Special Weather Statement, NWS Kansas City, MO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1140 AM CDT SUN MAY 22 2011

...UPDATED MESOSCALE DISCUSSION...

.DISCUSSION...

...MESOSCALE DISCUSSION...

SLIGHTLY MORE UNCERTAINTY REGARDING CONVECTIVE INITIATION...
PLACEMENT...AND TIMING AS OPPOSED TO YESTERDAY...WITH VARIOUS
OPERATIONAL AND HIGH RESOLUTION DIRECT CONVECTIVE MODELS NOT
DEPICTING A PARTICULARLY CONSISTENT PICTURE. IN GENERAL...FAVOR SOME
BLEND OF RECENT 3KM HRRR RUNS ALONG WITH 00Z 4 KM NSSL
WRF-ARW...AWAITING OUTPUT FROM THE 12Z 4 KM WRF-NMM. IN THE LOW
LEVELS...SEVERAL BOUNDARIES ARE DISCERNIBLE ON VISIBLE SATELLITE
IMAGERY 1) A SHALLOW GRAVITY WAVE MOVING SOUTHEAST PAST A
MOBERLY-CHANUTE LINE AND 2) A PACIFIC FRONT/PSEUDO DRYLINE
ASSOCIATED WITH A DEEPER SFC-H8 BOUNDARY AND VEERED WIND PROFILE
FROM NEAR LAMONI-TOPEKA. BETTER DEEP CU DEVELOPMENT HAS BEEN NOTED
RECENTLY ALONG THE LATTER BOUNDARY DUE TO NOTABLE MOISTURE
CONVERGENCE AND WEAKER ELEVATED INHIBITION.

UNLIKE YESTERDAY...IT IS VERY DIFFICULT TO IDENTIFY ANY DEFINED
SHORTWAVE IN SATELLITE IMAGERY WHICH WOULD HELP FOCUS CONVECTIVE
DEVELOPMENT...AND UPSTREAM MIDLEVEL TEMPERATURES IN THE H5 LAYER ARE
ACTUALLY WARMER (ALTHOUGH WEAK CAA CAN BE NOTED IN THE CAPPING H8-H7
LAYER). HOWEVER...GIVEN THE IMPRESSIVE CLASSIC PLAINS SEVERE WEATHER
12Z KTOP SOUNDING...ALONG WITH BOUNDARY LAYER MOISTURE CONVERGENCE
STRONGER...AND THE WARM SECTOR CHARACTERIZED BY MLCAPES AOA 3000
J/KG ALREADY AT 16Z IN A WEAKLY CAPPED ENVIRONMENT...FEEL DEEPER
(AND POSSIBLY EXPLOSIVE) CONVECTIVE DEVELOPMENT WILL BREACH THE
INHIBITION EARLY THIS AFTERNOON ALONG THE SFC-H8 BOUNDARY (MOST
LIKELY IN THE VICINITY OF A KMKC-KCDJ-KOTM LINE). BULK 0-6KM SHEAR
VALUES IN EXCESS OF 40KT WILL SUPPORT SUPERCELL TYPE
STRUCTURES...WITH IMPRESSIVE 0-1KM SHEAR NEAR 30 KT SUPPORTING
STRONG INFLOW AND LOW LEVEL MESOCYCLOGENESIS (0-1KM AND 0-3KM SRH
BOTH APPROACHING 300 M2/S2 IN FAR NERN MISSOURI). GIVEN VEERED
BOUNDARY LAYER WIND PROFILES AND ALIGNMENT OF EXPECTED CONVECTIVE
CELLS...SOME DESTRUCTIVE INTERFERENCE CAN BE EXPECTED...AS WELL AS
DCAPE VALUES WELL IN EXCESS OF 1000 J/KG PROMOTING MORE DOWNDRAFT
PRODUCTION. NEVERTHELESS...THERE APPEARS TO BE A SMALL WINDOW FOR
ISOLATED TORNADOES UPON INITIAL CONVECTIVE MATURITY TOWARDS THE ERN
REACHES OF THE FORECAST AREA.

