Re: January 2013: Potential Late Week Wintry WX Central TX?
Posted: Wed Jan 02, 2013 7:00 am
Winter Storm Watches have been hoisted for El Paso to Presidio into the Big Bend Region on E into Alpine for 4-6 inches of snow. NWS San Angelo has issued a SPS regarding a rain/snow mix extending E as far as Brownwood. NWS San Antonio/Austin now talking about the first snow of the season for the Edwards Plateau and Hill Country. NWS Houston/Galveston does mention a 20% chance of light rain on Saturday. Depending on timing and just how much the dry air at the surface can moisten up, I guess a stray ice pellet or two may not be out of the question. As always, these type events are also difficult to forecast and often come as a surprise. We'll see what the next 24 hours or so holds and just how strong the upper level low is as it ejects across W Texas.
HPC:
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD
351 AM EST WED JAN 02 2013
VALID 12Z WED JAN 02 2013 - 12Z FRI JAN 04 2013
...RATHER QUIESCENT CONDITIONS SHOULD PERSIST OVER MUCH OF THE
REMAINDER OF THE CONUS...
...ACCUMULATING SNOWS WILL FOCUS OVER THE GREAT LAKES REGION AS
WELL AS ACROSS SOUTHWEST TEXAS...
MOISTURE AS A WHOLE SHOULD REMAIN RATHER LIMITED AS A FRONTAL
BOUNDARY SINKS SOUTHWARD INTO THE GULF OF MEXICO. MUCH OF THE
MOISTURE FROM THE GULF WILL POOL NORTHWARD FOCUSING AN AXIS OF
SCATTERED RAIN SHOWERS ALONG THE IMMEDIATE GULF COAST.
HOWEVER...THE MID-LEVEL PATTERN WILL NOT BE VERY SUPPORTIVE FOR
MORE WIDESPREAD PRECIPITATION EXCEPT FOR THE FEW WEAK IMPULSES
EMERGING WITHIN THE BROADER SCALE SOUTHWESTERLY FLOW. WHILE IT
WILL NOT BE A SOAKER ALONG THE GULF COAST...SCATTERED SHOWERS ARE
FORECAST TO IMPACT THE REGION THE NEXT COUPLE OF DAYS GIVEN THE
PRESENCE OF THE STALLED BOUNDARY OVER THE CENTRAL GULF. LOOKING
FURTHER UPSTREAM...A CLOSED UPPER LOW DROPPING SOUTH TO
SOUTHEASTWARD INTO NORTHERN BAJA CALIFORNIA WILL BE THE NEXT
PRECIPITATION MAKER TO SECTIONS OF SOUTHERN NEW MEXICO AND INTO
WEST TEXAS. LOW-LEVEL TEMPERATURES ARE FORECAST TO BE AROUND
FREEZING WHICH WILL ALLOW SNOW TO FALL OVER THIS REGION BY
THURSDAY AFTERNOON. THROUGH FRIDAY MORNING...THE HPC WINTER
WEATHER DESK IS ADVERTISING A FEW INCHES OF SNOW WITH POCKETS OF
SLIGHTLY HEAVIER AMOUNTS CLOSER TO THE RIO GRANDE RIVER.
LOOKING TO THE NORTH...AN UPPER RIDGE ANCHORING THE NORTHWESTERN
STATES WILL ALLOW AN EXPANSIVE TROUGH TO DEVELOP OVER THE
NORTH-CENTRAL CONUS AND OUT TOWARD THE NORTHEASTERN U.S. THE
SPARSE MOISTURE PROFILES WILL LIMIT PRECIPITATION FROM THESE
IMPULSES TRACKING THROUGH THE REGION. HOWEVER...LIGHT TO MODERATE
SNOW SHOWERS ARE EXPECTED TO DEVELOP OVER THE NORTHERN GREAT LAKES
AS A FRONTAL BOUNDARY SETS UP ORIENTED WEST-TO-EAST ALONG THE
LAKES. LOW-LEVEL LIFT AIDED BY THIS FRONT COMBINED WITH FAVORABLE
WIND TRAJECTORIES ALONG THE LAKE SURFACE WILL HELP INITIATE SNOW
SHOWERS THROUGHOUT THE PERIOD. 2 TO 4 INCHES OF SNOW WILL BE
POSSIBLE THROUGH FRIDAY MORNING WITH ISOLATED HEAVIER AMOUNTS
DOWNWIND OF LAKE ONTARIO.
