NOVEMBER: Warming Up To End The Month

[Portastorm]

Excellent synopsis, sir. Promises to be a fascinating weather weekend. And damn cold!

[srainhoutx]

Morning Update from Jeff:

Major winter storm heading for TX with widespread impacts Sunday-Tuesday.

Will attempt to break down the multiple impacts of the incoming winter weather event by time period and location.

Today-midday Sunday:

Shallow cold arctic dome is in firm place across the state this morning, but it being overrun by a large layer of warm moist air around the 900mb level. This is resulting in widespread low clouds/fog/drizzle/light rain across the region while surface temperatures hover in the low to mid 40’s under gusty N winds across SE TX. Along and west of a line from near Del Rio to Kerrville to Abilene surface temperatures are cold enough to support light rain freezing on contact and forming into a layer of ice. TXDOT is reporting some icing of bridges and overpasses in Kerr County NW of San Antonio. Secondary surge of arctic surface high pressure currently advancing down the central plains will arrive into TX this evening (currently -5F in Fargo, ND). While there will be little to no change in the surface air temps or wind speeds, this surge will deepen the surface cold dome over the region tonight into Sunday and likely help end rain chances from NE to SW across our area tonight into midday Sunday, but also helping to set the stage for a potential mix of precipitation late Sunday.

Midday Sunday-Midday Monday:

Winter Storm moves into the state from the west.

Winter Storm Warnings have been issued from Dallas to Austin to Del Rio westward from Sunday into Monday for significant accumulations of ice and sleet. Will focus on the warning area first and then detail impacts across SE TX.

Dallas-Austin-Del Rio West (Winter Storm Warning area):

Large upper level storm system across S CA at this time will progress eastward spreading moisture and lift across the cold dome over TX. Surface temperatures Sunday morning are expected to be in the 30-36 degree range in the current warning area with a fairly pronounce warm layer above this near freezing surface layer. Onset of precipitation Sunday morning-midday into the dry low levels will help result in evaporative cooling of the air temperature toward the dewpoints which will be below freezing. Expect to see a fairly sharp temperature fall of surface temperatures to below freezing by midday in the warning area with mixed precipitation of freezing rain and sleet the common forms. Depending on which P-type is most dominant will determine accumulation amounts. Models are suggesting anywhere from .5 to 1.5 inches of liquid equivalent in the warning area which would be devastating from a freezing rain/ice stand point, but more manageable from a sleet standpoint. Given several processes in place changing the low and mid level thermal profiles in the warning area during this event, will likely not know P-type until the event is underway. Sunday night into Monday morning could see some good icing in the DFW and potentially the Austin metro areas. If the P-type is freezing rain, accumulations would likely be enough to result in downing of trees and power lines across the warning area.

SE TX:

Upper level storm system will force a coastal surface low to develop along the lower TX coast on Sunday. Gulf moisture swings northward above the cold arctic dome, but at the same time cold and dry air advection continues out of the NNE at the surface. This creates a dry sub-cloud layer and potential for wet bulb cooling across our area as the rainfall begins Sunday evening. Could see the start of the rainfall mixed with sleet over the region especially north of Houston where the low level air mass is driest. Evaporative cooling effects may be just enough to lower surface temperatures to near freezing Monday morning north of a line from Brenham to Conroe to Livingston resulting in a period of freezing rain. Ground temperatures remain very warm and do not think will be much if any accumulation even on bridges and overpasses although could see a slick spot north of a line from College Station to Huntsville. Temperatures will warm above freezing by 900-1000am Monday morning in all areas. This is a very marginal threat, but could be enough for a winter weather advisory.

Southward all rain is likely as the coastal storm moves NE along the coast. Moderate to heavy rainfall will develop in SW to NE bands along and north of the track of this surface low across much of SE TX. NE winds will increase helping to keep the cold air locked in place at the surface. Rainfall amounts of 1-2 inches are likely with isolated totals of 3-4 inches especially along the coast and possibly inland to US 59. Other impact will be increasing tides as strong ENE winds develop over the NW Gulf of Mexico in response to the deepening surface low. Could see tidal issues Monday along the Gulf facing beaches into Monday evening.

