646 
FXUS63 KTOP 182047
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
347 PM CDT MON MAR 18 2013

.DISCUSSION...

SHORT TERM - THROUGH TUESDAY...

FIRE WEATHER CONCERNS AND A FEW CHANCES FOR LIGHT PRECIP ARE THE 
MAIN FOCUS IN THE SHORT TERM. PARTLY CLOUDY SKIES AND A STOUT 
NORTHWEST BREEZE WERE IN PLACE OVER THE FORECAST AREA THIS AFTERNOON 
AS STRONG LOW PRESSURE WAS LIFTING EAST ACROSS THE GREAT LAKES AND A 
RIDGE OF HIGH PRESSURE WAS SETTLING IN TO THE HIGH PLAINS. 
TEMPERATURES HAD WARMED INTO THE 50S AMID RATHER DEEP MIXING AND 
PLENTY OF SUNSHINE. THE WINDS WILL CONTINUE TO GUST UNTIL JUST AFTER 
SUNSET BEFORE TAPERING OFF. TEMPS SHOULD DROP OFF PRETTY QUICKLY 
WITH THE WINDS UNDER MOSTLY CLEAR SKIES BUT DO EXPECT SOME MID LEVEL 
CLOUD COVER TO DEVELOP AND MOVE INTO THE AREA OVERNIGHT AS A WEAK 
SHORT WAVE TROUGH FOCUSES SOME ASCENT OVER THE AREA. THIS MID LEVEL 
MOISTURE AND LIFT MAY BE SUFFICIENT TO PRODUCE LIGHT SNOW SHOWERS 
ALOFT...PARTICULARLY WHEN PAIRED WITH THE POTENTIAL FOR SOME WEAK 
CONVECTIVE INSTABILITY ABOVE THE MOIST LAYER. DRY AIR IN THE LOW 
LEVELS SHOULD LIMIT ANY POTENTIAL FOR MORE THAN FLURRIES AT THE 
SURFACE AS THE MAJORITY OF SNOW SHOULD SUBLIMATE BEFORE REACHING THE 
SURFACE. A FEW OF THE HEAVIER SHOWERS MAY RESULT IN A QUICK BURST OF 
SNOW THOUGH.

ON TUESDAY EXPECT VERY DEEP MIXING THROUGH THE BOUNDARY LAYER UP TO 
AROUND 7K FEET OR MORE. DESPITE THE STRONG MIXING...THE AIRMASS AT 
THE TOP OF THE PROJECTED MIXED LAYER IS ACTUALLY RELATIVELY MOIST 
AND NOT PARTICULARLY WINDY. SO WHILE THE LOW LEVEL RH AND WINDS MAY 
BE SUFFICIENT TO SUPPORT A VERY HIGH FIRE DANGER...PARTICULARLY IN 
CENTRAL KANSAS...DO NOT EXPECT RED FLAG CRITERIA TO BE MET. STEEP 
LAPSE RATES JUST ABOVE THE BOUNDARY LAYER APPEAR TO RESULT IN SOME 
SMALL AMOUNTS OF CAPE...AND COULD ACTUALLY SEE SOME HIGH BASED 
CONVECTION DEVELOP. THE CURRENT EXPECTATION IS THAT ANY SHOWERS 
WOULD BE SO HIGH BASED WITH DRY AIR UNDERNEATH THAT LITTLER MORE 
THAN SCATTERED SPRINKLES ARE EXPECTED. TEMPERATURES SHOULD WARM 
NICELY TOMORROW INTO THE UPPER 40S TO MID 50S ALTHOUGH THERE IS SOME 
POTENTIAL FOR THICKER CLOUD COVER WITH THE SHALLOW CONVECTION WHICH 
WOULD LIMIT HIGHS A BIT.

BARJENBRUCH

MID RANGE FORECAST (WEDNESDAY AND THURSDAY)...

