARSHALL-BRYAN-HARDEMAN-FOARD-WILBARGER-WICHITA-KNOX-
BAYLOR-ARCHER-CLAY-
INCLUDING THE CITIES OF...WEATHERFORD...CLINTON...WATONGA...
KINGFISHER...GUTHRIE...STILLWATER...CORDELL...ANADARKO...YUKON...
EL RENO...MUSTANG...OKLAHOMA CITY...CHANDLER...CHICKASHA...
PURCELL...NORMAN...MOORE...SHAWNEE...SEMINOLE...HOLDENVILLE...
HOLLIS...MANGUM...HOBART...ALTUS...FREDERICK...LAWTON...DUNCAN...
PAULS VALLEY...SULPHUR...ADA...COALGATE...WALTERS...WAURIKA...
ARDMORE...TISHOMINGO...ATOKA...MARIETTA...MADILL...DURANT...
QUANAH...CHILLICOTHE...CROWELL...VERNON...WICHITA FALLS...
MUNDAY...KNOX CITY...SEYMOUR...ARCHER CITY...HOLLIDAY...
LAKESIDE CITY...HENRIETTA
942 AM CST WED DEC 4 2013

...WINTER STORM WARNING IN EFFECT FROM 6 AM THURSDAY TO 6 PM CST
FRIDAY...

THE NATIONAL WEATHER SERVICE IN NORMAN HAS ISSUED A WINTER STORM
WARNING FOR ACCUMULATIONS OF SNOW...SLEET...AND FREEZING RAIN...WHICH
IS IN EFFECT FROM 6 AM THURSDAY TO 6 PM CST FRIDAY.

* THURSDAY...6 AM TO 6 PM: LIGHT FREEZING RAIN.

* THURSDAY NIGHT THROUGH FRIDAY: ANOTHER ROUND OF HEAVIER WINTER
PRECIPITATION IS EXPECTED.

* FOR AREAS ALONG AND SOUTHEAST OF A HOLDENVILLE...TO ADA...TO
ARDMORE OKLAHOMA AND WICHITA FALLS TEXAS...MAINLY FREEZING RAIN
AND SOME SLEET.

* MAIN IMPACT: ICE ACCUMULATIONS UP TO 1/2 INCH MAY CAUSE POWER
OUTAGES AND HAZARDOUS TRAVEL CONDITIONS...ESPECIALLY ON BRIDGES
AND OVERPASSES.

* FOR AREAS NORTH AND WEST OF HOLDENVILLE...TO ADA...TO ARDMORE
OKLAHOMA AND WICHITA FALLS TEXAS...INCLUDING LAWTON AND
OKLAHOMA CITY. SOME LIGHT FREEZING RAIN WILL BE POSSIBLE WITH
SNOW AND SLEET AS THE MAIN PRECIPITATION.

* MAIN IMPACT: SNOW AND SLEET ACCUMULATIONS OF 3 TO 6 INCHES WITH
LOCALLY HIGHER AMOUNTS POSSIBLE. THIS WILL LIKELY MAKE TRAVEL
CONDITIONS HAZARDOUS.

* OTHER IMPACTS: VERY COLD WIND CHILLS FROM NEAR ZERO TO THE LOWER
TEENS WILL BE POSSIBLE...ESPECIALLY FRIDAY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

AVOID TRAVEL. BE SURE YOU CAN TAKE CARE OF YOURSELF AND YOUR
FAMILY IF YOU LOSE ELECTRICAL POWER. MONITOR WEATHER FORECASTS
AND INFORMATION.

[Portastorm]

Well, for portions of south central Texas, both the 12z NAM and 12z GFS are coming in a little colder and include a little more precip than 0z runs for this weekend.

[wxman57]

New GFS meteogram for Houston (IAH). Cold, miserable, rainy weekend - then the weather turns colder!. No ice:

[srainhoutx]

The 12Z GEFS (Ensemble Mean) suggest very chilly air, some potential for precip as the previously mentioned short wave does cross our Region and a 500mb Anomaly pattern is suggesting early/mid next week could definitely be nasty, if that ensemble guidance is correct.

12042013 12Z GEFS gfs-ens_T2ma_namer_25.png

12042013 12Z GEFS gfs-ens_apcpn24_namer_24.png

12042013 12Z GEFS gfs-ens_z500a_namer_25.png

[MontgomeryCoWx]

MCFARLAND SIGGY!

[don]

I think we'll probably just get a very cold rain this weekend with maybe areas such as Huntsville and College station getting freezing rain with light icing probably primarily on elevated surfaces. I think we may have a better opportunity of getting something frozen during the later half of next week when we'll have deeper cold air established across the area, as a disturbance pushes through from the west. The strength of the disturbance may ultimately be what determines if we see anything frozen or not. Notice how the 6z run of the GFS is more aggressive with the disturbance (which results in a large swath of mix precipitation across Southeast Texas) while the 12z has backed off with a weaker disturbance that barely manages to produce moisture. FWIW the 12z Canadian is also more on the aggressive side showing a large swath of wintry precip also across the area similar to the 6z GFS.

6z



12z

[srainhoutx]

Remember the Euro has a bit of a warm bias, but temps in the single digits across the Panhandle and N Texas may well be possible next Tuesday into Wednesday. Also note the next surge of Arctic air dropping S from Canada. Those 2 meter temps up in the Northern Plains are very close to -30 F.

[srainhoutx]

Expect some changes from the HPC/WPC Winter Weather Outlook for Central and SE Texas regarding some potential icing issues further S for Friday night into Saturday.

[wxman57]

MCFARLAND SIGGY!

