Special Weather Statement, NWS Kansas City, MO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
311 AM CDT FRI APR 22 2011

.DISCUSSION...

GEARING UP FOR THE NEXT ROUND OF WARM AIR ADVECTION GENERATED
ELEVATED CONVECTION AND POTENTIAL SEVERE FOR THIS MORNING...AND THEN
POTENTIAL FOR AFTERNOON SEVERE OVER THE EASTERN COUNTIES. HAVE BEEN
KEEPING AN EYE ON NORTHERN AND CENTRAL KS FOR NEW DEVELOPMENT AND
LATEST RADAR SHOWS NEW CONVECTION FORMING RIGHT ON SCHEDULE OVER
CENTRAL KS WITHIN THE LEFT EXIT REGION OF THE SWLY LOW LEVEL JET.
SPC MESO ANALYSIS PAGE SHOWS MODERATE TO STRONG SURFACE BASED MUCAPE
FROM 2000-3000 J/KG WITHIN THE WARM SECTOR OVER OK BEING TRANSPORTED
ON 60-70KT SWLY LOW LEVEL JET OVER THE STABLE BOUNDARY LAYER. MODELS
SHOW SIGNIFICANT 850-300MB MUCAPES OF 1500-2000J/KG AND 0-6KM SHEAR
IN THE 50-60KT RANGE...MORE THAN ENOUGH TO SUPPORT LARGE HAIL
PRODUCING STORMS WITH MID LEVEL ROTATION. ACTIVITY WILL LIKELY BE
FLYING SINCE THEY WILL BE ROOTED ABOVE 850MB WHERE WINDS WILL BE 50+
KTS. WHILE SOME TRAINING OF CELLS IS POSSIBLE NOT OVERLY CONCERNED
ON FLOODING POTENTIAL DUE TO SUCH FAST CELL MOTIONS.

NEGATIVELY TILTED SHORTWAVE COMING OUT OF THE CENTRAL HIGH PLAINS
WILL ENHANCE THIS MORNINGS CONVECTION AND GENERATE A SURFACE LOW
THAT WILL RIDE NORTHEAST ALONG A WARM FRONT FROM SOUTH CENTRAL KS
INTO THE CENTRAL PORTION OF THE CWA BY EARLY AFTERNOON. A COLD FRONT
WILL TRAIL FROM THIS LOW AND BECOME THE FOCUS FOR ANY THUNDERSTORM
REDEVELOPMENT. CURRENT THINKING IS STRONG/ISOLATED SEVERE
THUNDERSTORMS WILL FORM ALONG THIS COLD FRONT BY MID TO LATE
AFTERNOON...JUST AS THE FRONT IS EXITING THE EASTERN CWA. AREAS EAST
OF A KIRKSVILLE TO CLINTON LINE STAND A CHANCE OF SEEING A FEW
SEVERE THUNDERSTORMS. ALL FORMS OF SEVERE WEATHER INCLUDING LARGE
HAIL...DAMAGING WINDS...ISOLATED TORNADOES AND LOCALIZED FLOODING
WILL BE POSSIBLE FROM MID TO LATE AFTERNOON.

ONCE THE COLD FRONT PUSHES THROUGH DRY HIGH PRESSURE WILL BUILD INTO
THE REGION THIS EVENING AND BRING DRY AND SEASONABLY COOL WEATHER
THROUGH SATURDAY MORNING. HOWEVER...THE QUASI-ZONAL FLOW WE HAVE
BEEN UNDER FOR AROUND A WEEK WILL CONTINUE TO FACILITATE A BELT OF
STRONG WINDS WHICH WILL CARRY FAST MOVING IMPULSES BACK THROUGH THE
CENTRAL U.S. PLUS THE RAPID RETURN OF MID LEVEL WARM AIR ADVECTION
WILL SPELL INCREASING CLOUDS ACROSS THE REGION BY SATURDAY
AFTERNOON. ONE OF THESE WEAK IMPULSES MAY BE STRONG ENOUGH TO
GENERATE SOME AFTERNOON AND EVENING SPRINKLES/VERY LIGHT RAIN
SHOWERS ACROSS NORTHERN MO.

EASTER SUNDAY IS LOOKING LIKE PRETTY MUCH OF A WASHOUT AS INCREASING
WARM AIR ADVECTION ALOFT WILL TOP-DOWN SATURATE THE AIRMASS
NECESSITATING HIGH POPS FOR SUNDAY/SUNDAY NIGHT. WITH A FRONTAL
BOUNDARY HUNG UP JUST SOUTH OF THE CWA AND COPIOUS MOISTURE FROM THE
GULF OF MEXICO HEADING NORTH LATER FORECASTS WILL NEED TO BE
CONCERNED ABOUT HEAVY RAINFALL.

MJ

MEDIUM RANGE (MONDAY THROUGH FRIDAY)...

