Severe Thunderstorm Warning 75, NWS Kansas City, MO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1245 AM CDT FRI MAY 7 2010

...UPDATED AVIATION DISCUSSION...

.UPDATE...
/1059 PM CDT THU MAY 6 2010/
STOUT SHORT WAVE TROUGH CENTERED ACROSS WESTERN SOUTH DAKOTA HAS
RESULTED IN HEIGHT FALLS AND SUBSEQUENT LARGE SCALE ASCENT ACROSS THE
CENTRAL PLAINS. ASSOCIATED SFC LOW HAS BECOME WELL-DEFINED ACROSS
SOUTHWESTERN KS/NORTHWESTERN OK WITH ATTENDANT WARM FRONT SHARPENING
FROM NEAR ST JOHN KANSAS EASTWARD TO NEAR CLINTON MISSOURI. ELEVATED
CONVECTION HAS DEVELOPED WITHIN WARM AIR ADVECTION REGIME ACROSS
NORTHERN MISSOURI AS LLJ HAS INCREASED TO 50-55KTS VIA AREA
PROFILERS. THIS HAS TRANSPORTED INCREASINGLY UNSTABLE AIR MASS
NORTHWARD CHARACTERIZED BY MUCAPE VALUES OF 500-1000 J/KG. CONVECTION
HAS BECOME STRONG TO SEVERE IN THE PAST COUPLE OF HOURS BOTH WITHIN
WAA ACTIVITY AS WELL AS WITH ISOLATED SUPERCELL CLOSER TO THE SFC
WARM FRONT ACROSS EAST-CENTRAL KS. CONVECTION SHOULD CONTINUE TO MOVE
EASTWARD WITH TIME WITH SEVERE THREAT PERSISTING INTO THE OVERNIGHT
HOURS. LATEST RADAR DEPICTIONS INDICATE 50 DBZ CORES NEEDED FOR
SEVERE HAIL AOA 35KFT WITH 60 DBZ CORES NEAR 25KFT. LARGE HAIL WILL
CONTINUE TO BE THE MAIN THREAT WITH CONVECTION ACROSS NORTHERN
MISSOURI WITH ISOLATED STRONG WIND GUSTS POSSIBLE AS WELL. AS
PERSISTENT SUPERCELL ACROSS EAST-CENTRAL KANSAS PROPAGATES
EAST...VERY LARGE HAIL UP TO BASEBALLS WILL BE POSSIBLE ALONG WITH 70
MPH STRAIGHT LINE WINDS.

DEROCHE

&&

.DISCUSSION...
/350 PM CDT THU MAY 6 2010/
SHORT TERM (TONIGHT-SATURDAY)...

SHORT TERM CONCERNS CENTER AROUND SEVERE THUNDERSTORM POTENTIAL
THIS EVENING. DESPITE A TOP-TEN DAY AROUND THE AREA WITH MILD
TEMPERATURES AND DRY EASTERLY FLOW...SIGNIFICANT CHANGES ARE
EXPECTED IN THE NEXT 3 TO 6 HOURS.

AT 20Z...SURFACE ANALYSIS DEPICTED A VERY SHARP WARM FRONT
STRETCHING FROM WRN KS TO NEAR EMPORIA THEN ARCING SEWD TOWARD
NEVADA MISSOURI. SOUTH OF THIS BOUNDARY...TEMPERATURES HAVE WARMED
INTO THE MID-UPPER 80S AND GULF MOISTURE RETURN HAS BEEN FAR MORE
ROBUST THAN PREVIOUSLY ANTICIPATED WITH LOW 60F DEWPOINTS ALREADY
PRESENT ACROSS SE KS/SW MO.

