Special Weather Statement, NWS Topeka, KS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
708 PM CDT FRI APR 8 2011

...MESOSCALE CONVECTIVE DISCUSSION...

.UPDATE...

STRONG TO SEVERE THUNDERSTORMS CONTINUE TO DEVELOP ACROSS NORTH
CENTRAL OKLAHOMA AND SOUTH CENTRAL KANSAS. CONVECTION IS
DEVELOPING NEAR THE TRIPLE POINT OF A WEAK SURFACE LOW...A
DRYLINE AND A WARM FRONT. PER BUNKERS...RIGHT SPLITTING STORMS
ARE ANTICIPATED TO PROPAGATE EAST NORTH EAST WITH LEFT SPLITTING
STORMS PROPAGATING NORTH NORTHEAST.

CIN REMAINS NEAR 50-100 J/KG ACROSS EAST CENTRAL KANSAS WITH MU
CAPE VALUES NEAR 2000-2500 J/KG. IF FORCING IS STRONG ENOUGH TO
OVERCOME THE CAPPING INVERSION...STRONG MID LEVEL LAPSE RATES
WILL SUPPORT LARGE HAIL. 0-6KM BULK SHEAR VALUES NEAR 50 KNOTS
WILL BE SUPPORTIVE OF STRONG WINDS. SURFACE WINDS ARE MORE BACKED
ACROSS EAST CENTRAL KANSAS WHERE 0-1KM HELICITY VALUES NEAR 150
M2/S2 RESIDE. IF STORMS ARE ABLE TO MAINTAIN THEIR INTENSITY
WHILE TRACKING NORTH INTO EAST CENTRAL KANSAS...THE ENVIRONMENTAL
WINDS WOULD BE FAVORABLE FOR THE POTENTIAL OF TORNADOES.

ANGLE

&&

.DISCUSSION...

STRATUS DECK AND FOG HAVE HELD IN ACROSS MUCH OF THE NORTHERN
PORTION OF THE CWA KEEPING TEMPERATURE DURING THE DAY MUCH COOLER
THAN INDICATED BY THE MODELS. WARM FRONTAL BOUNDARY IS SLOWLY
LIFTING NORTH ACROSS THE CWA WITH CLEARING TO THE SOUTH. EXPECT
FRONT TO CONTINUE TO MOVE SLOWLY TO THE NORTH. AS THE WARM FRONT
LIFTS NORTH A WEAK 500MB SHORTWAVE TROF WILL MOVE THROUGH THAT
COULD SET OFF A FEW ELEVATED THUNDERSTORMS THIS AFTERNOON INTO
THE OVERNIGHT. MODEL SOUNDINGS INDICATE DECENT MID LEVEL LAPSE
RATES WITH ELEVATED INSTABILITY. HOWEVER...MODEL SOUNDINGS ARE
RELATIVELY DRY ALOFT AND THUNDERSTORMS MAY HAVE SOME TROUBLE
DEVELOPING. HAVE INCLUDED A SLIGHT CHANCE OF POPS WITH THE WAVE
MOVING THROUGH AND THE ELEVATED INSTABILITY. HAVE INCLUDED HIGHER
POPS IN THE SOUTHEAST WITH CURRENT RADAR TRENDS INDICATE SOME
DEVELOPMENT OF SHOWERS MOVING IN FROM THE SOUTHWEST. OVERNIGHT
LOWS WILL BE ON THE WARM SIDE AS WARM AND MOIST AIR ADVECTS INTO
THE REGION BEHIND THE WARM FRONT. MODEL SOUNDINGS INDICATE A
STRONG INVERSION THAT WILL SET UP OVERNIGHT AND HAVE ADDED FOG TO
THE FORECAST WITH INCREASE MOISTURE ADVECTION.

STRONG SOUTHERLY WINDS WILL CONTINUE TO BRING IN WARM MOIST AIR
INTO THE REGION AT THE SURFACE AND AT 850MB ON SATURDAY. SURFACE
BASED INSTABILITY VALUES WILL INCREASE RAPIDLY DURING THE DAY.
HOWEVER...850MB TEMPERATURES WILL BE ABOVE 20 C AND SHOULD KEEP
MOST OF THE INSTABILITY CAPPED. HAVE INCLUDED A SLIGHT CHANCE FOR
THUNDERSTORMS ACROSS THE NORTHWEST PART OF THE CWA WHERE MODEL
INDICATE A WEAK CAP AND SOME WEAK CONVERGENCE DUE TO A DRYLINE.
THESE CONDITIONS WILL SET UP A WARM DAY WITH HIGH TEMPERATURES
NEAR 90 DEGREES ACROSS MUCH OF THE CWA.

