Special Weather Statement, NWS Topeka, KS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
314 PM CDT TUE JUL 12 2011

.DISCUSSION...

TONIGHT THROUGH WEDNESDAY AFTERNOON...

19Z WATER VAPOR SHOWS A CLOSED UPPER-LEVEL TROUGH OVER
NORTHWEST OKLAHOMA WITH DECENT SOUTHERLY FLOW AT 500 MB STREAMING
COOLER AIR UPSTREAM INTO CENTRAL KANSAS. SURFACE ANALYSIS AND
VISIBLE SATELLITE SHOW INSTABILITY INCREASING AS DEVELOPING
TOWERING CU IS NOTED OVER SOUTH CENTRAL AND SOUTH EAST KANSAS
STREAMING NORTHWARD. WEAK FRONTAL BOUNDARY HAS SETTLED OVER NORTHERN
MISSOURI WESTWARD INTO NORTHERN KANSAS WHILE AN OUTFLOW BOUNDARY
FROM AN MCS OVER NEBRASKA WAS CONTINUING SOUTHEAST INTO MISSOURI.

CLOUD COVER SHOULD INCREASE THIS EVENING AS THE UPPER TROUGH
APPROACHES FROM THE SOUTHWEST. CHANCE POPS WERE INSERTED THIS
EVENING INTO THE OVERNIGHT PERIOD AS TWO SEPARATE LIFTING
MECHANISMS COME INTO PLAY. CONVERGENCE ALONG THE FRONTAL BOUNDARY
LIFTS NORTHWARD INTO SOUTHERN NEBRASKA WHILE AN UPPER DISTURBANCE
SHIFTS OVERHEAD. MOISTURE POOLING ALONG AND AHEAD OF THE BOUNDARY
SHOULD INCREASE DEW POINTS INTO THE LOWER 70S...PROVIDING THE
ADEQUATE MOISTURE AND ASCENT. HOWEVER...0-6 KM BULK SHEAR APPEARS
WEAK AT 20 KTS WHILE STRAIGHT UNIDIRECTIONAL FLOW AND ML CAPE QUITE
HIGH TO NEAR 3000 J/KG LATE AFTERNOON SUGGEST MULTI CELL STRUCTURE
WITH SUBSTANTIAL UPDRAFTS. THE 15Z EXPERIMENTAL HRRR AND 4KM WRF
MODELS ARE ALSO IN AGREEMENT...BEGINNING WITH ISOLATED CONVECTION
OVER SOUTH CENTRAL...INCREASING IN COVERAGE LATER THIS EVENING.
STRONG WINDS...SMALL HAIL AND HEAVY RAIN APPEAR TO BE THE MAIN
THREATS AT THIS TIME. LOWS OVERNIGHT IN THE 70S ARE PROGGED WITH
WINDS BECOMING LIGHT TOWARDS THE SOUTHEAST.

ON WEDNESDAY AFTERNOON...WEAK UPPER LEVEL FLOW WILL ALLOW THE
SHORTWAVE AND ASSOCIATED VORTICITY MAX TO STALL IN THE AREA.
CONTINUED CHANCE POPS AT THIS TIME WITH ISOLATED TO SCATTERED MULTI
CELL STORMS EXPECTED. A BRIEF RELIEF FROM THE HEAT IS EXPECTED WITH
CLOUD COVER AND ANY PRECIPITATION HOLDING TEMPERATURES TO THE LOWER
90S.

BOWEN

WEDNESDAY NIGHT THROUGH TUESDAY...

WEDNESDAY NIGHT AND THURSDAY...A MINOR UPPER LEVEL TROUGH WILL MOVE
AROUND THE NORTHERN PERIPHERY OF H5 RIDGE AXIS ACROSS THE SOUTHERN
PLAINS. THERE WILL BE ENOUGH ASCENT AHEAD OF THE H5 TROUGH ALONG
WITH WEAK ISENTROPIC LIFT TO CONTINUE A CHANCE FOR SHOWERS AND
THUNDERSTORMS WEDNESDAY NIGHT INTO THURSDAY MORNING. THE SOUTHERN
PLAINS UPPER LEVEL RIDGE WILL BEGIN TO AMPLIFY ACROSS THE CENTRAL
PLAINS. AFTERNOON HEATING MAY CAUSE ISOLATED THUNDERSTORMS TO
DEVELOP ACROSS THE CWA. I KEPT A SLIGHT CHANCE OF POPS IN THE
FORECAST GRIDS FOR THURSDAY AFTERNOON. HIGH TEMPERATURES WILL WARM
INTO THE MID TO UPPER 90S. HEAT INDICES WILL BE IN THE 98 TO 103
DEGREE RANGE.

