000
FXUS63 KTOP 191233
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
733 AM CDT SUN MAY 19 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT SUN MAY 19 2013

SHORT TERM FORECAST (SUNDAY AND SUNDAY NIGHT)...

THE POTENTIAL FOR A SIGNIFICANT SEVERE WEATHER EVENT REMAINS IN TACT
FOR SUNDAY ACROSS ALL OF EASTERN KANSAS...WITH ALL HAZARDS OF SEVERE
WEATHER POSSIBLE INCLUDING LARGE DAMAGING HAIL...STRONG WINDS...AND
PERHAPS A TORNADO OR TWO.

THE INITIAL SURFACE OBSERVATION MAP INDICATES A RATHER WORKED OVER
LOW LEVEL ATMOSPHERE IN THE WAKE OF STRONG STORMS WHICH HAVE SINCE
LEFT THE AREA. PREVIOUS AS WELL AS ONGOING CONVECTION WILL LIKELY
CREATE AN OUTFLOW BOUNDARY IN THE KS/OK BORDER REGION...WHICH MAY
PLAY A ROLE IN THUNDERSTORM DEVELOPMENT AND BEHAVIOR FOR SUNDAY.
CURRENTLY LIGHT RAIN ASSOCIATED WITH POST OFB OVER RUNNING REMAIN IN
THE AREA...MAINLY ACROSS SOUTHERN KANSAS. DEPENDING ON HOW MUCH
SKIES CAN CLEAR ON SUNDAY WILL HELP DETERMINE HOW MUCH THE
ATMOSPHERE WILL BE ABLE TO DESTABILIZE FOR SUNDAY AFTERNOON. WATER
VAPOR IMAGERY AS WELL AS RAP40 H5 ANALYSIS INDICATE THE STRONG MID
LEVEL TROUGH...PARTIALLY RESPONSIBLE FOR SATURDAYS
CONVECTION...REMAINS IN PLACE OVER THE HIGH PLAINS AS IT GRADUALLY
MOVES EAST. AS THE DAY PROGRESSES H5 HEIGHT FALLS WILL BE PREVALENT
ACROSS THE AREA. WITH A MOIST BOUNDARY LAYER IN PLACE...ALONG WITH A
POTENT MID LEVEL TROUGH MOVING THROUGH THE AREA...EXPECT A PERIOD OF
SEVERE WEATHER TO TAKE PLACE LATER TODAY ACROSS EASTERN KANSAS.

ALL HIGH RESOLUTION SHORT RANGE MODELS PROG A QUICK RECOVERY OF THE
BOUNDARY LAYER MOISTURE AHEAD OF A DEEPENING SURFACE LOW COMING OFF
THE SOUTHERN/CENTRAL HIGH PLAINS. STRONG SOUTHERLY SFC FLOW WILL AID
IN THE BOUNDARY LAYER MOISTURE RECOVERY THROUGH THE MORNING AND
EARLY AFTERNOON HOURS ON SUNDAY. AN INITIAL ROUND OF ELEVATED
THUNDERSTORMS WILL BE POSSIBLE LATE SUNDAY MORNING...MAINLY NORTH OF
INTERSTATE 70 AS WARM AIR ADVECTION RIDES OVER THE LOW LEVEL
INVERSION. AROUND 2000-3000 J/KG OF ELEVATED INSTABILITY WILL BE
PRESENT AS WELL AS AROUND 40 KTS OF DEEP LAYER SHEAR FOR ANY STORM
TO TAP INTO...SO ROBUST UPDRAFTS CAPABLE OF PRODUCING MAINLY LARGE
HAIL WILL BE POSSIBLE IN THIS INITIAL ROUND OF THUNDERSTORMS LATE
SUNDAY MORNING INTO THE EARLY AFTERNOON. SOUTH OF THE AREA OF THE
MORNING THUNDERSTORMS THE BOUNDARY LAYER SHOULD BE ABLE TO
DESTABILIZE RAPIDLY THROUGHOUT THE DAY...SETTING THE STAGE FOR THE
MAIN PERIOD OF SEVERE THUNDERSTORMS.

