Severe Thunderstorm Warning 183, NWS Topeka, KS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
347 PM CDT MON JUL 20 2009

.DISCUSSION...

TONIGHT...PARAMETERS COMING TOGETHER FOR A POTENTIAL HEAVY RAINFALL
EVENT ACROSS NORTHEAST AND EAST CENTRAL KANSAS. CURRENT 3 HOUR FFG
VALUES GENERALLY RUNNING AROUND TWO INCHES OR LESS NORTH OF
INTERSTATE 70 AND INTO PARTS OF FRANKLIN COUNTY.

RADAR LOOPS THIS AFTERNOON SHOW AN MCV CURRENTLY JUST TO THE
SOUTHEAST OF THE TOPEKA RDA WHICH WAS HELPING TO MAINTAIN AN AREA OF
SHOWERS AND ISOLATED THUNDERSTORMS ACROSS NORTHEAST AND EAST CENTRAL
KANSAS. LATEST MESO ANALYSIS HAD PRECIPITABLE WATER VALUES IN THE
1.5 TO 2 INCH RANGE ACROSS MUCH OF THE CWA. 850 MB MOISTURE
TRANSPORT WAS INCREASING MOISTURE INTO NORTH CENTRAL AND NORTHEAST
KANSAS THIS AFTERNOON. MUCH OF THE EASTERN TWO THIRDS OF THE CWA
HAVE REMAINED RELATIVELY STABLE THIS AFTERNOON WITH CAPES OF 200 TO
500 J/KG. IN AREAS OF CENTRAL KANSAS EASTWARD INTO THE WESTERN
COUNTIES OF THE CWA MUCAPES WERE IN THE 1000 TO 1500 J/KG RANGE.

FOR TONIGHT...MODELS ALL BULLSEYE PARTS OF NORTHEAST AND EAST
CENTRAL KANSAS WITH HEAVY RAINFALL. MAINLY WENT WITH A COMBINATION
OF THE NAM...UKMET AND ECMWF FOR THE RAINFALL POTENTIAL OF ONE TO
THREE INCHES. HIGH PRECIPITABLE WATER VALUES WILL REMAIN AND POOL
AROUND TWO INCHES AHEAD OF THE FRONTAL BOUNDARY ACROSS NORTHEAST AND
EAST CENTRAL KANSAS. GOOD FRONTOGENETICAL FORCING FROM SURFACE
THROUGH 700 MB IS NOTED TONIGHT ALONG WITH INCREASING LOW LEVEL JET
AND THETA CONVERGENCE/ISENTROPIC LIFT. DIFFLUENT FLOW ALOFT AND MID
LEVEL JET TONIGHT WILL ENHANCE VERTICAL MOTION. UPPER TROUGH WILL
MOVE ACROSS THE AREA OVERNIGHT AND EXIT TUESDAY MORNING. LOOKING
MORE LIKE AN MCS WILL FORM NORTH IN NEBRASKA AND PROPAGATE SOUTHEAST
ACROSS THE CWA. HAVE ISSUED A FLASH FLOOD WATCH FOR TONIGHT INTO
EARLY TUESDAY MORNING. BETTER CHANCE FOR SEVERE STORMS WILL RESIDE
ACROSS NORTH CENTRAL KANSAS THIS EVENING WHERE INSTABILITY AND SHEAR
ARE MORE FAVORABLE FOR HAIL AND WIND.

FOR TUESDAY THE FRONT WILL MOVE SOUTHEAST OUT OF THE AREA ALONG WITH
THE UPPER TROUGH. HAVE MAINTAINED POPS IN THE EAST IN THE MORNING
THEN WENT DRY IN THE AFTERNOON WITH SUBSIDENCE. COOLER TEMPERATURES
EXPECTED ON TUESDAY WITH CLOUDS AND SOME CAA BEHIND THE FRONT.
MAINLY WENT WITH HIGHS IN THE MID 70S TO NEAR 80.

53

DRIER AIR IN THE LLVLS WILL CONTINUE TO FILTER SOUTHWARD ACROSS
THE CWA TUESDAY NIGHT AND INTO EARLY WEDNESDAY. BY LATE IN THE DAY
WEDNESDAY...SOME WAA WILL BEGIN IN FAR NORTHCENTRAL KS...BUT THE
STRONGER ADVECTION AND BETTER LIFT WILL BE ON THE NOSE OF THE LLVL
JET ACROSS NEBRASKA WHICH VEERS TO THE WEST OVERNIGHT AND EARLY
THURSDAY. THIS MAY ALLOW FOR A LOW CHANCE FOR CONVECTION TO
DEVELOP/SPREAD EAST/SOUTHEASTWARD INTO THE NORTHERN 2/3 OF THE CWA
OVERNIGHT. WENT DRY FOR THURSDAY WITH THE JET/WAA WEAKENING. WITH
THE DECREASING CLOUDS TUESDAY NIGHT...IT WILL BE ANOTHER
UNSEASONABLY COOL NIGHT IN THE UPPER 50S TO LOW 60S...THEN WARM
TEMPS WEDNESDAY INTO THE MIDDLE 80S. THE WAA WILL CONTINUE INTO
THURSDAY WITH HIGHS WARMING INTO THE UPPER 80S TO LOW 90S.