FRIDAY THROUGH TUESDAY...WILL BE HOT. THE UPPER LEVEL RIDGE WILL
AMPLIFY AND CENTER ITSELF OVER NORTHEAST KS. THE ECMWF MODEL SHOWS
THE CENTER OF THE H5 RIDGE AXIS TO HAVE HEIGHTS OF 603 DKM AT 500MB
SATURDAY THROUGH TUESDAY. HIGH TEMPERATURES WILL REACH BETWEEN 99 TO
105 DEGREES ACROSS THE CWA. THE EASTERN AND NORTHERN COUNTIES MAY
KEEP LOWER TO MID 70 DEW POINTS...WHICH WOULD CAUSE HEAT INDICES TO
EXCEED 110 DEGREES EACH AFTERNOON. THE WESTERN AND SOUTHERN COUNTIES
MAY MIX DEEP ENOUGH FOR DEW POINTS TO DROP INTO THE MID TO UPPER 60S
DURING THE AFTERNOON HOURS. HOWEVER...MID TO UPPER 60S DEW POINTS
WHEN COMBINED WITH HIGH TEMPERATURES AROUND 103 DEGREES WOULD CAUSE
HEAT INDICES TO BE IN THE 104 TO 108 DEGREE RANGE. EXCESSIVE HEAT
WARNINGS OR HEAT ADVISORIES WILL MOST LIKELY BE NEEDED FRIDAY
THROUGH TUESDAY. I KEPT POPS THROUGH THIS PERIOD UNDER 14 PERCENT.

GARGAN

&&

.AVIATION...

PREDOMINANTLY VFR CONDITIONS EXPECTED THROUGH THE ENTIRE TAF
PERIOD. TOP/FOE LIGHT WINDS INITIALLY FROM NORTH WILL VARY AND
GRADUALLY TURN BACK AROUND TO SOUTHEAST. SCATTERED THUNDERSTORMS
ARE EXPECTED IN THE GENERAL VICINITY OF TAF SITES FROM 20Z THROUGH
04Z...BUT DUE TO EXPECTED SCATTERED NATURE HAVE KEPT CB GROUP FOR
THE TIME BEING. LOOK TO REMAIN DRY AFTER 06Z BUT THUNDERSTORMS IN
SOUTHERN KANSAS MAY KEEP CLOUDS IN THE AREA...PERHAPS FLIRTING
WITH MVFR AT TIMES.

BARJENBRUCH

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
EXCESSIVE HEAT WARNING UNTIL 8 PM CDT THIS EVENING FOR
KSZ010>012-022>024-026-035>040-054>056-058-059.

HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR KSZ008-009-020-021-
034.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TOPEKA KS
330 PM CDT TUE JUL 12 2011

KSZ008>012-020>024-026-034>040-054>056-058-059-132030-
REPUBLIC-WASHINGTON-MARSHALL-NEMAHA-BROWN-CLOUD-CLAY-RILEY-
POTTAWATOMIE-JACKSON-JEFFERSON-OTTAWA-DICKINSON-GEARY-MORRIS-
WABAUNSEE-SHAWNEE-DOUGLAS-LYON-OSAGE-FRANKLIN-COFFEY-ANDERSON-
330 PM CDT TUE JUL 12 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EAST CENTRAL...NORTH
CENTRAL AND NORTHEAST KANSAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

SCATTERED THUNDERSTORMS ARE EXPECTED THIS AFTERNOON AND OVERNIGHT.
SOME OF THE STRONGER THUNDERSTORMS MAY BE CAPABLE OF STRONG GUSTY
WINDS...FREQUENT LIGHTNING AND HEAVY RAIN.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

THERE IS A CHANCE FOR THUNDERSTORMS WEDNESDAY THROUGH THURSDAY.

A HEAT WAVE IS FORECAST TO CONTINUE FROM FRIDAY THROUGH TUESDAY
WITH HEAT INDICES FROM 105 TO 110 DEGREES EACH DAY. THE PROLONGED
PERIOD OF HEAT COULD BE DANGEROUS FOR THE ELDERLY AND THOSE
WITHOUT AIR CONDITIONING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED THROUGH TONIGHT.

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