MEDIUM RANGE MODELS PERSIST IN DEVELOPING A BAND OF RAIN THEN SNOW 
FOR THE LATTER HALF OF THE WEEK...MAINLY ACROSS CENTRAL AND EAST 
CENTRAL KANSAS. MODELS PROG A FAIRLY STRONG SURFACE LOW TO FORM 
ACROSS THE HIGH PLAINS WEDNESDAY NIGHT...WHICH WILL BRING A FETCH OF 
WARM AIR AND MOISTURE TO THE NORTH FROM THE GULF OF MEXICO. THIS 
SURFACE LOW LOOKS LIKE IT WILL SLIDE TO THE SOUTHEAST ACROSS WESTERN 
OKLAHOMA INTO TEXAS. GIVEN THAT NORTHEAST AND EAST CENTRAL KANSAS 
WILL REMAIN NORTH OF THE LOW THE SURFACE WARM FRONT WILL LIKELY NOT 
APPROACH THE AREA LEAVING US IN COLD AIR WITH EASTERLY WINDS. 
ISENTROPIC LIFT EVIDENT ON 290 K TO 305 K THETA E SURFACES SHOW GOOD 
ASCENT WITH NEARLY COMPLETE SATURATION THROUGH 500 MB. THIS WILL 
ALLOW FOR EFFICIENT PRECIPITATION TO COMMENCE ACROSS CENTRAL AND 
EAST CENTRAL KANSAS THURSDAY MORNING. GFS FORECAST SOUNDINGS 
INDICATE THAT THE THERMAL PROFILE WILL SUPPORT MOSTLY SNOW WITH THIS 
SYSTEM...BUT GIVEN HOW WARM/MOIST THE LOW LEVELS WILL BE WILL HOLD 
OFF ON GETTING TOO SPECIFIC REGARDING SNOW AMOUNTS. IT DOES LOOK AS 
THOUGH THE STRONG FETCH FROM THE GULF OF MEXICO WILL PROVIDE THE 
ATMOSPHERE WITH ENOUGH MOISTURE TO BRING A DECENT AMOUNT OF 
PRECIPITATION. SHOULD THE VERTICAL TEMPERATURE PROFILES CONTINUE TO 
INDICATE ALL SNOW...ITS POSSIBLE THAT PORTIONS OF EAST CENTRAL 
KANSAS AND SOUTHWEST MISSOURI COULD SEE DECENT SNOW ACCUMULATIONS 
THURSDAY THROUGH FRIDAY. AGAIN...GIVEN UNCERTAINTY WITH RESPECT TO 
PLACEMENT AND THERMAL PROFILE WILL HOLD OFF ON TRYING TO NAIL 
SPECIFIC AMOUNTS AT THIS TIME. 

JL

FRIDAY THROUGH MONDAY...

BY FRIDAY THE SHORTWAVE RESPONSIBLE FOR THE PRECIP ACROSS THE AREA 
WILL BE ADVANCING INTO THE CENTRAL PLAINS. THE CHANCE OF SNOW WILL 
LINGER THROUGH THE DAY FRIDAY AS THE SYSTEM PROGRESSES EASTWARD AND 
A LOW PRESSURE MOVES THROUGH TX/OK. WAA WILL CONTINUE TO SUPPLY 
MOISTURE NORTHWARD INTO THE COLD AIR IN PLACE ACROSS THE AREA. ONCE 
THAT SYSTEM DEPARTS ANOTHER SHORTWAVE WILL DIVE SOUTHEAST INTO THE 
CENTRAL AND SOUTHERN PLAINS THIS WEEKEND. AT THIS POINT THE MODELS 
BEGIN TO DIFFER ON THE EVOLUTION OF THE SYSTEM. HAVE KEPT A SLIGHT 
CHANCE FOR RAIN/SNOW DURING THE DAY ON SATURDAY GIVEN THAT THE GFS 
BRINGS WARMER LOW AND MID LEVEL TEMPS...NO LONGER SUPPORTING THE 
FORMATION OF SNOW. AS THE SHORTWAVE MOVES INTO THE MID MS VALLEY 
COLD AIR WRAPS AROUND THE BACKSIDE OF THE SYSTEM SUPPORTING SNOW ON 
SUNDAY. THE ECMWF KEEPS THE COLD AIR IN PLACE THROUGH THE ENTIRE 
PERIOD BUT THE SYSTEM DOES NOT DEVELOP PRECIP ACROSS THE AREA...ATTM 
CONFIDENCE IS LOW GIVEN THE MODEL SOLUTIONS.

SANDERS

&&

.AVIATION...

VFR CONDITIONS WITH GUSTY NORTHWEST WINDS ARE EXPECTED THROUGH
SUNSET. WINDS WILL TAPER AFTER 01Z. AN AREA OF CLOUDS IN THE 5K TO
10K RANGE SHOULD MOVE INTO NORTHEAST KANSAS BY LATE EVENING WITH A
FEW FLURRIES POSSIBLE BETWEEN 06Z AND 10Z...BUT FLIGHT IMPACTS
APPEAR UNLIKELY AT TAF SITES.

BARJENBRUCH


&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$