THE INTERMOUNTAIN WEST WILL BE DOMINATED BY A SURFACE/UPPER RIDGE
WHICH SHOULD KEEP CONDITIONS RATHER QUIET THROUGHOUT MUCH OF THE
WEEK. IDEAL RADIATIONAL COOLING EFFECTS WILL LEAD TO SUB-ZERO
OVERNIGHT LOWS ACROSS CERTAIN AREAS WHILE HIGHS ONLY REBOUND INTO
THE TEENS AND 20S. THIS SETUP WILL ALSO ALLOW OFFSHORE FLOW TO
DOMINATE THE STATE OF CALIFORNIA. HOWEVER...THE PRESSURE GRADIENT
DOES NOT APPEAR TO BE SIGNIFICANT ENOUGH TO RESULT IN A STRONG
WIND EVENT.
RUBIN-OSTER
PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD
417 AM EST WED JAN 02 2013
VALID 12Z WED JAN 02 2013 - 12Z SAT JAN 05 2013
DAY 1...
THE PROBABILITY OF SIGNIFICANT SNOW AND/OR ICING IS LESS THAN 10
PERCENT.
DAY 2...
...WEST TEXAS / TRANS PECOS REGION...
A CLOSED LOW SEEN ON WV IMAGERY OFF THE SRN CA COAST THIS MORNING
WILL TRACK EWD ACROSS NWRN MEXICO TONIGHT...WHILE A NRN STREAM
TROUGH AXIS BEARS DOWN ACROSS THE SWRN U.S. FROM THE NORTH. THE
TWO WILL INTERACT THU INTO FRI RESULTING IN A CLOSED LOW OVER THE
SOUTHWEST. THE MODELS CONTINUE TO COME INTO BETTER AGREEMENT THIS
THIS SCENARIO AND INDICATE A SIGNIFICANT SNOW STORM FOR PORTIONS
OF WEST TEXAS / NRN MEXICO. ALTHOUGH THE UKMET IS DELAYED IN
CLOSING OFF A LOW...THERE IS GOOD CONSENSUS AMONG THE 00Z
NAM/GFS/ECMWF/CMC AND SREF/GEFS/EC ENSEMBLE MEANS AS WELL AS
RUN-TO-RUN AGREEMENT TO DISCOUNT THE 00Z UKMET. USED ROUGHLY EQUAL
WEIGHTING IN A BLEND OF THE NAM/GFS/ECMWF/SREF...NOT PUTTING TOO
MUCH WEIGHT ON THE NAM AS IT TENDS TO HAVE A COLD/WET BIAS.
DESPITE AN INITIALLY DRY ATMOSPHERE TO BATTLE...SNOW LOOKS TO
OVERSPREAD SWRN TEXAS WITH PERHAPS RAIN FOR THE LOWER ELEVATIONS
OF THE RIO GRANDE VALLEY THU MORNING...AS STRONG...DIFLUENT LIFT
ALOFT COMBINES WITH LOW LEVEL UPSLOPE FLOW IN CONNECTION TO
STRONG/COLD HIGH PRESSURE ANCHORED OVER THE PLAINS. MODEL FORECAST
SOUNDINGS INDICATE WARMING TO NEAR...BUT STILL BELOW 0 C...AT AND
BELOW 700 MB...WHICH COULD BE A TREND TOWARD SLEET MIXING IN. IN
ADDITION...THE LOWEST 10-15 KFT OF THE SOUNDING IS FCST ABOVE -10
C...INDICATIVE OF A HEAVY/HIGH DENSITY SNOW. SLR VALUES MAY
AVERAGE CLOSE TO 10:1 BUT PERHAPS A LITTLE GREATER IN THE HIGHER
ELEVATIONS. A SLIGHT RISK OF 4 INCHES WAS DRAWN FOR MUCH OF WEST
TEXAS INTO FAR SRN NEW MEXICO. A MODERATE RISK OF 4 WITH A SLIGHT
RISK OF 8 WAS DRAWN FOR THE HIGHER ELEVATIONS...ESPECIALLY INTO
THE DAVIS...GLASS AND CHINATI MOUNTAINS.
