000
FXUS63 KTOP 161738
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1238 PM CDT THU MAY 16 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 339 AM CDT THU MAY 16 2013

WATER VAPOR IMAGERY AROUND 08Z INDICATES THE CLOSED LOW STILL
SPINNING CYCLONICALLY ACROSS CENTRAL OKLAHOMA...WITH THE FORECAST
AREA TO THE NORTH OF ANY REAL EFFECTS FROM THIS SLOWLY PROGRESSING
LOW PRESSURE SYSTEM. AT THE SURFACE CALM WINDS AND GOOD RADIATIONAL
COOLING UNDER CLEAR SKIES HAS ALLOWED FOR SOME PATCHY FOG TO
DEVELOP. AREAS WHERE CLOUDS ARE LOCATED SURFACE TEMPS HAVE NOT
COOLED AS MUCH...MITIGATING THE FOG. TO THE SOUTH SATELLITE
OBSERVATIONS SHOW AN AREA OF STRATUS ALONG THE NORTHERN PERIPHERY OF
THE AFOREMENTIONED MID LEVEL LOW. THIS STRATUS DECK MAY WORK ITS WAY
INTO THE SOUTHERN HALF OF THE FORECAST AREA THIS MORNING...HOWEVER
EXPECT PATCHY MORNING FOG AND LOW STRATUS TO WEAR OFF THIS MORNING
JUST AFTER SUNRISE AS THE BOUNDARY LAYER BEGINS TO WARM AND MIX A
BIT. SOUTHEAST WINDS WILL THEN RECOMMENCE AROUND 5 TO 10 KTS KEEPING
WARM AND MOIST AIR ADVECTING INTO THE FORECAST AREA. EXPECT HIGHS
TODAY TO BE A BIT CLOSER TO NORMAL THAN THE PREVIOUS COUPLE DAYS AS
MAX TEMPS WILL LIKELY BE IN THE LOWER TO MID 80S. SHORT RANGE
CONVECTIVE ALLOWING MODELS HINT AT A COUPLE AREAS OF
AFTERNOON/EVENING CONVECTION THAT MAY IMPACT THE FORECAST AREA. THE
FIRST AREA OF INTEREST IS ACROSS FAR SE KANSAS AND SW
MISSOURI...WHERE SOME MEAGER ISENTROPIC LIFT MAY BRING A FEW
SHOWERS. EXPECT THAT ACTIVITY TO REMAIN SOUTH OF THE FORECAST AREA.
THE OTHER AREA OF INTEREST IS ACROSS THE NW ZONES (NC
KANSAS)...WHERE THE HIGHER RESOLUTION NAM INDICATES A WEAK SHORTWAVE
TROUGH GLIDING THROUGH CENTRAL NEBRASKA. OVERALL EXPECT THAT
ACTIVITY TO REMAIN NORTH OF THE FORECAST AREA...BUT KEPT A SLIGHT
CHANCE OF POPS ACROSS THE FAR NW ZONES FOR THIS EVENING. MAINLY
PERSISTENCE FORECAST FOR OVERNIGHT LOWS...AS LITTLE CHANGE IN
AIRMASS OR CONDITIONS ARE EXPECTED TO AFFECT THE AREA.

JL

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 339 AM CDT THU MAY 16 2013

FRIDAY THROUGH SATURDAY MORNING...AN UPPER LEVEL TROUGH WILL MOVE
EASTWARD FROM THE WEST COAST INTO THE FOUR CORNERS REGION SATURDAY
AFTERNOON. A DOWNSTREAM UPPER LEVEL RIDGE WILL AMPLIFY ACROSS THE
PLAINS ON FRIDAY AND SLOWLY SHIFT EASTWARD INTO THE MS RIVER VALLEY
SATURDAY NIGHT. A LEE SURFACE TROUGH WILL DEEPEN ACROSS THE CENTRAL
AND SOUTHERN HIGH PLAINS. THE SOUTHERLY LOW LEVEL FLOW EAST OF THE
LEE SURFACE TROUGH WILL CAUSE DEEP GULF MOISTURE TO ADVECT
NORTHWARD ACROSS THE SOUTHERN AND CENTRAL PLAINS. AN ELEVATED MIXED
LAYER WILL OVER SPREAD THE CENTRAL AND SOUTHERN PLAINS...CAUSING A
STRONG CAP TO DEVELOP THAT WILL INHIBIT ANY DEEP MOIST CONVECTION
FROM DEVELOPING. ANY THUNDERSTORMS WILL OCCUR ALONG THE DRYLINE FROM
THE TX PNHDL...NORTHWARD ACROSS WESTERN KS INTO WESTERN NE AND SD
THROUGH THE PERIOD. HIGHS WILL BE IN THE LOWER TO MID 80S.

SATURDAY AFTERNOON AND SATURDAY NIGHT...THE UPPER TROUGH WILL BEGIN
TO LIFT NORTHEAST ACROSS NM AND CO AND THE DRYLINE MAY MOVE EAST
INTO WEST CENTRAL KS. ISOLATED SUPERCELLS THAT DEVELOP ALONG THE
DRYLINE MAY PRODUCE LARGE HAIL AND DAMAGING WIND GUSTS...BUT THESE
STORMS WILL PROBABLY WEAKEN AND DISSIPATE BEFORE MOVING INTO THE
WESTERN COUNTIES OF THE CWA LATE SATURDAY NIGHT. HIGHS WILL REACH
THE MID TO UPPER 80S.