OPERATIONAL AND ENSEMBLE MEMBERS ARE IN GOOD GENERAL AGREEMENT THAT
THE PERSISTENT MOIST SWLY FLOW ALOFT AND BROAD TROUGHING OVER THE
CNTRL ROCKIES EARLY IN THE PERIOD WILL BE REPLACED BY MORE OF A NWLY
FLOW AND SUBSIDENCE REGIME WITH THE PASSAGE OF FULL LATITUDINAL
TROUGH INTO THE ERN CONUS BY WEDNESDAY. VERY GOOD SIGNAL FOR
EXPANSIVE THUNDERSTORMS ON MONDAY AFTERNOON/EVENING WITH STRONG
MOISTURE FLUX...DEEP MERIDIONAL FLOW...AND FAVORABLE DYNAMIC JET
SUPPORT. PASSAGE OF THIS INITIAL WAVE BY TUESDAY MORNING SHOULD
BRING DRIER AIR DOWNSLOPE INTO THE FORECAST AREA...WITH A SECONDARY
KICKER WAVE PULLING INTO THE TROUGH BASE BY WEDNESDAY MORNING. FEEL
PRIMARY DEEP MOISTURE AXIS WILL BE SHUNTED SOUTH BY THIS TIME...WITH
THE WAVE ACTING ON MORE ENHANCED BAROCLINICITY TOWARDS THE I-44/I-40
CORRIDOR...AND ONLY RESIDUAL SHRA FURTHER NORTH. A NICE PERIOD OF
DRY AND SEASONABLE WEATHER FOR THE END OF THE PERIOD...WITH THE
POSSIBILITY OF RENEWED STORMS BEYOND THIS BY NEXT WEEKEND. OVERALL
PATTERN WOULD SUGGEST TEMPERATURES NOT TERRIBLY FAR FROM
CLIMATOLOGY...WITH THE MORE LIKELY COOLER DAYS DURING PRECIPITATION
MONDAY AND POST-FRONTAL WEDNESDAY.

21

&&

.AVIATION...

WIDESPREAD IFR CONDITIONS PREVAIL ACROSS THE ENTIRE REGION FOR THE
BEGINNING OF THE 06Z TAF PACKAGE...AND WILL CONTINUE AS SUCH THROUGH
THE MORNING HOURS. RAPID CONVECTIVE DEVELOPMENT IS EXPECTED ACROSS
CNTRL KANSAS IN THE 08Z-10Z TIME FRAME...MOST LIKELY AFFECTING THE
TERMINAL CORRIDOR SOMETIME IN THE 10Z-13Z TIME FRAME. STEEP LAPSE
RATES ALOFT AND AMPLE ELEVATED INSTABILITY WOULD SUGGEST HAIL IN ANY
OF THESE STORMS...THOUGH RAPID FORWARD PROPAGATION OF 50+KT WOULD
KEEP RESIDENCE TIME OVER ANY SITE QUITE LIMITED.

RESIDUAL -SHRA MAY LINGER INTO THE MORNING HOURS...WITH CONTINUED
IFR/LOW MVFR CONDITIONS PREVALENT UNTIL BOUNDARY LAYER WINDS VEER
AND FRONTAL BOUNDARY APPROACHES INTO THE EARLY AFTERNOON. LOWER
CONFIDENCE AS TO HOW QUICKLY CIGS RISE AND BEGIN TO BREAK DURING THE
AFTERNOON...AS BUFR SOUNDINGS AND NUMERICAL GUIDANCE SUGGEST AT
LEAST MVFR CIGS UNTIL FROPA LATE IN THE AFTERNOON. ANY CONVECTIVE
REDEVELOPMENT IN THE AFTERNOON AND EVENING SHOULD REMAIN WELL TO THE
EAST OF TERMINALS...WITH VFR CONDITIONS FOR THE EVENING HOURS.

21

&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
505 AM CDT FRI APR 22 2011

KSZ025-057-060-102>105-MOZ001>008-011>017-020>025-028>033-037>040-
043>046-053-054-231015-
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-
505 AM CDT FRI APR 22 2011

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

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS CAN BE EXPECTED ACROSS THE REGION THIS
MORNING. A DEVELOPING COMPLEX OF STRONG THUNDERSTORMS WILL TRACK TO
THE EAST-NORTHEAST ACROSS AREAS GENERALLY NORTH OF I-70 THIS MORNING.
A FEW SEVERE THUNDERSTORMS PRODUCING VERY LARGE HAIL UP TO THE SIZE
OF GOLFBALLS WILL BE POSSIBLE. IN ADDITION...FREQUENT LIGHTNING AND
LOCALLY HEAVY RAINFALL WILL BE POSSIBLE WITH THIS GROWING AREA OF
THUNDERSTORMS.

LATER THIS AFTERNOON SCATTERED STRONG TO SEVERE THUNDERSTORMS ARE
EXPECTED TO REFORM ALONG AN EASTWARD MOVING COLD FRONT. AREAS EAST OF
A UNIONVILLE TO CLINTON LINE WILL HAVE THE BEST CHANCE FOR SEVERE
WEATHER DURING THE MID TO LATE AFTERNOON HOURS. LARGE HAIL...DAMAGING
WINDS AND AN ISOLATED TORNADO WILL BE POSSIBLE WITH ANY OF THESE
STORMS. THE THREAT OF SEVERE WEATHER WILL END WITH THE PASSAGE OF THE
COLD FRONT.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

SEVERAL MORE UPPER LEVEL WEATHER SYSTEMS WILL TRACK THROUGH THE
CENTRAL PLAINS SUNDAY THROUGH MONDAY AND BRING PERIODIC THUNDERSTORMS
TO THE REGION. SEVERE THUNDERSTORMS WILL BE POSSIBLE DURING THIS
TIME. IN ADDITION...A WARM FRONT OVER SOUTHERN MISSOURI WILL LIFT
SLOWLY NORTHWARD AND ANCHOR REPEATED BANDS OF THUNDERSTORMS WHICH
COULD RESULT IN HEAVY RAINFALL. THIS COMBINED WITH RAINFALL FROM
THURSDAY NIGHT AND FRIDAY COULD RESULT IN WIDESPREAD FLOODING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS MORNING OVER MOST OF THE REGION...AND
AGAIN FRIDAY AFTERNOON FOR AREAS EAST OF A UNIONVILLE TO CLINTON LINE.

MJ

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