Now you must find the PDF from the retired NWS BRO met who first wrote on the signal for Arctic outbreaks to South Texas.

http://www.srh.noaa.gov/ssd/techmemo/tm88.htm

[srainhoutx]

HPC/WPC Forecaster Kocin is at the forecast desk this afternoon and he has updated the icing potential and as we can see, the chances have increased for portions of Central and SE Texas.

[Portastorm]

EWX has just issued its afternoon forecast discussion and continues somewhat unimpressed by the coming event but has some words of caution in its AFD.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
327 PM CST WED DEC 4 2013

.SHORT TERM (TONIGHT THROUGH THURSDAY NIGHT)...
ABOVE NORMAL TEMPERATURES WILL CONTINUE THIS EVENING WITH LOW
CLOUDS AND PATCHY FOG DEVELOPING LATE TONIGHT. THE STRONG ARCTIC
FRONT IS SET TO ENTER THE FORECAST AREA BY AROUND 09Z AND INTO
AUSTIN BY 12Z AND SAT BY 15Z. MODEL RUN-TO-RUN TRENDS SUGGEST A
SLIGHT ACCELERATION OF THE FRONT POSSIBLE. DAYTIME TEMPERATURE
TRENDS CONTINUE DOWNWARD FOR THURSDAY...AND BY LATE EVENING...A FEW
LOCATIONS OF THE NORTHERN HILL COUNTRY MAY BE AT RISK OF
REACHING THE FREEZING MARK. SIMILAR TO THE PREVIOUS ARCTIC
FRONT... LIGHT TO MODERATE RAIN SHOWERS ARE EXPECTED TO OVERRUN
THE ARCTIC AIR AND PRODUCE A THREAT OF FREEZING RAIN...ESPECIALLY
LATE THURSDAY NIGHT. PF AMOUNTS WILL BE MAINLY BELOW 1/10 INCH...
AND SO A WINTER STORM WATCH IS NOT ANTICIPATED AT THIS TIME. A
WINTER WEATHER ADVISORY LEVEL THREAT IS CURRENTLY ANTICIPATED...
WITH WARM GROUND TEMPERATURES EXPECTED TO CONFINE EARLY ICING TO
MAINLY BRIDGES AND OVERPASSES.

&&

.LONG TERM (FRIDAY THROUGH WEDNESDAY)...
PRECIPITATION RATES ARE EXPECTED TO DECREASE FRIDAY AS A SHALLOW
SHORTWAVE TROUGH PASSES MAINLY NORTH OF THE AREA. ISENTROPIC LIFT
OVER THE FRONT IS EXPECTED TO CONTINUE THROUGH THE WEEKEND...BUT
WILL HAVE TO OVERCOME CONTINUED DRY AIR REINFORCEMENT IN THE
LOWEST 3000 FT OR MORE. LIGHT RAIN AND SPRINKLES WILL EVENTUALLY
BE REDUCED TO DRIZZLE AT THE SURFACE...SO VERY LITTLE ICING IS
ANTICIPATED...DESPITE SEVERAL HOURS OF OPPORTUNITY OF FREEZING
DRIZZLE AND SLEET SHOWN IN THE FORECAST. PERSISTENT EVAPORATIVE
COOLING FROM THE LIGHT PRECIPITATION PATTERN AND MODEL TRENDS ON
TEMPERATURES SUGGEST THIS AIR MASS WILL BE COLDER THAN THE ONE
PRIOR TO THANKSGIVING. IF ANY SHORTWAVE ACTIVITY IS DETECTED IN
THE BROAD ZONAL FLOW ALOFT...THE HIGHER PRECIPITATION RATES THAT
RESULT WOULD WARRANT A WINTER STORM WATCH OR WARNING TO BE
ISSUED.

BY LATE SUNDAY MORNING...A MORE SIGNIFICANT SHORTWAVES IN
THE FLOW ALOFT IS EXPECTED TO PASS NORTH OF SOUTH CENTRAL TEXAS.
AS IT DOES SO...THERE IS A GOOD CHANCE FOR WAKE SUBSIDENCE TO
CLEAR OUT SKIES AND MODIFY THE TEMPERATURES TO END THE FREEZING
PRECIPITATION POTENTIAL. MODEL TRENDS...ESPECIALLY FROM THE
GFS...SHOW THE BASE OF THE BROADER UPPER TROUGH BECOMING MORE
SHALLOW SUNDAY INTO MONDAY...THUS FURTHER INCREASING THE CHANCE
FOR CLEARING SKIES. NEVERTHELESS...COLD AIR ADVECTION WILL BE
FURTHER REINFORCED ON MONDAY WITH THE COLDEST MORNING LOWS OF THE
SEASON EXPECTED OVER MANY AREAS BY TUESDAY MORNING. A SPLIT FLOW
PATTERN REMAINS IN THE FORECAST FOR THE REST OF NEXT WEEK...
LEADING TO A HIGHER CHANCE FOR CLOUD COVER AND COOLER THAN
NORMAL TEMPERATURES CONTINUING INTO NEXT WEEKEND.

[cperk]

HPC/WPC Forecaster Kocin is at the forecast desk this afternoon and he has updated the icing potential and as we can see, the chances have increased for portions of Central and SE Texas.

That's quite a bit further south.

[djmike]

/\/\/\

...and east!

[snowman65]

Sure hope all the ice stays up north. Wife and I are planning on shopping alot Saturday in the Beaumont area....

[cperk]

Sure hope all the ice stays up north. Wife and I are planning on shopping alot Saturday in the Beaumont area....

Cold and shopping goes well,but cold and ice and shopping,not so well.