AS THE MAIN UPPER TROUGH OVER THE ROCKIES BEGINS TO LIFT TO THE
EAST AND NORTHEAST INTO THE CENTRAL HIGH PLAINS SATURDAY
NIGHT...SOME SCATTERED/ISOLATED THUNDERSTORMS MAY LINGER/LIFT
NORTHEAST ALONG OR SLIGHTLY AHEAD OF THE DRY LINE IN THE NORTH
CENTRAL COUNTIES INTO THE EVENING WITH A STRONGLY SHEARED
ENVIRONMENT AND HIGHER CAPES (2000-2500 J/KG) IN THE 7-9 PM
TIMEFRAME BEFORE WEAKENING AS WEAKER CONVERGENCE IS OVERCOME BY
CAPPING INVERSION AND THE LOSS OF PEAK HEATING. HOWEVER...LOW
LEVEL JET WILL INCREASE AND SLOWLY VEER ACROSS MUCH OF THE CWA
THROUGH THE NIGHT WHICH COULD LEAD TO ADDITIONAL ELEVATED
CONVECTION SO WILL MAINTAIN CHANCE POPS NORTHWEST 1/2 OF THE CWA
WITH SLIGHT CHANCE POPS ELSEWHERE. WITH HIGHER DEWPOINTS AND
STRONG MIXING WILL KEEP LOWS IN THE 60S.

ON SUNDAY...MODELS ARE IN AGREEMENT ON BRINGING DRY PUNCH WEST TO
EAST ACROSS THE CWA THROUGH THE DAY. WILL GO DRY IN THE FAR NORTH
CENTRAL SUNDAY BEHIND THE LEADING EDGE OF DRY AIR...BUT INCREASE
EASTWARD TO CHANCE POPS MAINLY FOR THE EARLY TO MIDDAY HOURS
BEFORE THE DRIER AIR ARRIVES ALL AREAS BY MID TO LATE AFTERNOON.
THIS WOULD BE THE MOST LIKELY TIME FOR ANY STRONG TO SEVERE
THUNDERSTORMS IN THE CWA (ACROSS THE FAR EASTERN COUNTIES) UNLESS
THE TIMING SLOWS DOWN AND THE ARRIVAL OF THE DRIER AIR IS DELAYED
ALLOWING MORE CONVECTION TO DEVELOP DURING PEAK HEATING. THE NAM
IS STILL THE SLOWEST WITH THIS SCENARIO...BUT HAS BECOME MORE IN
LINE WITH THE FASTER GFS/EC MODELS. AS THE DRIER AIR OVERSPREADS
THE COUNTY WARNING AREA AND HIGHS REACH INTO THE 70S...SHOULD SEE
LOWEST RELATIVE HUMIDITY DROP INTO THE MIDDLE TO UPPER
20S...WHICH WOULD CREATE AN ELEVATED FIRE DANGER ACROSS MUCH OF
THE WESTERN CWA IN THE AFTERNOON. THIS WILL NEED TO BE MONITORED
FOR FIRE WEATHER CONCERNS OVER THE NEXT COUPLE OF DAYS.

ALTHOUGH A FEW SHOWERS ARE POSSIBLE SUNDAY NIGHT ACROSS THE
NORTHERN CWA...DRY AIR WILL REMAIN ENTRENCHED ACROSS THE AREA
INTO MONDAY AND TUESDAY IN THE WAKE OF THE DEPARTING UPPER TROUGH
WITH HIGHS IN THE 60S MONDAY...THEN GENERALLY THE LOWER 70S FOR
TUESDAY.

BY WEDNESDAY...MODELS STILL BRING ANOTHER SHORTWAVE TROUGH INTO
THE CENTRAL PLAINS AND AMPLIFY IT AS UPSTREAM RIDGING TAKES PLACE
ALONG THE WEST COAST. THE TROUGH WILL BECOME NEARLY CUTOFF SO
ONCE POPS BEGIN FOR CONVECTION ON WEDNESDAY...THEY CONTINUE WITH
SHOWER CHANCES INTO FRIDAY AS COLDER AIR WORKS INTO THE CWA.
AFTER HIGHS GENERALLY IN THE 60S WEDNESDAY AND THURSDAY...EXPECT
HIGHS IN THE 50S FOR FRIDAY.

&&

.AVIATION...

