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000
FXUS63 KTOP 151732
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1232 PM CDT WED MAY 15 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 331 AM CDT WED MAY 15 2013

THE FEATURE OF INTEREST FOR TODAY IS A WEAK CUT OFF MID LEVEL LOW
PRESSURE SYSTEM CURRENTLY SEEN ON WV IMAGERY OVER THE FAR WESTERN
TEXAS PANHANDLE. THIS SYSTEM WILL LIKELY KICK OFF A ROUND OF
THUNDERSTORMS WELL SOUTH OF THE FORECAST AREA TODAY...WHERE THE
BETTER MID LEVEL ASCENT IS LOCATED. AS THE DAY PROGRESSES AN AREA OF
LOW PRESSURE AT THE SURFACE WILL GRADUALLY DEEPEN...CONTINUING THE
WARM SOUTHERLY FLOW INTO THE FORECAST AREA. TO THE NORTHEAST OF THE
SURFACE LOW WINDS WILL BECOME MORE SOUTHEASTERLY...CREATING A BIT OF
A CONVERGENCE ZONE IN THE LOW LEVEL FLOW NORTH OF INTERSTATE 70.
ALTHOUGH THE TROUGH WILL BE WELL SOUTH OF THE FORECAST AREA IT MAY
PRODUCE A MEAGER AMOUNT OF LARGE SCALE ASCENT...HOWEVER IT LOOKS
LIKE THE MAIN FOCUS FOR LIFT WILL BE ASSOCIATED WITH THE WARM AIR
ADVECTION ISENTROPIC LIFT. WITH PLENTY OF INSTABILITY IN THE FORM OF
AROUND 2000 J/KG OF ML CAPE IN THE ATMOSPHERE IT LOOKS AS THOUGH A
FEW THUNDERSTORMS COULD FIRE ALONG THAT LOW LEVEL CONVERGENCE ZONE
ALONG OR NORTH OF INTERSTATE 70. THIS SOLUTION IS BACKED UP BY THE
06Z 12KM NAM AND 00Z 4KM WRF NMM...REGARDING TIMING LATER THIS
AFTERNOON/EVENING AND GENERAL AREA OF THUNDERSTORM ACTIVITY. WIND
SHEAR IS NOT SUPERB...AS DEEP LAYER SHEAR WILL ONLY LIKELY BE IN THE
20-30 KT RANGE...BUT WILL BE AMPLE TO PERHAPS CARRY ON SUSTAINED
UPDRAFTS. EXPECT ONLY AN ISOLATED HAIL AND WIND THREAT...ALONG WITH
THE POTENTIAL FOR MODERATE TO HEAVY RAIN WITH THE WEDNESDAY
AFTERNOON/EVENING THUNDERSTORMS POTENTIAL. EXPECT T-STORMS ACTIVITY
TO GRADUALLY WIND DOWN AFTER SUNSET...WITH PERHAPS SOME LINGERING
LIGHT TO MODERATE RAIN ONCE SURFACE HEATING SUBSIDES. GENERALLY
EXPECT OVERNIGHT LOWS TO BE CLOSE TO THE PREVIOUS NIGHT...WITH MIN
TEMPS IN THE MID 60S...HOWEVER AREAS WHERE CONVECTION OCCURS SOME
ENHANCED COOLING MAY OCCUR OVERNIGHT CAUSING MIN TEMPS TO BE A BIT
LOWER THAN FORECAST.