LACK OF CLOUD COVER ACROSS THE WARM SECTOR...AND STABILIZED CLOUD
STREETS ACROSS CENTRAL KS INTO NRN MO PER VISIBLE IMAGERY SUGGEST
THE PRESENCE OF A STRONG CAP ACROSS THE AREA. THIS CAP SHOULD
EFFECTIVELY HOLD UNTIL EARLY EVENING...AT WHICH POINT A GRADUALLY
MOISTENING ELEVATED MIXED LATER WILL BE TRIGGERED BY A DEVELOPING
NOCTURNAL JET. FINER RESOLUTION MODELS AND THE HIGH-RESOLUTION RAPID
REFRESH MODEL SUGGEST THUNDERSTORM INITIATION BETWEEN EMPORIA AND
KANSAS CITY SHORTLY AFTER 00Z...WHICH LOOKS REASONABLY GIVEN CURRENT
CONDITIONS...ALTHOUGH IT MUST BE NOTED THAT IN THE ABSENCE OF RECENT
UPPER AIR DATA...THE STRENGTH OF THE CAP AND FORCING TO OVERCOME IT
IS STILL UNKNOWN. ASSUMING THIS CAP WILL BE REMOVED AT SOME POINT
EARLY THIS EVENING...MODERATE ELEVATED INSTABILITY ON THE ORDER OF
1500 J/KG...COUPLED WITH STRONG DEEP LAYER SHEAR WOULD PROMOTE A
THREAT OF LARGE HAIL AND DAMAGING WINDS WITH SCATTERED SUPERCELLS
BEING THE PRIMARY STORM MODE. A WIND THREAT COULD BE ACCENTUATED
NORTH THE WARM FRONT WHERE CONTINENTAL DRY LOW LEVEL AIR COULD
ACCENTUATE THE DOWNDRAFTS. THE TORNADO CONCERN IS CERTAINLY HIGHER
THAN I WOULD HAVE PREVIOUSLY ANTICIPATED GIVEN THE CLOSER PROXIMITY
OF THE WARM FRONT TO THE EXPECTED INITIATION AREA...COUPLED WITH
MUCH IMPROVED MOISTURE QUALITY TO THE SOUTH. KINEMATIC PROFILES ARE
MORE THAN SUPPORTIVE OF STRONG LOW LEVEL ROTATION GIVEN ERLY SFC
WINDS OF 15-20 KNOTS AND 35-40 KNOTS OF SWRLY FLOW AT 850MB. THIS
WOULD FAVOR A LOCALLY ENHANCED SEVERE THREAT FOR STORMS RIDING
EASTWARD ALONG THE RETREATING WARM FRONT WHERE A NARROW W-E CORRIDOR
OF COOLER TEMPS/HIGHER MOISTURE COULD LEAD TO MORE FAVORABLE LCL/LFC
HEIGHTS.

THIS ACTIVITY SHOULD SLOWLY SPREAD EAST/NORTH THIS EVENING...
CONTINUING THE SEVERE THREAT INTO THE NORTH CENTRAL MISSOURI. THE
FOCUS WILL THEN SHIFT BACK TOWARD THE WEST FOR A POTENTIAL SECOND
EVENT IMPACTING NE KS/NW MO AROUND AND AFTER MIDNIGHT. ASSUMING A
SECOND AREA OF THUNDERSTORMS DEVELOP OVER N CENTRAL KS CLOSER TO THE
WARM FRONT/SFC LOW JUNCTION...THIS ACTIVITY WILL PROPAGATE EASTWARD
OVERNIGHT...POSSIBLY GROWING UPSCALE INTO A SLIGHTLY ELEVATED MCS.
SOME POTENTIAL FOR MIXED-MODES INCLUDING SUPERCELLS WILL EXIST OVER
THE NW CWA LATER TONIGHT WITH SOME POTENTIAL FOR TRAINING STORMS.

ALL OF THIS ACTIVITY SHOULD EXIT THE NRN CWA TOMORROW MORNING...WITH
STRONG NW WINDS USHERING IN MUCH COOLER/DRIER ARE INTO THE REGION
FOR THE WEEKEND. LOW TEMPERATURES SHOULD REMAIN ABOVE CRITICAL
LEVELS...BUT WITH PROJECTED MINIMUMS IN THE UPPER 30S FOR SATURDAY
AND SUNDAY MORNINGS...TROPICAL VEGETATION SHOULD BE BROUGHT INDOORS
TO PREVENT DAMAGE.

BOOKBINDER

MEDIUM RANGE (SUNDAY THROUGH THURSDAY NIGHT)...

