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000
FXUS63 KTOP 182340
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
640 PM CDT SAT MAY 18 2013

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 344 PM CDT SAT MAY 18 2013

AT MID AFTERNOON WELL DEFINED DRYLINE EXTENDED FROM WESTERN KS INTO
NORTHWEST OK...WITH TOWERING CU RAPIDLY DEVELOPING ALONG IT AHEAD OF
A STRONG SHORTWAVE TROUGH MOVING INTO THE OK/TX PANHANDLES.
THUNDERSTORMS IN THIS AREA WILL INTENSIFY INTO THE EVENING HOURS.
MODELS DIFFER SIGNIFICANTLY ON HOW THEY HANDLE THE EVOLUTION OF THE
WESTERN/CENTRAL KS CONVECTION THIS EVENING AS IT SPREADS EAST AND
NORTHEAST OFF THE DRYLINE. CURRENT FCST REFLECTS A MODEL CONSENSUS
FAVORING A GRADUAL AREAL DECREASE OF BROKEN LINE/QLCS THAT ENTERS
INTO THE WESTERN COUNTY WARNING AREA BY MIDNIGHT THEN FURTHER
WEAKENING EASTWARD ACROSS THE REMAINDER OF THE CWA AS STRONG CAPPING
INVERSION AND LESS FAVORABLE SHEAR PROFILES ARE ENCOUNTERED. ONE
OFFSETTING FACTOR WILL BE THE POTENTIAL FOR SOME UPSCALE GROWTH FOR
ELEVATED CONVECTION WITH AN INCREASING BUT SLOWLY VEERING LOW LEVEL
JET LATE IN THE EVENING AND OVERNIGHT. WILL FAVOR THE WEST AND
NORTHWEST CWA THIS EVENING THEN THE NORTHEAST AND EAST CENTRAL
COUNTIES LATER IN THE NIGHT. THE MAIN LOW END POTENTIAL FOR EVENING
CONVECTION IN THE EASTERN COUNTIES WILL BE MAINLY FROM THE PASSAGE
OF A WEAK MCV LIFTING NORTHEAST ACROSS THE AREA AND LLVL JET LATER
ON. MAIN SEVERE POTENTIAL TONIGHT WILL BE THE POTENTIAL FOR HAIL TO
ONE INCH AND STRONG GUSTY WINDS NORTH AND WEST OF THE TURNPIKE.

A MORE WIDESPREAD AND MORE SIGNIFICANT THREAT FOR SEVERE WEATHER
STILL EXPECTED FOR SUNDAY. STRONG SHORTWAVE TROUGH NOW OVER UT WILL
SWING RAPIDLY OUT OF THE TX PANHANDLE EARLY SUNDAY MORNING AND
ACROSS THE CWA THROUGH THE AFTERNOON. THEREFORE...AFTER A TEMPORARY
BREAK/WEAKENING TREND OF ANY REMAINING CONVECTION IN THE MORNING
FROM THE OVERNIGHT HOURS...THERE REMAINS THE LIKELIHOOD THAT STRONG
TO SEVERE THUNDERSTORMS WILL REFORM IN THE AFTERNOON. THIS SHOULD
OCCUR AS VERY STEEP LAPSE RATES DEVELOP OVER THE CWA WITH THE
APPROACH OF THE SHORTWAVE TROUGH WHICH WILL MAKE WAY FOR CAPE VALUES
COMMONLY IN THE RANGE OF 2500-3500 J/KG PRIMARILY ACROSS NORTHEAST
AND EAST CENTRAL AREAS AFTER 2 PM...THEN SPREADING EASTWARD ACROSS
THE REMAINDER OF THE CWA THROUGH THE AFTERNOON. HAVE REFLECTED THIS
SCENARIO IN THE GRIDS WITH LIKELY POPS AND THE MENTION OF SEVERE
POTENTIAL. EXPECT VERY LARGE HAIL AND STRONG WINDS TO BE THE MAIN
SEVERE THREATS ALONG WITH ISOLATED TORNADOES...ESPECIALLY IF ANY
SUSTAINED DISCRETE SUPERCELLS OCCUR. DESPITE THE CLOUDS...STILL
EXPECT HIGHS TO MAKE NEAR 80 IN THE NORTH CENTRAL TO THE MIDDLE 80S
ELSEWHERE.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 344 PM CDT SAT MAY 18 2013