Midday Monday-Midday Tuesday:

Surface low pushes ENE across our coastal waters and east of the region by Tuesday morning taking most of the moisture with it. Upper level storm will move across TX late Monday into Tuesday with the cold pocket aloft eroding the mid level warm nose. Expect the back edge of the precipitation shield to mix with of change to snow as the thermal profiles fall below 32 through the entire column. Question at this time is how far SE this transition happens and if moisture will still be enough to produce precip. Current thinking is that across SE TX surface temperatures will still be at or above freezing and as the profile starts to become favorable for snow (removal of the warm nose) the rainfall will be ending. This is another very marginal threat and the most likely outcome at the moment is the air column will be too dry by the time the temperature is favorable for snow.

Temperatures:

Temperatures through the next 48 hours will hold in the 30’s and 40’s across the entire region. By Tuesday temperatures may break 50 degrees if a few breaks in the clouds occur late in the day. Will not see temps. break 60 until maybe Thanksgiving day.

Tuesday evening-Friday:

Storm system will be east of TX with gradually warming conditions and partly cloudy skies.

[Ptarmigan]

The possibility of freezing rain, sleet, or even snow in Houston would be a rare evemt. There has been sleet recorded in November in 1976. As for snow in November, I have never heard of that in Houstin going back to the 1880s. It could be possible that it did snow in November in Houston as some records are missing or it happened before records were kept.

[jasons2k]

I've had 2.73" the last two days. Most of it fell yesterday morning with lots of thunder & lightening.

I must say, that was the most intense "thin line of showers accompanying the front" I think I've ever seen - lol.

[srainhoutx]

Graphics are beginning to come in prior to the afternoon Winter Weather Discussion from the HPC/WPC and they are suggesting a bit more probabilities in the way of freezing rain across the Hill Country and a bit better chance of snow across the Dallas/Ft Worth Metroplex. In Lubbock, it does appear a significant snow event will develop and the projected 1040mb secondary Arctic High pressure cell should be over Oklahoma/N Texas as the storm approaches from the W. The new Coastal Low ensemble tracks from the HPC/WPC are also out.

[srainhoutx]

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
218 PM CST SAT NOV 23 2013

TXZ163-164-176>179-195>200-210>213-226-227-242030-
AUSTIN-BRAZOS-BURLESON-COLORADO-FORT BEND-GRIMES-HARRIS-HOUSTON-
LIBERTY-MADISON-MONTGOMERY-POLK-SAN JACINTO-TRINITY-WALKER-WALLER-
WASHINGTON-WHARTON-
218 PM CST SAT NOV 23 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST TEXAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

AN UPPER LEVEL DISTURBANCE WILL MOVE ACROSS CENTRAL AND EAST
TEXAS LATE SUNDAY AHEAD OF A STRONG UPPER LEVEL LOW PRESSURE
SYSTEM. A BAND OF PRECIPITATION IS EXPECTED TO DEVELOP DURING THE
EVENING AND EXPAND OVERNIGHT. TEMPERATURE AND MOISTURE PROFILES
IN THE ATMOSPHERE SUPPORT A MIX OF PRECIPITATION...RAIN/SLEET MIX
AND THEN A RAIN/FREEZING RAIN MIX NORTH OF A CALDWELL TO TRINITY
LINE LATE SUNDAY NIGHT INTO MONDAY MORNING. NO ICE ACCUMULATION
IS EXPECTED AT THIS TIME. THE PRIMARY IMPACTS WILL BE SOME MINOR
ICING ON ELEVATED SURFACES SUCH AS BRIDGES AND OVERPASSES WHERE
SOME LIGHT GLAZING MAY OCCUR. PLEASE MONITOR FOR UPDATED
FORECASTS AND THE POSSIBILITY OF A WINTER WEATHER ADVISORY.