MESOSCALE DETAILS WILL LIKELY NEED TO BE IRONED OUT THROUGHOUT THE
DAY TO DETERMINE THE TIMING AND STRENGTH OF THE STRONGEST STORMS FOR
THE AREA. 06Z RAP FORECAST OF SURFACE THETA E AND WIND DIRECTION
SHOWS A GOOD PUNCH OF DRY AIR COMING OFF THE SOUTHERN HIGH PLAINS
INTO THE WICHITA METRO AREA. THE EXACT LOCATION OF THIS DRY PUNCH
AND STRONG SURFACE WIND CONVERGENCE IS A LITTLE UNCERTAIN...BUT THAT
WOULD BE ONE OF THE FOCI FOR STORM DEVELOPMENT THIS AFTERNOON.
ANOTHER FACTOR IN FAVOR OF ROBUST CONVECTION ACROSS THE AREA IS THE
PRESENCE OF A VERY POTENT UPPER LEVEL JET...WHICH NOSES INTO SE
KANSAS...PUTTING THE CONVECTIVELY FAVORABLE LEFT EXIT REGION RIGHT
OVER THE FORECAST AREA. GIVEN THESE FACTORS IT APPEARS CONCEIVABLE
THAT A FEW STORMS WILL BE ABLE TO INITIATE 20-21Z IN THE
AFOREMENTIONED STRONG CONVERGENCE ZONE AND PUSH NORTHEAST UTILIZING
3500-4500 ML CAPE AND PERHAPS 40 TO 50 KTS OF DEEP LAYER SHEAR.
EXTREME MID LEVEL LAPSE RATES ON THE ORDER OF 9-9.5 C/KM WILL AID IN
CREATING THE EXTREME ML CAPE...SO ANY UPDRAFT THAT GOES UP DURING
PEAK HEATING WILL LIKELY BE ABLE TO PRODUCE LARGE HAIL...ON THE
ORDER OF BASEBALL SIZED...WITH PERHAPS SOME LARGER STONES. OF COURSE
WITH ANY STORM THAT BECOMES SURFACE BASED STRONG OUTFLOW WINDS WILL
ALWAYS BE PROBABLE...SO AREAS IN THE VICINITY OF THE STRONGEST
STORMS COULD SEE STRONG GUSTY WINDS ON THE ORDER OF 60 TO 70 MPH.
INITIAL STORM COVERAGE WILL LIKELY BE DICTATED BY DETAILED MESOSCALE
INFLUENCES AND COULD BE ISOLATED TO SCATTERED IN NATURE...HOWEVER
ONCE THE MAIN MID LEVEL SYSTEM CAN MOVE INTO THE AREA COVERAGE WILL
INCREASE...WITH DISCREET STORMS HAVING THE BEST CHANCE TO PRODUCE
LARGE HAIL...STRONG WINDS AND PERHAPS A TORNADO.

REGARDING THE TORNADO THREAT...GIVEN THE EXTREME INSTABILITY PRESENT
FOR THESE STORMS AND THE STRONG SHEAR IT CANNOT BE RULED OUT THAT A
TORNADO OR TWO COULD FORM. GIVEN THAT SURFACE WINDS WILL BE OUT OF
THE SSE AND LOW/MID LEVEL WINDS WILL BE VEERING WITH HEIGHT THE
GENERAL WIND SHEAR PROFILE WILL BE IN PLACE TO WARRANT A TORNADO
THREAT. FORECAST HODOGRAPHS FOR NUMEROUS STRONG TORNADOES ARE FAR
FROM PERFECT IN THIS SET UP...AS THE HODOGRAPHS LACK THE OPTIMAL
LOOPING CLOCKWISE STRUCTURE. WIND PROFILES DO LOOK A BIT BETTER WITH
THE LATEST RUNS OF THE MODELS THAN BEFORE...BUT STILL TAKE ON A BIT
OF AN S-SHAPE WITH COUNTERCLOCKWISE STRUCTURE. A PLANAR VIEW OF THE
LOW LEVEL WIND SHEAR SHOWS THAT ENOUGH TURNING WILL TAKE PLACE IN
THE LOWEST 1-3 KM TO CONTINUE A CONCERN FOR TORNADIC
BEHAVIOR...ESPECIALLY ONCE THE EARLY EVENING SETS IN AND THE LOW
LEVEL JET CAN INCREASE...LENGTHENING THE LOWEST LEVEL OF THE
HODOGRAPH. THE BOTTOM LINE IS THAT ALTHOUGH THE WIND SHEAR PROFILE
IS NOT PERFECT FOR STRONG TORNADOES TO OCCUR THERE IS ENOUGH OF A
SIGNAL FOR TORNADIC POTENTIAL TO WARRANT CONCERN FOR A DISCREET
STORM OR TWO TO PRODUCE A TORNADO...PERHAPS STRONG...ESPECIALLY IF A
BOUNDARY COMES INTO PLAY.