ALL TOLD...GREATEST THREAT STILL APPEARS TO BE THE POTENTIAL FOR
GIANT HAIL PRODUCTION WITH ANY STORM THAT FORMS TODAY. MIDLEVEL
H7-H5 LAPSE RATES PER 12Z SOUNDINGS AND OBJECTIVE ANALYSIS REMAIN
VERY IMPRESSIVE (AOA 8 C/KM)...AND ALTHOUGH THIS MEASURE MAY
DECREASE SLIGHTLY TODAY (COMBINATION OF SLIGHT COOLING AT H7 AND
WARMING AT H5)...TREMENDOUS AMOUNTS OF CAPE IN THE -10C TO -30C HAIL
GROWTH REGION ARE ALREADY EVIDENT (AT LEAST 700 J/KG AT 16Z). SHEAR
PARAMETERS WITHIN STORMS WILL PROMOTE ROTATING UPDRAFTS WITH
AVAILABLE ENERGY LIKELY EXCEEDING 3500-4000 J/KG BY PEAK
HEATING...SUPPORTING HAIL AT LEAST THE SIZE OF GOLF BALLS (IF NOT
MUCH BIGGER). EVENTUALLY...STORMS MAY CONGEAL INTO MINI-BOWS AND
BROKEN LINES...PUSHING INTO ERN/SRN MISSOURI THIS EVENING.

21

&&

.PREVIOUS DISCUSSION...
/442 AM CDT SUN MAY 22 2011/
THE WET AND ACTIVE WEATHER PATTERN EXPERIENCED OVER THE PAST COUPLE
OF DAYS WILL CONTINUE TODAY AND INTO THE MIDDLE OF NEXT WEEK. THE
UPPER LEVEL LOW SITUATED OVER THE NORTHERN PLAINS WILL SLOWLY TRACK
EASTWARD...APPROACHING THE GREAT LAKES REGION BY MONDAY. IN ADDITION
TO THIS UPPER LEVEL LOW...A SECONDARY TROUGH WILL BEGIN TO MOVE INTO
THE PACIFIC NORTHWEST TODAY AND DIG SOUTHWARD ACROSS THE WESTERN
CONUS BY THE BEGINNING OF THE WEEK. WITH THIS PATTERN IN PLACE...A
SOUTHERLY/SOUTHWESTERLY FLOW WILL PERSIST OVER THE SOUTHERN AND
CENTRAL PLAINS THROUGH THE BEGINNING OF THE WEEK.

FOR TODAY...MAIN FOCUS IS ON THE SURFACE LOW SITUATED OVER CENTRAL
SOUTH DAKOTA AT 09Z THAT WILL PROGRESS EASTWARD THROUGH THE DAY. THE
ASSOCIATED COLD FRONT EXTENDED TO THE SOUTH INTO THE CENTRAL PLAINS
WILL MOVE EASTWARD ACROSS THE FORECAST AREA THIS AFTERNOON AND THIS
EVENING...WITH PRECIPITATION FORMING ALONG AND AHEAD OF THIS
BOUNDARY. THE BOUNDARY WILL BE SITUATED ACROSS EAST CENTRAL KANSAS
THIS MORNING...TRACKING INTO EXTREME EASTERN KANSAS AND WESTERN
MISSOURI BY EARLY THIS AFTERNOON. BEFORE THE FRONT MOVES INTO THE
AREA...COULD SEE SOME BREAKS IN THE CLOUD COVER THAT WILL HELP WITH
THE DIURNAL HEATING. AS THE FRONT MOVES INTO THE AREA...COULD SEE
SHOWERS AND THUNDERSTORMS INITIATING BETWEEN 17Z-20Z ALONG A LINE
STRETCHING FROM BETHANY TO KANSAS CITY TO PAOLA KS. THIS LINE OF
THUNDERSTORMS ALONG AND AHEAD OF THE FRONT WILL MOVE EASTWARD ACROSS
THE FORECAST AREA THROUGH THE AFTERNOON HOURS...EXITING THE REGION
LATE THIS EVENING. MODELS SHOWING PLENTY OF MUCAPE OVER THE AREA
THIS AFTERNOON BUT 0-6KM SHEAR LOOKS TO BE FAIRLY LOW...GENERALLY
LESS THAN 40KTS...AND LAPSE RATES ARE NOT AS STEEP AS THEY APPROACH
THE -10C TO -30C HAIL GROWTH ZONE. WITH THESE CONDITIONS...SOME
STORMS COULD BE CAPABLE OF BECOMING SEVERE...WITH LARGE HAIL AND
STRONG WINDS BEING THE PRIMARY THREATS.