THE STRONG UPPER LEVEL LOW PRESSURE SYSTEM IS EXPECTED TO MOVE
ACROSS THE AREA MONDAY THROUGH TUESDAY. A COASTAL LOW PRESSURE
SYSTEM IS EXPECTED TO DEVELOP IN RESPONSE TO THE UPPER LEVEL
SYSTEM. THE COMBINATION OF THE TWO WILL SUPPORT WIDE SPREAD RAIN
WITH THUNDERSTORMS OFF THE COAST. SOME RAIN BANDS MAY DEVELOP
MAINLY ON MONDAY THAT COULD PRODUCE MODERATE TO HEAVY RAIN.
RAINFALL TOTALS WILL AVERAGE BETWEEN 1 TO 2 INCHES WITH SOME
LOCALLY HIGHER AMOUNTS.

AS THE UPPER LEVEL LOW MOVES DIRECTLY OVER THE AREA ON TUESDAY...
THERE IS A SMALL CHANCE OF A MIX OF RAIN/SLEET THAT MAY OCCUR
ACROSS SOUTHEAST TEXAS. AT THIS TIME...THE BEST CHANCE FOR SLEET
WILL BE NORTH OF HIGHWAY 105.

[srainhoutx]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
330 PM CST SAT NOV 23 2013

.SHORT TERM (TONIGHT THROUGH SUNDAY NIGHT)...
SPRINKLES/LIGHT RAIN IS CURRENTLY ONLY ISOLATED IN COVERAGE THIS
AFTERNOON...BUT AN INCREASE IN ACTIVITY IS EXPECTED TONIGHT AS AN
UPPER LEVEL DISTURBANCE APPROACHES FROM THE WEST. TEMPERATURES
ACROSS THE HILL COUNTRY AND EDWARDS PLATEAU ARE CURRENTLY IN THE
MID TO UPPER 30S...BUT WILL FALL TO NEAR FREEZING TONIGHT. THE
CHANCES FOR PRECIPITATION AND COLD SURFACE TEMPERATURES WILL LEAD
TO LIGHT SLEET AND LIGHT FREEZING RAIN TONIGHT AND INTO EARLY
SUNDAY AS TEMPERATURES WILL BE SLOW TO WARM UP. DUE TO THE
POTENTIAL FOR LIGHT ICE ACCUMULATIONS...A WINTER STORM WARNING IS
IN EFFECT FOR THE HILL COUNTRY AND EDWARDS PLATEAU BEGINNING
TONIGHT. WINTRY PRECIPITATION IS NOT EXPECTED TONIGHT ACROSS THE
METRO AREAS.

THE UPPER LOW ACROSS THE SWRN U.S. WILL BEGIN TO SHIFT EASTWARD ON
SUNDAY. THIS WILL RESULT IN ANOTHER COLD AND WET DAY ACROSS SOUTH
CENTRAL TEXAS. HIGHS WILL REMAIN IN THE UPPER 30S TO LOW/MID 40S.
COLDER TEMPERATURES ARE EXPECTED SUNDAY NIGHT. MEANWHILE...CHANCES
FOR PRECIPITATION WILL REMAIN HIGH AND THEREFORE THE POTENTIAL FOR
WINTRY PRECIPITATION SUNDAY NIGHT/MONDAY MORNING WILL EXPAND
FARTHER EAST. UPGRADED THE PREVIOUS WINTER STORM WATCH TO A WINTER
STORM WARNING. THE WARNING INCLUDES THE HILL COUNTRY/EDWARDS
PLATEAU...AND ALSO THE I-35 CORRIDOR BETWEEN GEORGETOWN AND NEW
BRAUNFELS...INCLUDING THE AUSTIN METRO AREA. THE COMBINATION OF
FREEZING RAIN AND SLEET SUNDAY NIGHT INTO MONDAY MORNING WILL
CAUSE LIGHT ACCUMULATIONS OF ICE ON BRIDGES...OVERPASSES...AND
RAISED/EXPOSED SURFACES. EVEN THOUGH ICE ACCUMULATIONS ARE EXPECTED
TO BE ONE TENTH OF AN INCH OR LESS...THIS WILL NONETHELESS CAUSE
MAJOR IMPACTS FOR THE MONDAY MORNING COMMUTE.

