[MCD] SWOMCD

Mon Feb 20 06:31:53 UTC 2006

ACUS11 KWNS 200631
SWOMCD
SPC MCD 200630 
GAZ000-ALZ000-TNZ000-MSZ000-ARZ000-LAZ000-TXZ000-201230-

MESOSCALE DISCUSSION 0160
NWS STORM PREDICTION CENTER NORMAN OK
1230 AM CST MON FEB 20 2006

AREAS AFFECTED...NE TX/SRN AR/NRN LA/NRN MS/NRN AL/NW GA

CONCERNING...FREEZING RAIN 

VALID 200630Z - 201230Z

...FREEZING RAIN WILL CONTINUE THROUGH THE OVERNIGHT HOURS ACROSS A
LARGE PORTION OF THE GULF COAST STATES. OVERRUNNING PCPN ATOP ARCTIC
AIRMASS PRESENTS IDEAL SETUP FOR PROLONGED FZRA EVENT...

SUBTROPICAL MOIST CONVEYOR EVIDENT ON SATELLITE IMAGERY EXTENDS WEST
TO BAJA. SUBTLE IMPULSES RIDING THROUGH THIS FLOW ARE PROVIDING
ENOUGH SYNOPTIC SCALE VERTICAL MOTION FOR WIDESPREAD LIGHT PCPN. IN
ADDITION...850 MB EVENING UPPER AIR ANALYSIS REVEALS TIGHT FRONTAL
ZONE ACROSS NE TX/NRN LA/NRN GA. STRONG 40-50 KT LOW LEVEL JET /AS
OBSERVED BY AREA VWP DATA/ WILL TRANSPORT GULF MOISTURE OVER THE
FRONT. SFC FREEZING LINE EXTENDS FROM NEAR LFK ACROSS CNTRL LA AND
CNTRL MS JUST NORTH OF JAN INTO NRN AL AND EXTREME NW GA.

EVENING SOUNDINGS FROM JAN AND SHV DEPICT A DEEP WARM LAYER CENTERED
AROUND 850MB WHERE TEMPERATURES ARE WELL ABOVE FREEZING. THIS STRONG
INVERSION WILL BE MAINTAINED THROUGH THE OVERNIGHT HOURS...SO PCPN
TYPE WILL BE FREEZING RAIN GIVEN SUBFREEZING SFC TEMPERATURES. THE
SRN EXTENT OF THE FZRA WILL LIKELY BE FROM JUST SOUTH OF FORT POLK
LA TO NEAR OR JUST SOUTH OF JACKSON MS TO BIRMINGHAM AL. SFC WET
BULB TEMPS ARE AT OR NEAR FREEZING IN AREAS NORTH OF THIS LINE...SO
EVAPORATIONAL COOLING EFFECTS WILL ALLOW SFC TEMPS TO FALL TO 32F.

HOURLY PCPN RATES SHOULD BE RELATIVELY LIGHT...RANGING FROM AROUND
0.01 TO 0.05 INCHES PER HOUR. HOWEVER...ICING PROBLEMS WILL OCCUR
ESPECIALLY ON UNTREATED ROADS AND ELEVATED SURFACES.
ADDITIONALLY...LIGHT PCPN WILL CONTINUE FOR SEVERAL HOURS WHICH WILL
ALLOW SOME ICE ACCUMULATION.

..TAYLOR.. 02/20/2006

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

ATTN...WFO...FFC...OHX...BMX...HUN...MEG...JAN...LZK...LCH...SHV...

30979359 32409485 34349377 34879152 35068893 34878415
33858433 32548842 31219240 

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