SUNDAY AND SUNDAY NIGHT...THE UPPER LEVEL TROUGH WILL LIFT OUT WITH
A NEGATIVE TILT ACROSS NE/KS/NORTHERN OK. THE SURFACE DRYLINE WILL
PUSH EAST INTO THE WESTERN COUNTIES OF THE CWA DURING THE AFTERNOON
HOURS. SURFACE CONVERGENCE ALONG THE DRYLINE...ALONG WITH ASCENT
AHEAD OF THE APPROACHING H5 TROUGH SHOULD CAUSE SCATTERED
THUNDERSTORMS TO DEVELOP. THE ECMWF SHOWS AN ENVIRONMENT CONDUCIVE
FOR SUPERCELL THUNDERSTORM DEVELOPMENT ACROSS EASTERN KS. THE ECMWF
FORECAST MLCAPE TO RANGE FROM 2500 TO 3500 J/KG AND ADEQUATE
VERTICAL WIND SHEAR FOR ORGANIZED SEVERE THUNDERSTORMS...WITH SOME
SUPERCELL THUNDERSTORMS POSSIBLE. IT IS TOO EARLY TO DETERMINE THE
TORNADO THREAT...BUT ANY SUPERCELL THUNDERSTORM WILL BE CAPABLE OF
PRODUCING LARGE HAIL AND DAMAGING OUTFLOW WINDS...ALONG WITH
ISOLATED TORNADOES. THE DRYLINE WILL PUSH EAST ACROSS THE CWA DURING
THE AFTERNOON AND EARLY EVENING HOURS. WE MAY SEE A BREAK IN THE
THUNDERSTORMS THROUGH THE MID EVENING HOURS INTO THE EARLY MORNING
HOURS OF MONDAY. HIGHS WILL BE IN THE MID 80S...WITH SOME UPPER 80S
OR 90 DEGREE READINGS BEHIND THE DRYLINE ACROSS THE SOUTHWEST
COUNTIES DURING THE LATE AFTERNOON HOURS OF SUNDAY.

MONDAY AND MONDAY NIGHT...A SECOND UPPER LEVEL TROUGH WILL MOVE
EAST...DIRECTLY BEHIND THE FIRST UPPER THROUGH THAT WILL LIFT
NORTHEAST INTO SOUTHEAST SD. THE SECOND H5 TROUGH WILL BEGIN TO
PHASE WITH LEAD NORTHERN H5 TROUGH AND TURN INTO A SINGLE HIGH
AMPLITUDE UPPER LEVEL TROUGH ACROSS THE EASTERN PLAINS AND UPPER
MIDWEST. MONDAY...A COLD FRONT WILL PUSH EAST ACROSS THE CWA. DEEP
MOISTURE WILL RAPIDLY MOVE BACK NORTHWARD ACROSS EASTERN KS AHEAD OF
THE COLD FRONT DURING THE MORNING HOURS. THUNDERSTORMS WILL ONCE
AGAIN DEVELOP ALONG THE SURFACE COLD FRONT ALONG THE WESTERN
COUNTIES OF THE CWA AND EXPAND EASTWARD DURING THE AFTERNOON HOURS.
INITIALLY STORMS THAT GO UP ALONG THE FRONT MAY EVOLVE INTO
SCATTERED SUPERCELL THUNDERSTORMS...BUT THE FORCING ALONG THE FRONT
LOOKS TO BE LINEAR AND MOST LIKELY A SQUALL LINE WILL RAPIDLY FORM
ACROSS NORTHEAST AND EAST CENTRAL KS DURING THE MID AND LATE
AFTERNOON HOURS. THE LOW-LEVEL WINDS WILL BE VEERED AHEAD OF THE
FRONT...SO THE PROBABILITY OF TORNADOES WILL BE RATHER LOW. THOUGH
THE STRONGER ROTATING UPDRAFTS EMBEDDED IN A SQUALL LINE MAY PRODUCE
LARGE HAIL AND DAMAGING WIND GUSTS. THE LINE OF STRONG TO SEVERE
THUNDERSTORMS WILL PUSH SOUTHEAST OF THE CWA DURING THE MID AND LATE
EVENING HOURS. THERE ALSO MAY BE SOME HEAVY RAINFALL ACROSS EAST
CENTRAL KS...IF A SLOW MOVING LINE OF THUNDERSTORMS DEVELOPS.

TUESDAY AND WEDNESDAY...THE H5 TROUGH AXIS WILL PUSH EAST INTO THE
MIDWEST AND MS RIVER VALLEY. NORTHWEST SURFACE WINDS BEHIND THE
FRONT WILL CAUSE TEMPERATURES TO BE COOLER WITH HIGHS IN THE LOWER
TO MID 70S.

GARGAN

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1238 PM CDT THU MAY 16 2013

VFR CONDITIONS WILL DOMINATE THROUGH AT LEAST 03Z...BUT
DETERIORATING CONDITIONS SHOULD TAKE PLACE BY 10Z IN MOIST LOW
LEVELS AND LIGHT WINDS. AT THIS POINT DETAILS IN A CIG OR VIS
ISSUE ARE UNCERTAIN...AND MUCH WILL DEPEND ON SMALL SCALE TRENDS
AS THIS PERIOD NEARS...BUT IFR EITHER WAY SEEMS QUITE LIKELY.
IMPROVING CONDITIONS SHOULD TAKE PLACE BY 15Z.

&&

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

$$

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