[MCD] SWOMCD

Sat Jan 13 00:04:04 UTC 2007

ACUS11 KWNS 130007
SWOMCD
SPC MCD 130006 
OKZ000-130300-

MESOSCALE DISCUSSION 0045
NWS STORM PREDICTION CENTER NORMAN OK
0606 PM CST FRI JAN 12 2007

AREAS AFFECTED...CNTRL/ERN OK

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 130006Z - 130300Z

LARGE SHIELD OF PCPN CONTINUES ACROSS CNTRL/ERN PARTS OF OK EARLY
THIS EVE.  PRECIPITATION-TYPE HAS REMAINED THE MOST DIFFICULT
CHALLENGE WITH THIS FIRST WAVE OF PCPN.  00Z OUN SOUNDING SHOWED A
SUBSTANTIAL WARM NOSE /PLUS 10.5 DEG C JUST BELOW H85/...BUT COOLEST
PART OF THE 1700 FT DEEP SFC-BASED COLD DOME WAS AROUND MINUS 5 DEG
C.  RESEARCH HAS SHOWN THAT SOME ICE NUCLEI CAN ACTIVATE AT
TEMPERATURES AROUND MINUS 4-5 DEG C...THOUGH THE PROBABILITY AT THAT
TEMPERATURE IS ONLY AROUND 20 PERCENT.  PRESUMABLY...GIVEN THE
PREDOMINANCE OF SLEET AND SNOW ACROSS CNTRL OK...THIS PROCESS
DOMINATED TODAY.

BACK EDGE OF THE PCPN SHIELD APPEARS TO BE ACCELERATING ENEWD ACROSS
CNTRL OK ATTM...SIMILAR TO 18Z NAM AND 21Z SREF SOLUTIONS.  THIS
WOULD SUGGEST A DECREASING PCPN TREND ACROSS NERN OK BY 03Z.  THE
SAME MODELS...HOWEVER...INDICATE THAT THE HEAVIER RAINFALL IN THE
DFW METROPLEX WILL TRANSLATE ENEWD ACROSS SCNTRL/SERN INTO ECNTRL OK
00-06Z.  THUS...THERE MAY BE A CONTINUATION OF HOURLY RATES OF 0.10+
INCH FROM VCNTY KMLC NEWD TOWARD KFYV THROUGH 06Z. 
OTHERWISE...FARTHER N...THE DECREASE IN PCPN RATES WILL LIKELY BE
REPLACED WITH FREEZING DRIZZLE AND OR SPORADIC SLEET SHOWERS.

SFC FREEZING LINE WILL LIKELY REMAIN QUASI-STATIONARY OWING TO THE
HIGHER ERN OK TERRAIN AND PRESENCE OF STRONGER PRESSURE RISES WELL
NE OF THE REGION.  THUS...PRECIPITATION TYPE WILL PROBABLY REMAIN
STATUS-QUO THROUGH LATE EVENING.  MORE SPECIFICALLY...A ZONE OF
FREEZING RAIN WITH SIGNIFICANT ICING SHOULD EXIST FROM KMLC-KFYV
WITH A TENDENCY FOR MORE SLEET MIXED IN N OF I-40 THROUGH LATE
EVENING.

..RACY.. 01/13/2007

...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...TSA...OUN...

34739841 35799785 36569675 36809568 36429477 35919458
35019479 34429551 34179665 34299797 34469847 