JL

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 331 AM CDT WED MAY 15 2013

THURSDAY THROUGH FRIDAY NIGHT...AN UPPER LEVEL TROUGH WILL MOVE INTO
THE WESTERN US AND SLOWLY MOVE EAST INTO THE FOUR CORNERS REGION. A
DOWNSTREAM UPPER RIDGE WILL AMPLIFY ACROSS THE PLAINS AND SLOWLY
SHIFT EAST INTO THE MID AND UPPER MS RIVER VALLEY. A LEE SURFACE
TROUGH WILL DEEPEN ACROSS WESTERN KS...ALLOWING THE LOW-LEVEL
SOUTHERLY FLOW TO ADVECT DEEPER GULF MOISTURE NORTHWARD ACROSS THE
PLAINS. AN EML WILL OVERSPREAD MUCH OF THE SOUTHERN AND CENTRAL
PLAINS...THUS THE CAP STRENGTH SHOULD KEEP MUCH OF THE AREA DRY
THROUGH THE PERIOD. STORMS MAY DEVELOP ALONG THE SURFACE DRYLINE
ACROSS WESTERN NE AND WESTERN KS. THESE STORMS SHOULD DISSIPATE AS
THEY MOVE EAST INTO WEST CENTRAL KS AND THE SURFACE DRYLINE RETREATS
DURING THE EVENING HOURS.

HIGH TEMPERATURES WILL REACH THE LOWER TO MID 80S...THOUGH IT MAY
FEEL WARMER DUE TO THE DEEPER MOISTURE IN PLACE.

SATURDAY AND SATURDAY NIGHT...THE UPPER LEVEL TROUGH WILL MOVE EAST
FROM THE FOUR CORNERS REGION INTO SOUTHEAST CO AND THE TX PANHANDLE.
THIS WILL CAUSE THE DRYLINE TO MOVE FARTHER EAST INTO WEST CENTRAL
AND CENTRAL KS DURING THE AFTERNOON HOURS. THE CAP MAY BE TOO
STRONG FOR THUNDERSTORMS TO DEVELOP ALONG THE DRYLINE...THOUGH IF
THERE IS ENOUGH SURFACE CONVERGENCE...PLUS ASCENT AHEAD OF THE H5
TROUGH...THE CAP MAY BREAK FOR ISOLATED THUNDERSTORMS TO DEVELOP
ACROSS NORTH CENTRAL AND CENTRAL KS...JUST WEST OF THE CWA. GIVEN
ML CAPES OF AROUND 2,000-2,500 AND SFC TO 6 KM BULK SHEAR OF 30 TO
40 KTS...THESE THUNDERSTORMS MAY EVOLVE INTO SUPERCELL
THUNDERSTORMS AND MAY PRODUCE LARGE HAIL AND DAMMING WIND GUSTS.
IT IS TOO EARLY TO ASSESS THE LOW-LEVEL VERTICAL WIND SHEAR AND ANY
TORNADO POTENTIAL. DURING THE EVENING HOURS THESE ISOLATED TO
SCATTERED SEVERE THUNDERSTORMS MAY MOVE INTO THE WESTERN COUNTIES
OF THE CWA AND MAY PRODUCE LARGE HAIL AND DAMAGING WIND GUSTS. AS
THE SURFACE TEMPERATURE COOLS AND A LOW-LEVEL INVERSION SETS UP
ACROSS THE CWA...ANY SEVERE THUNDERSTORMS LATER IN THE EVENING AND
THROUGH THE EARLY MORNING HOURS OF SUNDAY SHOULD BE ELEVATED WITH
ONLY THE RISK OF LARGE HAIL WITH THE STRONGER THUNDERSTORMS. HIGHS
ON SATURDAY SHOULD REACH THE MID TO UPPER 80S.

SUNDAY...THE H5 TROUGH WILL LIFT NORTHEAST ACROSS EASTERN KS DURING
THE DAY. A COLD FRONT WILL PUSH SOUTHEAST ACROSS THE CWA DURING THE
AFTERNOON HOURS AND NUMEROUS SHOWERS AND THUNDERSTORMS WILL DEVELOP
ALONG AND NORTH OF THE COLD FRONT. THE STORMS MAY EVOLVE INTO A
SQUALL LINE ALONG THE SURFACE COLD FRONT...ACROSS NORTHEAST AND
EAST CENTRAL KS...DURING THE LATE AFTERNOON AND EVENING HOURS.
ML CAPES AHEAD OF THE COLD FRONT WILL INCREASE TO AROUND 2,000 J/KG
AND THE SFC TO 6KM SHEAR WILL BE 30 TO 40 KTS...THUS ORGANIZED
SEVERE THUNDERSTORMS WILL BE POSSIBLE...SOME MAY BE SUPERCELL
THUNDERSTORMS BEFORE CONGEALING INTO A SQUALL LINE. THE LOW-LEVEL
WINDS WILL VEER AHEAD OF THE COLD FRONT...THUS I THINK THE TORNADO
POTENTIAL WILL BE LOW ACROSS EASTERN KS. ANY ROTATING STORM WILL
BE CAPABLE OF PRODUCING LARGE HAIL AND DAMAGING WIND GUSTS...AND
THE STRONG OUTFLOW WINDS MAY BECOME MORE OF A THREAT IF A SQUALL
LINE DEVELOPS.