EXPECT ONGOING STRONG TO SEVERE CONVECTION SUNDAY EVENING AS THE
NEGATIVE TILT MID LEVEL TROUGH PROGRESSES EAST NORTHEAST ACROSS
EASTERN KANSAS. SEVERE THREAT WILL CONTINUE THROUGH 06Z IN EAST
CENTRAL KANSAS. VERY LARGE HAIL WILL BE THE PRIMARY HAZARD AND
ISOLATED TORNADOES WILL BE POSSIBLE THROUGH THE EVENING HOURS.
STRONG WINDS ARE ALSO POSSIBLE ACROSS EASTERN KANSAS WITH STORMS
BECOMING LINEAR MOVING EAST.

MONDAY STILL A BIT OF A QUESTION MARK WITH THE PLACEMENT OF THE
FRONTAL BOUNDARY/SURFACE TROUGH ACROSS EAST CENTRAL OR SOUTHEAST
KANSAS. AT THIS TIME WILL GO WITH THE BOUNDARY IN OR NEAR EAST
CENTRAL KANSAS. SOME STRONG TO SEVERE STORMS WILL BE POSSIBLE
ACROSS EAST CENTRAL KANSAS MONDAY AFTERNOON AND EVENING MAINLY
ALONG AND SOUTHEAST OF I-35.

A CLOSED UPPER LOW WILL SPIN OVER THE NORTHERN PLAINS THROUGH
WEDNESDAY WITH RIDGING OVER THE CENTRAL PLAINS THURSDAY AND
CONTINUING TO BUILD THROUGH SATURDAY. WITH THE SLOW MOVEMENT OF THE
UPPER LOW AND LOBES ROTATING AROUND IT THERE REMAINS A CHANCE OR
SLIGHT CHANCE OF THUNDERSTORMS TUESDAY BUT THEN ACROSS THE NORTHERN
COUNTIES NEAR THE NEBRASKA BORDER TUESDAY NIGHT AND WEDNESDAY.
NOCTURNAL AND EARLY MORNING THUNDERSTORMS WILL BE POSSIBLE FROM
THURSDAY NIGHT INTO SATURDAY. TEMPERATURES WILL BE COOLER FOR THE
WEEK WITH HIGHS IN THE 70S AND LOWS IN THE 50S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 640 PM CDT SAT MAY 18 2013

CONFIDENCE IN FORECAST DETAILS AND TIMING IS LOW DUE TO SEVERAL
DIFFERING MODEL SOLUTIONS. CONTINUED WITH THE PREVIOUS FORECAST
IDEA OF SOME ELEVATED STORMS POSSIBLY MOVING THROUGH THE AREA LATE
TONIGHT. IF THIS OCCURS...THERE COULD BE SOME MVFR CIGS DEVELOP
BEFORE SUNRISE. THINK VFR CONDITIONS ARE LIKELY BY LATE MORNING AS
MIXING INCREASES WITH A STRENGTHENING PRESSURE GRADIENT. THEN
STORM STORM DEVELOPMENT SUNDAY AFTERNOON APPEARS TO BE RELATIVELY
EARLY IN THE DAY WITH GOOD DYNAMICS OVERSPREADING A VERY UNSTABLE
AIRMASS. TAFS ARE A BEST GUESS AT TIMING WITH ADJUSTMENTS LIKELY
AS THINGS UNFOLD.

&&

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

&&

$$

SHORT TERM...63
LONG TERM...53
AVIATION...WOLTERS