CEILINGS AND VISIBILITIES ARE EXPECTED TO GRADUALLY LOWER
OVERNIGHT. A WARM FRONT WILL REMAIN SOUTH OF THE TAF SITES
OVERNIGHT WITH MOISTURE POOLING ALONG THIS BOUNDARY AIDING IN
CEILINGS LOWERING TO IFR CATEGORY. REDUCED VISIBILITIES WILL ALSO
BE POSSIBLE WITH SURFACE WINDS WEAKENING NEAR 10-13Z. AFTER
15Z...THE WARM FRONT WILL LIFT NORTH AND SURFACE WINDS WILL SHIFT
TO THE SOUTH WITH WIND SPEEDS ABOVE 10 KNOTS AND GUSTS NEAR 20
KNOTS LIKELY. CEILINGS WILL IMPROVE TO VFR BY 18Z AS MIXING
INCREASES IN RESPONSE TO A TIGHTENING PRESSURE GRADIENT.

ANGLE

&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TOPEKA KS
552 PM CDT FRI APR 8 2011

KSZ008>012-020>024-026-034>040-054>056-058-059-092300-
REPUBLIC-WASHINGTON-MARSHALL-NEMAHA-BROWN-CLOUD-CLAY-RILEY-
POTTAWATOMIE-JACKSON-JEFFERSON-OTTAWA-DICKINSON-GEARY-MORRIS-
WABAUNSEE-SHAWNEE-DOUGLAS-LYON-OSAGE-FRANKLIN-COFFEY-ANDERSON-
552 PM CDT FRI APR 8 2011

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

.DAY ONE...TONIGHT.

SEVERE THUNDERSTORMS WILL BE POSSIBLE ACROSS PORTIONS OF EAST
CENTRAL KANSAS TONIGHT. THUNDERSTORMS DEVELOPING IN NORTHERN
OKLAHOMA ALONG WITH ADDITIONAL THUNDERSTORM DEVELOPMENT IN
SOUTHERN KANSAS COULD TRACK INTO EAST CENTRAL KANSAS THIS
EVENING. LARGE HAIL UP TO THE SIZE OF GOLFBALLS...DAMAGING WINDS
UP TO 70 MPH AND ISOLATED TORNADOES WILL BE POSSIBLE. A TORNADO
WATCH IS IN EFFECT UNTIL 1 AM CDT SATURDAY FOR PORTIONS OF EAST
CENTRAL KANSAS. FOR ADDITIONAL DETAILS...PLEASE SEE WCNTOP.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

THERE IS A CHANCE OF THUNDERSTORMS LATE SATURDAY AFTERNOON ACROSS
NORTH CENTRAL KANSAS. SOME OF THESE STORMS COULD BECOME SEVERE.

THE THREAT FOR STORMS CONTINUES ACROSS THE ENTIRE OUTLOOK AREA
THROUGH SATURDAY NIGHT AND INTO SUNDAY. SOME OF THESE STORMS MAY
ALSO BE SEVERE WITH THE POSSIBILITY OF LARGE HAIL AND STRONG
WINDS.

THERE WILL BE AN ELEVATED FIRE DANGER ACROSS NORTH CENTRAL KANSAS
SUNDAY AFTERNOON AS DRIER AIR OVERSPREADS THE AREA.

THUNDERSTORM CHANCES RETURN TO MOST OF THE AREA TUESDAY NIGHT
INTO THURSDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS EVENING IN PORTIONS OF EAST
CENTRAL KANSAS.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TOPEKA KS
840 PM CDT FRI APR 8 2011

KSZ054-090215-
LYON-
840 PM CDT FRI APR 8 2011

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN LYON COUNTY...

THROUGH 915 PM CDT...A STRONG THUNDERSTORM WILL MOVE NORTHEAST AT 40
MPH ACROSS PORTIONS OF SOUTHERN LYON COUNTY. NATIONAL WEATHER SERVICE
DOPPLER RADAR INDICATED THIS STORM IS CAPABLE OF PRODUCING PENNY SIZE
HAIL. SOME LOCATIONS THAT COULD BE AFFECTED INCLUDE OLPE...EMPORIA
AIRPORT...EMPORIA...NEOSHO RAPIDS...AMERICUS AND READING.

A TORNADO WATCH IS ALSO IN EFFECT.

&&

LAT...LON 3817 9636 3858 9625 3854 9595 3839 9594
      3816 9610 3816 9634
TIME...MOT...LOC 0140Z 206DEG 35KT 3821 9620

BLAIR