MODELS CONTINUE TO BRING ANOTHER COLD FRONT INTO THE CWA ON FRIDAY
AND MOVE IT THROUGH INTO EARLY SATURDAY. THERE HAS BEEN A LOT
VARIABILITY WITH THE MODELS ON THE TIMING AND STRENGTH OF THE
FROPA. THEREFORE DECIDED TO KEEP LOW POPS GOING ACROSS THE
AREA FRIDAY INTO SATURDAY...ALTHOUGH AT SOME POINT...WHEN
CONFIDENCE/MODEL CONSISTENCY IS HIGHER...SHOULD BE ABLE TO NARROW
DOWN THE TIMEFRAME OF PRECIP POTENTIAL UNLESS THE FRONT SLOWS
SIGNIFICANTLY. KEPT HIGHS WARM ON FRIDAY GENERALLY IN THE LOW
90S...THEN THE MID 80S FOR SATURDAY. WITH NORTHWEST FLOW
PERSISTING THROUGH THE END OF THE WEEKEND INTO EARLY NEXT
WEEK...IT WILL REMAIN QUITE DIFFICULT TO FCST SMALL SCALE WAVES IN
THE FLOW AND ANY POSSIBLE MCSS THAT FAR OUT...BUT AT THIS POINT DO
NOT SEE ANYTHING SIGNIFICANT ENOUGH TO WARRANT ADDING LOW POPS TO
THE END OF THE EXTENDED FCST. THEREFORE WILL KEEP SUNDAY/MONDAY
DRY FOR NOW. 63

&&

.AVIATION...

SCATTERED THUNDERSTORMS WILL AFFECT THE TAF SITES THROUGH 00Z
TUESDAY AS AN MCV MOVES ACROSS THE AREA. MAIN UPPER
WAVE...ISENTROPIC LIFT AND MOISTURE ADVECTION WILL OCCUR TONIGHT
AHEAD OF AN APPROACHING SHORTWAVE TROUGH AND PRODUCE WIDESPREAD
SHOWERS AND THUNDERSTORMS. EXPECT VSBYS TO FALL INTO THE MVFR AND
IFR RANGE ALONG WITH CIGS MVFR AND BRIEFLY IFR. FRONTAL BOUNDARY
MOVES THROUGH BETWEEN 08Z AND 10Z TUESDAY SHIFTING WINDS TO THE
NORTHEAST THEN NORTH. SKIES MAINLY VFR OUTSIDE OF CONVECTION.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...FLASH FLOOD WATCH FROM 7 PM MONDAY
TO 7 AM TUESDAY FOR KSZ010-KSZ011-KSZ012-KSZ022-KSZ023-KSZ024-KSZ026-
KSZ036-KSZ038-KSZ039-KSZ040-KSZ055-KSZ056.

&&

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE TOPEKA KS
609 PM CDT MON JUL 20 2009

KSZ020-034-035-037-212315-
CLOUD-OTTAWA-DICKINSON-MORRIS-
609 PM CDT MON JUL 20 2009

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

.DAY ONE...THIS EVENING AND TONIGHT

PERIODS OF THUNDERSTORMS ARE EXPECTED ACROSS THE OUTLOOK AREA
TONIGHT. SOME OF THE STORMS MAY BE SEVERE WITH LARGE HAIL...DAMAGING
WINDS AND TORNADOES...MAINLY ACROSS CENTRAL KANSAS LATER THIS
EVENING. IN ADDITION...LOCALLY HEAVY RAINFALL IS EXPECTED ACROSS
MUCH OF NORTHEAST AND EAST CENTRAL KANSAS TONIGHT WHICH COULD LEAD
TO FLASH FLOODING. A FLASH FLOOD WATCH IS POSTED TONIGHT FOR MUCH
OF NORTHEAST AND EAST CENTRAL KANSAS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THUNDERSTORMS ARE POSSIBLE TUESDAY MORNING ACROSS PARTS OF
NORTHEAST AND EAST CENTRAL KANSAS.

THE CHANCE FOR THUNDERSTORMS RETURNS TO THE AREA FRIDAY INTO SATURDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS REQUESTED.

KSZ008>012-021>024-026-036-038>040-054>056-058-059-212315-
REPUBLIC-WASHINGTON-MARSHALL-NEMAHA-BROWN-CLAY-RILEY-POTTAWATOMIE-
JACKSON-JEFFERSON-GEARY-WABAUNSEE-SHAWNEE-DOUGLAS-LYON-OSAGE-
FRANKLIN-COFFEY-ANDERSON-
609 PM CDT MON JUL 20 2009

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

.DAY ONE...THIS EVENING AND TONIGHT

PERIODS OF THUNDERSTORMS ARE EXPECTED ACROSS THE OUTLOOK AREA
TONIGHT. SOME OF THE STORMS MAY BE SEVERE WITH LARGE HAIL AND
DAMAGING WINDS THE MAIN HAZARDS...MAINLY ACROSS NORTH CENTRAL
KANSAS LATER THIS EVENING. IN ADDITION...LOCALLY HEAVY RAINFALL IS
EXPECTED ACROSS MUCH OF NORTHEAST AND EAST CENTRAL KANSAS TONIGHT
WHICH COULD LEAD TO FLASH FLOODING. A FLASH FLOOD WATCH IS POSTED
TONIGHT FOR MUCH OF NORTHEAST AND EAST CENTRAL KANSAS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THUNDERSTORMS ARE POSSIBLE TUESDAY MORNING ACROSS PARTS OF
NORTHEAST AND EAST CENTRAL KANSAS.

THE CHANCE FOR THUNDERSTORMS RETURNS TO THE AREA FRIDAY INTO
SATURDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS MAY BE NEEDED THIS EVENING AND TONIGHT...MAINLY ACROSS
NORTH CENTRAL KANSAS.