MESO: Mesoscale Discussion 2378

ACUS11 KWNS 191843
SWOMCD
SPC MCD 191843
OKZ000-KSZ000-TXZ000-COZ000-NMZ000-192315-

MESOSCALE DISCUSSION 2378
NWS STORM PREDICTION CENTER NORMAN OK
1243 PM CST MON DEC 19 2011

AREAS AFFECTED...NERN NM / NWRN TX PANHANDLE / WRN OK PANHANDLE /
SERN CO / SWRN KS

CONCERNING...HEAVY SNOW

VALID 191843Z - 192315Z

INITIALLY LIGHT TO MODERATE SNOWFALL RATES WILL TRANSITION TO HEAVY
SNOWFALL RATES THIS AFTERNOON. SNOWFALL RATES AOA 1 INCH/HR WILL
BECOME LIKELY FIRST W OF 102 DEG LONGITUDE /I.E. CO/KS BORDER/ AND
THEN SPREAD INTO SWRN KS. LOCALIZED BLIZZARD CONDITIONS WILL TEND
TO INCREASE IN COVERAGE BY LATE AFTERNOON.

SURFACE MESOANALYSIS SHOWS A SURFACE LOW OVER E-CNTRL NM WITH A SW
TO NE ORIENTED BAROCLINIC ZONE FROM THE LOW NEWD AND BISECTING THE
TX PANHANDLE AND EXTENDING INTO SWRN KS. APPRECIABLE SURFACE
PRESSURE RISES --NOTED EARLIER THIS MORNING-- BEHIND THE FRONT AND A
STRENGTHENING LOW LEVEL PRESSURE GRADIENT WILL LEAD TO INCREASING
NLY WINDS AND COINCIDE WITH INCREASING LOW LEVEL COLD AIR ADVECTION
ON THE POLEWARD/BACKSIDE SIDE OF THE EWD MIGRATING SURFACE CYCLONE.
THIS WILL ALLOW THE COLUMN TO GRADUALLY COOL AND SUPPORT A PHASE
CHANGE TO ALL SNOW ACROSS PARTS OF THE TX-OK PANHANDLES.

DEEP LAYER ASCENT WILL BECOME MAXIMIZED OVER THE REGION LATER THIS
AFTERNOON AS STRONG UPPER FORCING FOR ASCENT OVERSPREADS THE
STRENGTHENING BAROCLINIC ZONE AND IN TURN LEADS TO HEAVIER SNOWFALL
RATES /21-00Z/. THE POSSIBILITY OF CONVECTIVE ENHANCEMENT
/THUNDERSNOW/ APPEARS TO INCREASE TOWARDS 00Z INVOF THE NRN TX
PANHANDLE/OK PANHANDLE. IT IS HERE...THAT FORECAST SOUNDINGS SHOW
MID-LEVEL LAPSE RATES STEEPENING AS THE NOSE OF THE MID-LEVEL DRY
SLOT MOVES N FROM THE TX S PLAINS AND ENCROACHES UPON THE TX-OK
PANHANDLES THIS AFTERNOON. THE LATEST SREF PROBABILITY GUIDANCE AND
EXPERIMENTAL CONVECTION-ALLOWING ENSEMBLE /SSEO/ SHOW A SWATH OF 1
INCH/HR RATES FROM NE NM INTO SWRN KS /LOCALLY HEAVIEST NEAR THE 5
STATE BORDER REGION/. A SUBSTANTIAL REDUCTION IN VISIBILITIES AND
INCREASINGLY STRONG WIND GUSTS WITH TIME MAY YIELD INCREASING
COVERAGE OF LOCALIZED BLIZZARD CONDITIONS BY LATE THIS AFTERNOON.

..SMITH.. 12/19/2011

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...DDC...GLD...AMA...PUB...ABQ...

LAT...LON 35100313 35320489 36510460 37790449 38410155 37260133
35100313

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