MESO: Mesoscale Discussion 0424

ACUS11 KWNS 101033
SWOMCD
SPC MCD 101032
KSZ000-OKZ000-TXZ000-101430-

MESOSCALE DISCUSSION 0424
NWS STORM PREDICTION CENTER NORMAN OK
0532 AM CDT WED APR 10 2013

AREAS AFFECTED...WRN/CNTRL OK...SOUTH CENTRAL KS...EXTREME NW TX

CONCERNING...WINTER MIXED PRECIPITATION

VALID 101032Z - 101430Z

SUMMARY...FREEZING RAIN AND SLEET WILL CONTINUE ACROSS WRN/CNTRL OK
INTO S-CENTRAL KS THROUGH THE MORNING HOURS...WITH A SLOW EWD
PROGRESSION OF THE FREEZING LINE EXPECTED. MODERATE/LOCALLY HEAVY
PRECIP RATES WILL CONTINUE TO BE POSSIBLE WITH STRONGER CONVECTIVE
ELEMENTS.

DISCUSSION...A PERSISTENT PLUME OF ELEVATED CONVECTION ATOP A VERY
COLD ARCTIC AIRMASS HAS ALREADY PRODUCED WIDESPREAD FREEZING
RAIN/SLEET ACROSS WRN OK INTO SRN KS. THIS ACTIVITY CONTINUES TO
DEVELOP IN A ZONE OF ASCENT AHEAD OF A STRONG UPPER TROUGH WHICH IS
BEGINNING TO PROGRESS EWD OUT OF CO/NM. STEEP LAPSE RATES AND
PLENTIFUL MOISTURE ABOVE THE FRONTAL SURFACE ARE PROVIDING MORE THAN
SUFFICIENT BUOYANCY FOR GENERATION AND MAINTENANCE OF DEEP
CONVECTION ACROSS MUCH OF OK INTO SRN KS.

TSTM INTENSITY MAY BEGIN TO WANE OVER THE NEXT FEW HOURS AS
WIDESPREAD CONVECTION PROCESSES THE FAVORABLE LAPSE RATES.
HOWEVER...INCREASING ASCENT AHEAD OF THE EJECTING UPPER SYSTEM WILL
MAINTAIN A LARGE SHIELD OF WINTER PRECIP FOR SEVERAL MORE
HOURS...WITH EMBEDDED CONVECTIVE ELEMENTS CAPABLE OF
LIQUID-EQUIVALENT PRECIP RATES AOA 0.1 IN/HR.

AT THE SURFACE...THE FREEZING LINE HAS BEEN MOVING VERY SLOWLY EWD
OVERNIGHT. THIS EWD PROGRESS IS EXPECTED TO CONTINUE AS WEAK COLD
ADVECTION PERSISTS THROUGH THE EARLY MORNING...WITH FREEZING RAIN
EXPECTED TO REACH A SPS-OUN-SWO-WLD-MHK LINE BY 12Z. MEANWHILE...THE
WESTERN EDGE OF THE PRECIP SHIELD IS EXPECTED TO BECOME PRIMARILY
SLEET AS COLD AIR DEEPENS FROM WEST TO EAST.

THOUGH GROUND TEMPS ARE WARM...FREEZING RAIN WILL CONTINUE TO POSE A
THREAT OF ACCUMULATION ON ELEVATED SURFACES...WHILE SLEET
ACCUMULATIONS WILL HAVE AN ADVERSE EFFECT ON ROAD CONDITIONS.

..DEAN.. 04/10/2013

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

ATTN...WFO...TSA...TOP...ICT...OUN...DDC...

LAT...LON 33999937 34159979 34669993 35399994 36119972 36849939
37539904 38119861 38739797 38909715 39049653 38329597
36249665 35639691 35019712 34579746 34269789 33949825
33919883 33999937

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