&&

.LONG TERM (MONDAY THROUGH SATURDAY)...
THE UPPER LEVEL LOW WILL REACH NEW MEXICO/FAR WEST TEXAS ON
MONDAY AND MOVE ACROSS TEXAS ON TUESDAY. WESTERLY FLOW ALOFT WILL
ALLOW AFTERNOON TEMPERATURES ON MONDAY TO REACH THE LOW 50S ACROSS
THE RIO GRANDE PLAINS...BUT THE EASTERN HALF OF THE REGION WILL
OTHERWISE REMAIN IN THE UPPER 30S TO LOW/MID 40S. CHANCES FOR
PRECIPITATION WILL REMAIN HIGH MONDAY NIGHT INTO TUESDAY.
TEMPERATURES MONDAY NIGHT WILL AGAIN BE COLD...BUT THE ENVIRONMENTAL
PROFILE AT THAT POINT WILL BECOME MORE FAVORABLE FOR SNOW FLURRIES
TO MIX-IN WITH THE COLD RAIN ACROSS OUR NORTHERN/NORTHEASTERN
ZONES. DUE TO THE CURRENT EXPECTATION OF NO SNOW ACCUMULATIONS
AND THE ONGOING WINTER STORM WARNING...HAVE NOT ISSUED A WATCH FOR
MONDAY NIGHT/TUESDAY MORNING.
CHANCES FOR PRECIPITATION WILL END FROM WEST TO EAST ON TUESDAY AS
THE UPPER LOW MOVES EAST OF OUR AREA. THE CLOUD COVER WILL BE
SLOWER TO CLEAR OUT OF THE AREA...BUT PARTLY SUNNY SKIES ARE
EXPECTED ACROSS WESTERN PORTIONS OF THE REGION TUESDAY AFTERNOON.
SKIES WILL CONTINUE TO CLEAR THROUGH THE EVENING AND OVERNIGHT
HOURS...WITH MOSTLY SUNNY SKIES EXPECTED WEDNESDAY. AFTERNOON
TEMPERATURES WILL UNDERGO A WARMING TREND THROUGH THE END OF THE
WEEK. MODELS ARE SUGGESTING THAT RADIATIONAL COOLING WILL BE
EFFICIENT ENOUGH WEDNESDAY NIGHT TO ALLOW A WIDESPREAD FREEZE
THANKSGIVING MORNING. CLOUDS WILL BEGIN TO INCREASE THANKSGIVING
NIGHT...WHICH WILL HELP KEEP TEMPERATURES FRIDAY MORNING MOSTLY IN
THE MID 30S OR WARMER. THE WARMING TREND WILL CONTINUE INTO THE
WEEKEND...WITH HIGHS APPROACHING 70 ON SATURDAY.

[srainhoutx]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
317 PM CST SAT NOV 23 2013

.DISCUSSION...
A TIGHT PRESSURE GRADIENT IS PRODUCING STRONG WINDS ACROSS THE
CWA THIS AFTERNOON AND THIS TREND WILL LIKELY CONT OVERNIGHT.
SUSTAINED WINDS NEAR 25 MPH ARE EXPECTED ALONG THE COAST SO ISSUED
A WIND ADVISORY THROUGH 15Z SUNDAY FOR THE COASTAL TIER OF
COUNTIES. PERIODS OF LIGHT RAIN OVER THE AREA HAVE DIMINISHED AND
THIS TREND WILL CONT OVERNIGHT. WEAK UPPER LEVEL RIDGING OVER THE
GULF WILL EXPAND TOWARD THE COAST TONIGHT INTO SUNDAY MORNING
SHUNTING MUCH OF THE PRECIP TO THE WEST OVERNIGHT INTO SUNDAY. AT
THE SURFACE...A SURGE OF DRIER AIR WILL WORK INTO THE REGION FROM
THE NORTHEAST. FEEL RAIN CHANCES WILL BE ON THE LOW SIDE FOR MUCH
OF SUNDAY. A WEAK DISTURBANCE WILL APPROACH SE TX LATE SUNDAY AND
SOME LIGHT RAIN IS EXPECTED OVER THE W-NW PARTS OF THE REGION
TOWARD EVENING. THE REAL FUN AND GAMES BEGIN LATE SUNDAY NIGHT AND
MONDAY. AN UPPER LEVEL LOW OVER THE PANHANDLE WILL DIG SOUTH.
ISENTROPIC UPGLIDE WILL INCREASE AS A SERIES OF UPPER LEVEL
DISTURBANCES MOVE ACROSS EAST TEXAS. LIFT WILL INCREASE AS THE
UPPER LEVEL LOW APPROACHES. A SURFACE LOW WILL DEVELOP OVER THE
GULF AND MOVE PARALLEL TO THE COAST TOWARD SOUTHERN LOUISIANA. THE
COMBINATION OF ALL THESE FEATURES WILL YIELD HIGH RAIN CHANCES FOR
MONDAY INTO MONDAY NIGHT. THE UPPER LEVEL LOW WILL MOVE DIRECTLY
OVERHEAD ON TUESDAY AND THIS WILL LIKELY KEEP RAIN CHANCES IN THE
FCST THROUGH TUESDAY. RAINFALL TOTALS MONDAY THROUGH TUESDAY WILL
AVERAGE 1 TO 2 INCHES WITH SOME LOCALLY HIGHER AMOUNTS.

