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000
FXUS63 KTOP 211129
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
629 AM CDT TUE MAY 21 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 314 AM CDT TUE MAY 21 2013

VERTICALLY STACKED SYSTEM REMAINS OVER THE NORTHERN PLAINS WITH AN
OBVIOUS UPPER WAVE TURNING EAST FROM NEW MEXICO IN THE CYCLONIC
FLOW. A WEAK COLD FRONT WAS JUST EAST OF KANSAS AT 08Z.

MAIN CONCERN TODAY IS THE TRACK OF THE SOUTHERN PLAINS WAVE AND ITS
IMPACT ON LOW LEVEL WIND FIELDS AND THUS PRECIPITATION CHANCES.
MODELS ARE IN GOOD AGREEMENT WITH BEST POTENTIAL VORTICITY ADVECTION
AND Q-VECTOR CONVERGENCE REMAINING SOUTH OF THE COUNTY WARNING
AREA...THOUGH SEVERAL SMALLER RESOLUTION MODELS BACK LOW LEVEL WINDS
OVER SOUTHEAST KANSAS WITH SLOW MOVEMENT TO THE SYNOPTIC SYSTEM. IF
THIS TAKES PLACE...WEAK INSTABILITY AND CONVERGENCE NEAR THE
BOUNDARY COULD BE ENOUGH FOR A FEW THUNDERSTORMS TO DEVELOP LATE
THIS AFTERNOON INTO THE EARLY EVENING. THE BOUNDARY SHOULD EXIT BY
LATE EVENING WITH STABILIZING CONDITIONS ALLOWING FOR A MAINLY DRY
NIGHT. HIGHS TODAY SHOULD BE SEVERAL DEGREES COOLER THAN MONDAY
BEHIND THE FIRST FRONT. THE STACKED SYSTEM TRANSLATES EAST-SOUTHEAST
TONIGHT FOR SOME INCREASE IN CLOUDS ROTATING IN BEHIND.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 314 AM CDT TUE MAY 21 2013

WED-THURS...COOL HIGH PRESSURE CONTINUES TO FILTER INTO THE
CENTRAL PLAINS BEHIND THE SLOWLY DEPARTING TROF ACROSS THE GREAT
LAKES. THINK WE WILL SEE ENOUGH INSOLATION AS CLOUDS MOVE EAST AT
LEAST ACROSS SOUTHWESTERN COUNTIES...AND HAVE MID 70S WEST WITH
60S IN THE NE WHERE CLOUDS ARE LATE TO PART. LOWS IN THE UPPER 40S
NW WITH LOWER 50S SE AS SKIES CLEAR AND WINDS LIGHTEN OVERNIGHT.
MORE SUNSHINE ON THURSDAY SHOULD BOOST HIGHS INTO THE LOWER/MIDDLE
70S MOST AREAS. BY THURSDAY EVENING...UPPER SHORTWAVE RIDGE
BETWEEN SYSTEMS STARTS TO MOVE EASTWARD WITH SW FLOW OVER THE
FRONT ACROSS THE HIGH PLAINS...MAY SEND SOME SHOWERS/TS INTO THE
FAR WESTERN COUNTIES OVERNIGHT AS LLJ INCREASES.

FRI/SAT...BOTH EC AND GFS SEND A LEAD WAVE AROUND THE WESTERN
TROF OUT INTO THE NORTHERN ROCKIES ON FRIDAY...WHICH IN TURN HELPS
GET RETURN FLOW REESTABLISHED OVER THE HIGH PLAINS. SOME QPF
DEPICTED ACROSS THE FA FOR FRIDAY DURING THE DAY BUT THINK COULD
BE A LITTLE OVERDONE. GFS SFC LOW DEVELOPS OVER THE NE/CO BORDER
WITH WARM FRONT EXTENDING EASTWARD ACROSS NEBRASKA...AND APPEARS
TO BE THE FOCUS FOR CONVECTION DEVELOPING AS SHORTWAVES RIDE
ACROSS THE BOUNDARY OUT OF THE HIGH PLAINS. EC IS A BIT STRONGER
AND FASTER WITH THE WAVE...AS WELL AS A BIT FARTHER SOUTHWARD WITH
THE FRONTAL BOUNDARY AND THEREFORE BRINGS MORE PRECIP INTO OUR
AREA. RETURN OF THE LOW LEVEL MOISTURE BRINGS A GRADUAL INCREASE
IN INSTABILITY...WITH CAPE VALUES BACK INTO THE 2000J/KG AND
GREATER RANGE BY SATURDAY AFTERNOON. FLOW ALOFT HOWEVER IS
STRONGER TO THE NORTH...WHERE BULK SHEAR VALUES ARE A BIT HIGHER.
CORFIDI VECTORS SUGGEST STORMS COULD FORM IN THE HIGH PLAINS AND
MOVE INTO OUR AREA ON SATURDAY...AND WILL CARRY HIGHER POPS THIS
TIME PERIOD FOR SUCH.

SUN/MON FORECAST WILL DEPEND ON HOW STRONG THE SOUTHWESTERLY FLOW
CAN BECOME TO OUR WEST. IF GFS IS CORRECT THEN FRONTAL PATTERN
SHIFTS BACK TO THE NORTH...WHILE THE NEW EC KEEPS THE BOUNDARY
OVER KANSAS AND THEREFORE MORE PRECIPITATION CHANCES THIS PERIOD.
WILL KEEP TREND OF DAILY POPS WITH SLIGHTLY HIGHER VALUES
OVERNIGHT WHEN LLJ COMES INTO PLAY. 67

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 629 AM CDT TUE MAY 21 2013

VFR CONDITIONS ARE ANTICIPATED. WEST WINDS BEHIND A COLD FRONT
WILL BE THE RULE THROUGH MUCH OF THE FORECAST. SCATTERED CUMULUS
MAY DEVELOP IN THE 18Z-23Z PERIOD BUT WILL BE WELL ABOVE 3000FT.

65

&&

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

$$

SHORT TERM...65
LONG TERM...67
AVIATION...65