AS THE DAY WEARS ON STORM COVERAGE WILL LIKELY INCREASE AS THE MID
LEVEL TROUGH MOVES INTO THE AREA PROVIDING AMPLE ASCENT AND SUPPORT
FOR DEEP CONVECTION. ALSO MOVING THROUGH THE AREA IS A COLD FRONT
WHICH WILL ALSO AID IN INCREASING STORM COVERAGE AS IT PUSHES
THROUGH THE AREA. EXPECT A TRANSITION TO MCS/SQUALL LINE LATER IN
THE DAY AS STORMS INTERACT WITH EACH OTHER...EVENTUALLY CLEARING
THROUGH THE AREA OVERNIGHT SUNDAY NIGHT INTO MONDAY.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 330 AM CDT SUN MAY 19 2013

MON-TUES...HAVE KEPT LINGERING OVERNIGHT POPS WEIGHTED TOWARD THE
EAST AS WILL HAVE TO SEE HOW EVENING CONVECTION UNFOLDS SUNDAY.
LEAD RIPPLE IN THE BIGGER LONGWAVE TROF APPEARS TO MOVE NE INTO
IOWA BY 12Z MONDAY AND WOULD EXPECT SOME CLEARING FROM WEST TO
EAST BY MORNING. BRUNT OF THE LONGWAVE TROF STILL POISED TO THE
WEST OF THE AREA HOWEVER...AND JET STREAK ROUNDS THE BASE OVER
EASTERN KS BY THE NOON HOUR MONDAY. THIS HELPS KEEP THE FRONT OVER
SOUTHEAST KANSAS. BY 06Z TUESDAY...THE RRE OF THE UPPER JET AND
BROAD LIFT FROM THE UPPER TROF MOVE OUT OVER THE FRONT ONCE
AGAIN...AND FIRES OFF MORE STORMS OVER SOUTHEAST KANSAS. THESE
STORMS WOULD BE SEVERE AS GOOD INSTABILITY AND SHEAR REMAIN IN
PLACE. THE BEST FOCUS FOR SEVERE LOOKS TO BE JUST SE OF THE
TOPEKA COUNTIES WITH A SLIGHT RISK ACROSS THE SOUTHEAST HALF. SOME
DETAIL DEPENDS ON MORE MESOSCALE MECHANISMS AND FORECAST LOCATION
MAY ADJUST SOMEWHAT BETWEEN NOW AND MONDAY...BUT FOR THOSE ALONG
AND SE OF I35 STAY TUNED FOR POSSIBLY MORE SEVERE WEATHER LATE
MONDAY. PRECIP CHANCES DIMINISH AFTER SUNRISE TUESDAY AND POPS
REFLECT THIS TREND. HIGHS BY TUESDAY ONLY ANTICIPATED TO BE IN THE
70S AS COOLER TEMPS FROM THE NW OVERTAKE THE CENTRAL PLAINS.

WED-SAT ANTICIPATE COOLER THAN NORMAL HIGH TEMPERATURES AS UPPER
TROF IS SLOW TO MOVE OFF TO THE EAST AND SURFACE HIGH PRESSURE
PUSHES INTO THE PLAINS BEHIND THE SYSTEM INTO THE END OF THE WEEK.
SW FLOW REESTABLISHES OVER THE SW STATES...AND FRONT IN BETWEEN
GENERATES SHOWERS AND THUNDER AT TIMES OVER THE SOUTHEAST COUNTIES.
WILL CARRY SOME POPS A BIT HIGHER TO THE SW AS A RESULT. GENERALLY
ANTICIPATE DAYTIME HIGHS IN THE 70S WITH OVERNIGHT LOWS IN THE
50S.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 729 AM CDT SUN MAY 19 2013

EARLY MORNING SHOWERS SHOULD GIVE WAY TO A GRADUALLY CLEARING
SKY...ALTHOUGH THE STRATUS WILL BE TOUGH TO GET RID OF. EXPECT VFR
CONDITIONS DESPITE THE LIGHT RAIN THROUGH AT LEAST THIS AFTERNOON
BEFORE A ROUND OF SEVERE THUNDERSTORMS FORMS AROUND 20Z. EXPECT
THESE STORMS TO AFFECT THE TAF SITES THROUGH SUNSET BEFORE MOVING
EAST.

JL

&&

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

$$

SHORT TERM...LEIGHTON
LONG TERM...CRAVEN
AVIATION...LEIGHTON