THERE IS SOME POTENTIAL FOR WINTER WEATHER LATE SUNDAY NIGHT INTO
EARLY MONDAY...MAINLY NORTH OF A CALDWELL TO TRINITY. THE AIR MASS
ON SUNDAY WILL BE DRY AS DEW PTS FALL INTO THE LOWER 20S. AS
PRECIP FALLS INTO THIS DRY AIR...EVAPORATIVE COOLING WILL ALSO
ALLOW THE AIR TEMP TO FALL. THERE IS A SLIGHT POSSIBILITY THAT
TEMPERATURES COULD BRIEFLY FALL BELOW FREEZING. IF THIS
OCCURS...THERE COULD BE A BRIEF WINDOW OF FREEZING RAIN OR SLEET.
MODELS ARE COMING INTO BETTER AGREEMENT THAT TEMPERATURES WILL
STAY JUST WARM ENOUGH FOR THE PRECIPITATION TO REMAIN RAIN.

THERE IS ALSO SOME POTENTIAL FOR WINTER WEATHER AS THE UPPER LOW
MOVES OVERHEAD ON TUESDAY. ACTUALLY FEEL THE POTENTIAL ON TUESDAY
IS A BIT BETTER THAN MONDAY MORNING. STILL A GREAT DEAL OF
UNCERTAINTY WITH REGARDS TO AVAILABLE MOISTURE BUT THERMAL
PROFILES LOOK COLD ENOUGH TO SUPPORT SLEET...MAINLY NORTH OF A
BRENHAM TO CLEVELAND LINE. 850 TEMPS ON TUES MORNING FALL TO -1 TO
-2 C AND 925 MB TEMPS ARE ALSO BETWEEN -1 AND -2 C DEGREES.
SURFACE TEMPS WILL BE AROUND 34 F SO THERE WON`T BE ENOUGH TIME
FOR THE ICE PELLETS TO MELT. THICKNESS VALUES ARE MARGINAL BUT
LOOK TOO HIGH FOR SNOW AT THIS TIME BUT UPPER LEVEL LOWS ARE
NOTORIOUSLY TRICKY AND CAN PACK A LOT OF COLD AIR ALOFT.

TEMPS ON MONDAY WILL BE COLD AS CLOUDS AND RAIN LIMIT THE WARM
UP. TEMPS GRADUALLY WARM THROUGH THE WEEK BUT MAX TEMPS LOOK TO
REMAIN BELOW SEASONAL NORMALS THROUGH FRIDAY AS WEAK RIDGING ALOFT
GENTLY AMPLIFIES. OVERNIGHT LOW TEMPS WILL APPROACH FREEZING WED
MORNING AND LIKELY FALL BELOW FREEZING ON THANKSGIVING MORNING.
FREEZING TEMPS WILL BE POSSIBLE AS FAR SOUTH AS HOUSTON ON THURS
MORNING.

[skidog40]

If there is any cloud clearing at night wouldn't that lower temperatures even further? and would colder temperatures be expected when rain arrives?

[kayci]

Okay yall.... laymans terms.. are we gonna be wet/cold/icy tomorrow (sunday) around the winnie area???? gotta know now... sorry kinda in a hurry to find out.

