[MCD] SWOMCD

[Mesoscale Convective Discussions]

ACUS11 KWNS 191215
SWOMCD
SPC MCD 191215 
TXZ000-OKZ000-191615-

MESOSCALE DISCUSSION 2278
NWS STORM PREDICTION CENTER NORMAN OK
0615 AM CST TUE DEC 19 2006

AREAS AFFECTED...CNTRL/ERN PORTIONS OF THE TX/OK PNHDLS

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 191215Z - 191615Z

SHOWERS OF FREEZING RAIN MIXED AT TIMES WITH SLEET WILL CONTINUE
THROUGH THE MORNING ACROSS THE SRN HIGH PLAINS.  THE MOST PERSISTENT
REGENERATION OF SHOWERS WITH HEAVIEST PCPN RATES /UP TO 0.15 INCH
PER HOUR/ WILL LIKELY EXIST IN A 50-60 NM WIDE AREA CENTERED ON A
LINE EXTENDING FROM NEAR KPVW-KBGD-30SE KLBL.

UPPER LOW WAS BEGINNING TO TURN EWD OVER THE LWR CO RVR VLY THIS
MORNING WITH AN EXPANSIVE WARM CONVEYOR STREAMING FROM THE
SUB-TROPICAL PAC NEWD TO THE SRN HIGH PLAINS.  A DRY SLOT WAS
EVIDENT IN WATER VAPOR IMAGERY OVER SCNTRL NM AND SHORT TERM MODELS
SUGGEST THAT THIS MAY ENCROACH ON THE WRN TX PNHDL WITH TIME THIS
MORNING.  HOWEVER...INSPECTION OF THE 295-305K LAYERS SUGGESTS THAT
ISENTROPIC LIFT WILL REMAIN STRONG FROM THE CNTRL S PLAINS NEWD INTO
THE CNTRL/ERN TX/OK PNHDLS THROUGH AT LEAST 18Z. IN FACT...MUCAPES
OF A COUPLE HUNDRED J PER KG WILL MAINTAIN THE TSTM THREAT...LOCALLY
ENHANCING PCPN RATES.

12Z TEXAS MESONET OBS PLACE THE SFC FREEZING LINE FROM SEMINOLE NEWD
THROUGH TAHOKA-SPUR-MEMPHIS AND INTO ROGER MILLS COUNTY OK.  THE
FREEZING LINE MAY RETREAT A BIT NWWD THIS MORNING AS LOW-LEVEL WARM
ADVECTION CONTINUES...BUT AREAS ROUGHLY FROM KLBB-KAMA TO THE OK
PNHDL SHOULD REMAIN FIRMLY AOB 30 DEG F WHERE PCPN CONTINUES TO
COUNTERACT A FLOW OF RELATIVELY DRY NEAR-SFC AIR TRAJECTORIES. 
P-TYPE SHOULD MOSTLY REMAIN FREEZING RAIN OWING TO THE PLUS 4-5 DEG
C WARM LAYER JUST ABOVE H8 NOTED ON THE 12Z AMA SOUNDING.  SLEET MAY
MIX WITH THE FREEZING RAIN IN THE HEAVIER TSTMS.

..RACY.. 12/19/2006

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

...NOTICE...
SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A
SCHEDULED BASIS FROM DECEMBER 1 THROUGH FEBRUARY 28...FOUR
TIMES A DAY...AROUND 00 UTC...06 UTC...12 UTC...AND 18 UTC
FOR SIGNIFICANT SHORT RANGE WINTER WEATHER EVENTS.

ATTN...WFO...LUB...AMA...

35080200 35850170 36800113 36890021 36540006 35310056
34720088 34080119 33880156 34130200 34680212