SUNDAY NIGHT THROUGH MONDAY NIGHT...ANOTHER H5 TROUGH WILL FOLLOW
QUICKLY BEHIND THE H5 TROUGH LIFTING NORTHEAST OUT OF EASTERN
KS/EASTERN NE INTO THE UPPER MIDWEST. THE SECOND H5 TROUGH WILL
CAUSE 850MB WINDS TO BACK MORE TO THE SOUTH. DEEP GULF MOISTURE WILL
ADVECT NORTHWARD OVER THE SFC FRONT THAT WILL BECOME STATIONARY
ACROSS EXTREME SOUTHEAST KS. THE RESULTING ISENTROPIC LIFT WILL
KEEP A GOOD CHANCE FOR SHOWERS AND ELEVATED THUNDERSTORMS ACROSS
MUCH OF THE CWA LATE SUNDAY NIGHT INTO MONDAY EVENING. STRONGER
ASCENT AHEAD THE H5 TROUGH MOVING EASTWARD ACROSS THE SOUTHERN PLAINS.
THIS SECONDARY H5 TROUGH WILL PHASE WITH THE LEAD H5 TROUGH OVER
THE MIDWEST TO PRODUCE ONE AMPLIFIED H5 TROUGH FROM THE UPPER
MIDWEST INTO EAST TX. THE PHASED H5 TROUGH AXIS WILL SHIFT EAST OF
THE CWA LATE MONDAY EVENING AND MOST OF THE RAIN AND THUNDERSTORMS
WILL SHIFT EAST OF THE CWA. DURING THE DAY MONDAY THERE MAY BE
ENOUGH ELEVATED CAPE COMBINED WITH STRONG VERTICAL WIND SHEAR FOR
SOME ELEVATED ROTATING STORMS WHICH MAY PRODUCE LARGE HAIL ACROSS
EAST CENTRAL KS LATE SUNDAY NIGHT THROUGH MONDAY EVENING. WE MAY
ALSO SEE SOME HEAVIER RAINFALL THROUGH THIS PERIOD AS WELL. HIGHS
WILL COOL INTO THE MID TO UPPER 70S ON MONDAY WITH PERIODS OF RAIN
AND THUNDERSTORMS POSSIBLE.

TUESDAY...A SURFACE RIDE OF HIGH PRESSURE WILL BUILD SOUTHWARD
ACROSS EASTERN KS. SKIES WILL BE MOSTLY SUNNY BUT HIGH TEMPERATURES
WILL ONLY REACH THE LOWER TO MID 70S.

GARGAN

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1227 PM CDT WED MAY 15 2013

CHANCES FOR CONVECTION AT THE TERMINALS ARE FALLING WITH BOUNDARY
STAYING NORTH...AND FEEL CONFIDENT ENOUGH TO REMOVE INCLUSION. MAY
SEE GUSTS NEAR 20KT THROUGH THE NEXT FEW HOURS BUT THINK THEY WILL
BE THE EXCEPTION. LOW LEVEL MOISTURE STILL ON TRACK TO INCREASE
TONIGHT...WITH LOWER VISIBILITIES AND PERHAPS CEILINGS AS WELL
DEVELOPING. WILL KEEP MVFR FORECAST AT THIS POINT BUT FURTHER
RESTRICTIONS ARE POSSIBLE.

&&

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

$$

SHORT TERM...LEIGHTON
LONG TERM...GARGAN
AVIATION...65