AS THE UPPER LOW BEGINS TO EJECT OUT TOWARD THE END OF DAY 2...FRI
MORNING...THE MID LEVEL JET COMING AROUND THE BASE OF THE LOW MAY
BRING IN ENOUGH DRY AIR ALOFT TO CAUSE ANY REMAINING PCPN TO FALL
AS FZDZ AS MODEL FCST SOUNDINGS INDICATE TO THE TOP OF THE
SATURATED LAYER NEAR OR ABOVE -10 C.
HPC:
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD
351 AM EST WED JAN 02 2013
VALID 12Z WED JAN 02 2013 - 12Z FRI JAN 04 2013
...RATHER QUIESCENT CONDITIONS SHOULD PERSIST OVER MUCH OF THE
REMAINDER OF THE CONUS...
...ACCUMULATING SNOWS WILL FOCUS OVER THE GREAT LAKES REGION AS
WELL AS ACROSS SOUTHWEST TEXAS...
MOISTURE AS A WHOLE SHOULD REMAIN RATHER LIMITED AS A FRONTAL
BOUNDARY SINKS SOUTHWARD INTO THE GULF OF MEXICO. MUCH OF THE
MOISTURE FROM THE GULF WILL POOL NORTHWARD FOCUSING AN AXIS OF
SCATTERED RAIN SHOWERS ALONG THE IMMEDIATE GULF COAST.
HOWEVER...THE MID-LEVEL PATTERN WILL NOT BE VERY SUPPORTIVE FOR
MORE WIDESPREAD PRECIPITATION EXCEPT FOR THE FEW WEAK IMPULSES
EMERGING WITHIN THE BROADER SCALE SOUTHWESTERLY FLOW. WHILE IT
WILL NOT BE A SOAKER ALONG THE GULF COAST...SCATTERED SHOWERS ARE
FORECAST TO IMPACT THE REGION THE NEXT COUPLE OF DAYS GIVEN THE
PRESENCE OF THE STALLED BOUNDARY OVER THE CENTRAL GULF. LOOKING
FURTHER UPSTREAM...A CLOSED UPPER LOW DROPPING SOUTH TO
SOUTHEASTWARD INTO NORTHERN BAJA CALIFORNIA WILL BE THE NEXT
PRECIPITATION MAKER TO SECTIONS OF SOUTHERN NEW MEXICO AND INTO
WEST TEXAS. LOW-LEVEL TEMPERATURES ARE FORECAST TO BE AROUND
FREEZING WHICH WILL ALLOW SNOW TO FALL OVER THIS REGION BY
THURSDAY AFTERNOON. THROUGH FRIDAY MORNING...THE HPC WINTER
WEATHER DESK IS ADVERTISING A FEW INCHES OF SNOW WITH POCKETS OF
SLIGHTLY HEAVIER AMOUNTS CLOSER TO THE RIO GRANDE RIVER.
LOOKING TO THE NORTH...AN UPPER RIDGE ANCHORING THE NORTHWESTERN
STATES WILL ALLOW AN EXPANSIVE TROUGH TO DEVELOP OVER THE
NORTH-CENTRAL CONUS AND OUT TOWARD THE NORTHEASTERN U.S. THE
SPARSE MOISTURE PROFILES WILL LIMIT PRECIPITATION FROM THESE
IMPULSES TRACKING THROUGH THE REGION. HOWEVER...LIGHT TO MODERATE
SNOW SHOWERS ARE EXPECTED TO DEVELOP OVER THE NORTHERN GREAT LAKES
AS A FRONTAL BOUNDARY SETS UP ORIENTED WEST-TO-EAST ALONG THE
LAKES. LOW-LEVEL LIFT AIDED BY THIS FRONT COMBINED WITH FAVORABLE
WIND TRAJECTORIES ALONG THE LAKE SURFACE WILL HELP INITIATE SNOW
SHOWERS THROUGHOUT THE PERIOD. 2 TO 4 INCHES OF SNOW WILL BE
POSSIBLE THROUGH FRIDAY MORNING WITH ISOLATED HEAVIER AMOUNTS
DOWNWIND OF LAKE ONTARIO.