ONCE THIS SYSTEM MOVES EAST OF THE AREA...WILL SEE A BRIEF DRY
PERIOD OVERNIGHT EARLY MONDAY MORNING. HOWEVER OUR FOCUS QUICKLY
WILL BE SHIFTED TO A SURFACE LOW OVER THE TEXAS/OKLAHOMA PANHANDLES.
AN ASSOCIATED WARM FRONT WILL STRETCH EASTWARD INTO SOUTHEAST KANSAS
AND SOUTHWEST MISSOURI ON MONDAY...WITH SHOWERS AND THUNDERSTORMS
DEVELOPING ALONG AND SOUTH OF THIS BOUNDARY. STILL SOME
DISCREPANCIES IN THE MODELS WITH THE POSITIONING OF THIS WARM
FRONT...WHICH WILL ULTIMATELY AFFECT WHERE THE GREATEST
PRECIPITATION CHANCES WILL BE DURING THE DAY ON MONDAY. MODELS SHOW
THE FRONT LIFTING NORTHWARD INTO CENTRAL MISSOURI MONDAY
AFTERNOON...WHICH WILL SPREAD THE SHOWERS AND THUNDERSTORMS
NORTHWARD INTO THE REGION AND IMPACTING MUCH OF THE AREA BY TUESDAY
MORNING. THIS PRECIPITATION WILL LINGER OVER THE REGION INTO
WEDNESDAY AS THE SURFACE LOW STARTS TO TRACK EASTWARD...WITH THE LOW
EAST OF THE AREA BY THURSDAY. A WEAK RIDGE WILL MOVE INTO THE
CENTRAL PLAINS BEHIND THIS SYSTEM...BRINGING DRY CONDITIONS FOR
THURSDAY. HOWEVER...COULD SEE AN UPPER LEVEL SYSTEM SWEEP OVER THE
REGION FRIDAY/FRIDAY NIGHT BEFORE A LARGER RIDGE STARTS BUILDINGS
ACROSS THE ROCKY MOUNTAINS ON SATURDAY.

WITH SEVERAL ROUNDS OF PRECIPITATION WITH EMBEDDED CONVECTION
EXPECTED TO CONTINUE INTO THE MIDDLE OF THE WEEK...WILL CONTINUE TO
MONITOR THE THREAT FOR HEAVY RAINFALL...LOCALIZED FLASH FLOODING AND
RIVER FLOODING AS SEVERAL INCHES OF RAIN IS POSSIBLE ACROSS THE
FORECAST AREA.

ACH

&&

.AVIATION...

FOR THE 12Z TAFS...THE LOWER LEVELS OF THE ATMOSPHERE REMAIN QUITE
MOIST WITH MVFR CONDITIONS ACROSS THE TERMINALS. CEILINGS WILL ONCE
AGAIN RISE TO VFR THIS MORNING DUE TO SOLAR INSOLATION.
OTHERWISE...LOW LEVEL DRYING WILL SLOWLY WORK EAST INTO THE
TERMINALS LATE THIS AFTERNOON AND THIS EVENING. A FEW THUNDERSTORMS
MAY ACCOMPANY THE WEAK DRY LINE LATE THIS AFTERNOON BUT THE CHANCES
ARE LOW. OTHERWISE...VFR CONDITIONS ARE EXPECTED TONIGHT.

DB

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
106 PM CDT SUN MAY 22 2011

KSZ025-057-060-102>105-MOZ001>008-011>017-020>025-028>033-037>040-
043>046-053-054-231130-
ATCHISON KS-MIAMI-LINN KS-DONIPHAN-LEAVENWORTH-WYANDOTTE-JOHNSON KS-
ATCHISON MO-NODAWAY-WORTH-GENTRY-HARRISON-MERCER-PUTNAM-SCHUYLER-
HOLT-ANDREW-DE KALB-DAVIESS-GRUNDY-SULLIVAN-ADAIR-BUCHANAN-CLINTON-
CALDWELL-LIVINGSTON-LINN MO-MACON-PLATTE-CLAY-RAY-CARROLL-CHARITON-
RANDOLPH-JACKSON-LAFAYETTE-SALINE-HOWARD-CASS-JOHNSON MO-PETTIS-
COOPER-BATES-HENRY-
106 PM CDT SUN MAY 22 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHWEST...NORTH CENTRAL AND
WEST CENTRAL MISSOURI...AS WELL AS EXTREME EASTERN KANSAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT

SCATTERED SEVERE THUNDERSTORMS WILL DEVELOP EARLY THIS AFTERNOON
FROM EAST CENTRAL KANSAS THROUGH NORTHEAST MISSOURI...WITH STORMS
MOVING EAST AND SOUTH ACROSS THE OUTLOOK AREA THROUGH EARLY THIS
EVENING. LOCATIONS EAST OF THE INTERSTATE 35 CORRIDOR WILL BE MOST
SUSCEPTIBLE TO EXPERIENCE SEVERE WEATHER...WITH ISOLATED
TORNADOES...DAMAGING WIND GUSTS...AND ESPECIALLY VERY LARGE HAIL
LIKELY.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

THUNDERSTORMS WILL BE POSSIBLE MONDAY AND MONDAY NIGHT...MAINLY FOR
LOCATIONS ALONG AND SOUTH OF THE MISSOURI RIVER. THERE WILL BE A
SLIGHT THREAT FOR SEVERE WEATHER DURING THE LATE AFTERNOON AND
EVENING HOURS...WITH LARGE HAIL THE PRIMARY THREAT.

ANOTHER WEATHER SYSTEM WILL MOVE ACROSS THE CENTRAL ROCKIES AND INTO
THE PLAINS ON TUESDAY AND WEDNESDAY...BRINGING ADDITIONAL ROUNDS OF
THUNDERSTORMS TO THE REGION. THERE IS A THREAT FOR SEVERE WEATHER
LATE TUESDAY AFTERNOON AND EVENING...ESPECIALLY ACROSS THE WESTERN
PARTS OF THE OUTLOOK AREA. WHILE LARGE HAIL AND DAMAGING WINDS WILL
BE THE PRIMARY THREATS...AN ISOLATED TORNADO MAY ALSO BE POSSIBLE. ON
WEDNESDAY...THE THREAT FOR SEVERE WILL BE MUSH LOWER.

ALTHOUGH PRECIPITATION EVENTS WILL BE SCATTERED AND NOT CONTINUOUS
FOR THE NEXT SEVERAL DAYS...LOCALLY HEAVY RAINFALL...ESPECIALLY IN
THUNDERSTORMS...WILL LIKELY DEVELOP. TOTAL RAINFALL ACCUMULATIONS
THROUGH THE MIDDLE OF NEXT WEEK MAY EXCEED SEVERAL INCHES IN SOME
LOCATIONS ACROSS THE OUTLOOK AREA. THIS WILL INCREASE THE THREAT FOR
LOCALIZED FLASH FLOODING...AND WILL LIKELY PUSH SOME STREAMS AND
RIVERS INTO FLOOD THROUGH THIS WEEKEND AND INTO THE MIDDLE OF NEXT
WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE NEEDED THIS AFTERNOON EAST OF THE
INTERSTATE 35 CORRIDOR. SPOTTER ACTIVATION MAY ALSO BE NEEDED MONDAY
AFTERNOON AND EVENING...AS WELL AS LATE TUESDAY AFTERNOON AND EVENING.

21

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
130 PM CDT SUN MAY 22 2011

MOZ022-023-030-031-221915-
CALDWELL MO-CARROLL MO-LIVINGSTON MO-RAY MO-
130 PM CDT SUN MAY 22 2011

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN RAY...SOUTHWESTERN
LIVINGSTON...NORTHWESTERN CARROLL AND SOUTHEASTERN CALDWELL COUNTIES
UNTIL 215 PM CDT...

AT 129 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM NEAR COWGILL...OR 17 MILES SOUTHEAST OF
HAMILTON...MOVING NORTHEAST AT 25 MPH.

HAIL UP TO THE SIZE OF NICKELS IS EXPECTED WITH THIS STORM.

LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...
  BRAYMER...STET AND LUDLOW.

THIS STORM MAY INTENSIFY....AND A TORNADO WATCH IS IN EFFECT FOR THIS
AREA. BE CERTAIN TO MONITOR LOCAL RADIO AND TV STATIONS...AS WELL AS
LOCAL CABLE TV OUTLETS....FOR ADDITIONAL INFORMATION AND POSSIBLE
WARNINGS FROM THE NATIONAL WEATHER SERVICE.

LAT...LON 3975 9381 3963 9359 3946 9354 3935 9393
      3949 9409
TIME...MOT...LOC 1830Z 242DEG 21KT 3953 9386

SF