[srainhoutx]

If there is any cloud clearing at night wouldn't that lower temperatures even further? and would colder temperatures be expected when rain arrives?

I doubt the clouds will move out before sometime Tuesday, skidog. Some drier air will filter in briefly early tomorrow before the main storm system and the Coastal Low get going late tomorrow.

[srainhoutx]

Okay yall.... laymans terms.. are we gonna be wet/cold/icy tomorrow (sunday) around the winnie area???? gotta know now... sorry kinda in a hurry to find out.

Travel to Winnie should be fine during the day tomorrow, kayci. Tomorrow night could get very wet and breezy. No wintry mischief down here tomorrow during the day and early evening.

[skidog40]

Strange radar imagery from the northeast to the southwest, the cloud cover seems strange to me, no flow to it

[Andrew]

Strange radar imagery from the northeast to the southwest, the cloud cover seems strange to me, no flow to it

What are you confused on skidog?

[Andrew]

00z NAM is too dry already. Underestimating the closed low. We can throw out that run. On to the gfs.

[Belmer]

00z NAM is too dry already. Underestimating the closed low. We can throw out that run. On to the gfs.

Agreed. Even the 00z GFS is being a little bullish. Feel like models are just having a hard time with this low and underestimating it.

[Andrew]

00z NAM is too dry already. Underestimating the closed low. We can throw out that run. On to the gfs.

Agreed. Even the 00z GFS is being a little bullish. Feel like models are just having a hard time with this low and underestimating it.

I was over on storm2k and actually reading (and it made sense) that it could have been a reporting error. Some of the central/North central Texas sites there were dew-point readings of -30C in the upper levels which seems a little extreme.

[unome]

a chilly week for certain, but it looks like beautiful sunshine for Thanksgiving, so I am thankful :)

http://www.nws.noaa.gov/wtf/udaf/MapCli ... C&area=809

[Portastorm]

NWSFO Austin/San Antonio (EWX) has backed way off from its more bullish forecast yesterday. The Austin metro area is no longer under a Winter Storm Warning and under no advisory whatsoever. There's a string of counties in the Hill Country under a Winter Weather Advisory. Guess the overnight "warm" model trends convinced 'em to back off.

I know this much, our dew points continue to fall and have dropped about 10 degrees (38 to 28) in the last 7-8 hours. There clearly is some drier air above but with the onset of any precip, wet-bulb cooling will pull current surface temps around 40 easily down into the lower 30s.

[srainhoutx]

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
932 AM CST SUN NOV 24 2013

.UPDATE...
HAVE EXPANDED THE CURRENT WINTER WEATHER ADVISORY FARTHER EASTWARD
TO INCLUDE THE NORTHEASTERN PORTION OF THE I-35 CORRIDOR.

&&

.DISCUSSION...
LOWER DEWPOINTS ARE ADVECTING INTO OUR NORTHEASTERN COUNTIES THIS
MORNING...AND WILL CONTINUE THROUGH THIS AFTERNOON AS NORTHEASTERLY
WINDS PERSIST. LIGHT SLEET HAS BEGUN TO MIX-IN WITH THE COLD RAIN
MOVING ACROSS THE AREA...MAINLY ACROSS THE EASTERN HILL COUNTRY
AND ADJACENT AREAS. ADDITIONAL PERIODS OF RAIN ARE EXPECTED
THROUGHOUT THE DAY AND TONIGHT...WITH OCCASIONAL LIGHT SLEET
EXPECTED ACROSS NORTHERN/NORTHEASTERN PORTIONS OF THE CWA. MINIMAL
TO NO ACCUMULATIONS OF FROZEN PRECIPITATION IS EXPECTED DUE TO
SURFACE TEMPERATURES REMAINING ABOVE FREEZING. HOWEVER...LIGHT
ACCUMULATIONS ARE POSSIBLE ACROSS BRIDGES...OVERPASSES AND OTHER
EXPOSED AND/OR RAISED AREAS. THE WINTER WEATHER ADVISORY HAS BEEN
UPDATED. PLEASE REFER TO THE WSWEWX PRODUCT FOR ADDITIONAL
DETAILS.