THE INTERMOUNTAIN WEST WILL BE DOMINATED BY A SURFACE/UPPER RIDGE
WHICH SHOULD KEEP CONDITIONS RATHER QUIET THROUGHOUT MUCH OF THE
WEEK. IDEAL RADIATIONAL COOLING EFFECTS WILL LEAD TO SUB-ZERO
OVERNIGHT LOWS ACROSS CERTAIN AREAS WHILE HIGHS ONLY REBOUND INTO
THE TEENS AND 20S. THIS SETUP WILL ALSO ALLOW OFFSHORE FLOW TO
DOMINATE THE STATE OF CALIFORNIA. HOWEVER...THE PRESSURE GRADIENT
DOES NOT APPEAR TO BE SIGNIFICANT ENOUGH TO RESULT IN A STRONG
WIND EVENT.
RUBIN-OSTER
PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD
417 AM EST WED JAN 02 2013
VALID 12Z WED JAN 02 2013 - 12Z SAT JAN 05 2013
DAY 1...
THE PROBABILITY OF SIGNIFICANT SNOW AND/OR ICING IS LESS THAN 10
PERCENT.
DAY 2...
...WEST TEXAS / TRANS PECOS REGION...
A CLOSED LOW SEEN ON WV IMAGERY OFF THE SRN CA COAST THIS MORNING
WILL TRACK EWD ACROSS NWRN MEXICO TONIGHT...WHILE A NRN STREAM
TROUGH AXIS BEARS DOWN ACROSS THE SWRN U.S. FROM THE NORTH. THE
TWO WILL INTERACT THU INTO FRI RESULTING IN A CLOSED LOW OVER THE
SOUTHWEST. THE MODELS CONTINUE TO COME INTO BETTER AGREEMENT THIS
THIS SCENARIO AND INDICATE A SIGNIFICANT SNOW STORM FOR PORTIONS
OF WEST TEXAS / NRN MEXICO. ALTHOUGH THE UKMET IS DELAYED IN
CLOSING OFF A LOW...THERE IS GOOD CONSENSUS AMONG THE 00Z
NAM/GFS/ECMWF/CMC AND SREF/GEFS/EC ENSEMBLE MEANS AS WELL AS
RUN-TO-RUN AGREEMENT TO DISCOUNT THE 00Z UKMET. USED ROUGHLY EQUAL
WEIGHTING IN A BLEND OF THE NAM/GFS/ECMWF/SREF...NOT PUTTING TOO
MUCH WEIGHT ON THE NAM AS IT TENDS TO HAVE A COLD/WET BIAS.
DESPITE AN INITIALLY DRY ATMOSPHERE TO BATTLE...SNOW LOOKS TO
OVERSPREAD SWRN TEXAS WITH PERHAPS RAIN FOR THE LOWER ELEVATIONS
OF THE RIO GRANDE VALLEY THU MORNING...AS STRONG...DIFLUENT LIFT
ALOFT COMBINES WITH LOW LEVEL UPSLOPE FLOW IN CONNECTION TO
STRONG/COLD HIGH PRESSURE ANCHORED OVER THE PLAINS. MODEL FORECAST
SOUNDINGS INDICATE WARMING TO NEAR...BUT STILL BELOW 0 C...AT AND
BELOW 700 MB...WHICH COULD BE A TREND TOWARD SLEET MIXING IN. IN
ADDITION...THE LOWEST 10-15 KFT OF THE SOUNDING IS FCST ABOVE -10
C...INDICATIVE OF A HEAVY/HIGH DENSITY SNOW. SLR VALUES MAY
AVERAGE CLOSE TO 10:1 BUT PERHAPS A LITTLE GREATER IN THE HIGHER
ELEVATIONS. A SLIGHT RISK OF 4 INCHES WAS DRAWN FOR MUCH OF WEST
TEXAS INTO FAR SRN NEW MEXICO. A MODERATE RISK OF 4 WITH A SLIGHT
RISK OF 8 WAS DRAWN FOR THE HIGHER ELEVATIONS...ESPECIALLY INTO
THE DAVIS...GLASS AND CHINATI MOUNTAINS.
AS THE UPPER LOW BEGINS TO EJECT OUT TOWARD THE END OF DAY 2...FRI
MORNING...THE MID LEVEL JET COMING AROUND THE BASE OF THE LOW MAY
BRING IN ENOUGH DRY AIR ALOFT TO CAUSE ANY REMAINING PCPN TO FALL
AS FZDZ AS MODEL FCST SOUNDINGS INDICATE TO THE TOP OF THE
SATURATED LAYER NEAR OR ABOVE -10 C.