NEXT WEEK LOOKS TO BRING ACTIVE WEATHER TO THE CENTRAL PORTION OF
THE U.S.  THE 00Z ECMWF AND 12Z GFS HAVE SOME MINOR DIFFERENCES BUT
BOTH SHOW THE SAME GENERAL UPPER PATTERN.  UPPER RIDGING INCREASES
OVER THE AREA BY SUNDAY EVENING IN RESPONSE TO A SHORTWAVE PUSHING
INTO THE GREAT BASIN REGION. LOOKING FURTHER UPSTREAM...A SECOND
SYSTEM IS PROGGED TO BE CENTERED OFF THE COAST OF BRITISH COLUMBIA.
THE LEAD PIECE OF ENERGY WILL MAKE ITS WAY INTO THE PLAINS BY MONDAY
EVENING WITH THE SECOND SYSTEM CARVING OUT A SPOT ACROSS THE DESERT
SOUTHWEST. BY LATE IN THE FORECAST PERIOD...THE MODELS DO SHOW MORE
VARIABILITY AS THE GFS IS STRONGER AND A BIT FASTER WITH THE SECOND
SYSTEM...BRINGING IT INTO THE PLAINS BY FRIDAY.

AT THE SURFACE...TRANQUIL HIGH PRESSURE WILL BEGIN TO SHIFT EASTWARD
ON SUNDAY.  HELD ONTO SOME SLIGHT TO CHANCE POPS AS WAA/ISENTROPIC
LIFT COMMENCES ON THE BACKSIDE OF THE DEPARTING HIGH.  MORE
WIDESPREAD THUNDERSTORMS ARE EXPECTED MONDAY THROUGH EARLY TUESDAY
AS MOISTURE DEEPENS AND THE UPPER ENERGY REACHES THE PLAINS.  IF THE
GUIDANCE IS CORRECT...TUESDAY NIGHT LOOKS TO BE THE BEST CHANCE OF
DRY WEATHER NEXT WEEK...AS THE MAIN SURFACE STORM AND COLD FRONT
PUSH EAST OF THE FORECAST AREA.  THE REMAINDER OF THE FORECAST HAS
SLIGHT TO LOW CHANCE POPS FOR NOW...THE COLD FRONT WILL LIKELY STALL
SOMEWHERE NEAR THE AREA.  THERE IS QUITE A BIT OF UNCERTAINTY HOW
FAR SOUTH IT STALLS...AND IF ADDITIONAL CONVECTION ALONG THE
BOUNDARY COULD PUSH IT FURTHER SOUTH. AS FOR TEMPERATURES...THE
MEDIUM RANGE FORECAST PERIOD WILL START OUT COOL ON SUNDAY...LOW TO
MID 60S...THEN DECENT WARMING WILL COMMENCE AHEAD OF THE APPROACHING
SYSTEM.  BEFORE THE SURFACE FRONT PUSHES THROUGH ON
TUESDAY...SOUTHERN PORTIONS MAY APPROACH 80 DEGREES WITH THE
REMAINDER OF THE AREA IN THE 70S.

SAW

&&

.AVIATION...
FOR THE 06Z TAFS...BIGGEST CONCERN IS WITH THE STRONG STORM IN
NORTHEAST KANSAS THAT WILL BE MOVING THROUGH THE KSTJ TERMINAL
TOWARD 07Z...WITH THE POTENTIAL OF STRONG WINDS AND LARGER HAIL. A
SECONDARY STORM MAY FOLLOW IN BEHIND WITH WINDS AND HAIL AS
WELL...SO WILL KEEP A MENTION OF HAIL IN THROUGH 08Z. MORE STORMS
EVEN FURTHER WEST ARE ALSO CAUSING WIND GUSTS...SO WILL KEEP A
MENTION OF GUSTY WINDS AND STORMS IN AT KSTJ THROUGH 11Z. FOR THE
KANSAS CITY TERMINALS STORMS THAT HAVE BEEN WEAKENING WILL BE MOVING
THROUGH AROUND 06Z...THEN THE KANSAS STORMS APPEAR TO BE TRACKING
FAR ENOUGH NORTH TO MISS KMCI. HOWEVER...MAY BE CLOSE...SO FOR NOW
WILL ONLY HAVE THUNDER MENTIONED FOR THE FIRST HOUR AND KEEP AN EYE
ON THE PROGRESS OF THE STORMS IN NORTH CENTRAL KANSAS. WILL
INTRODUCE LLWS TO THE KANSAS CITY TERMINALS AS 2K FOOT WINDS ARE
EXPECTED TO BE AROUND 40 KTS UNTIL 925 MB LOW MOVES CLOSER LATE
TONIGHT. STORMS SHOULD BE EXITING THE AREA BY DAYBREAK WITH GUSTY
NORTHWEST WINDS TAKING OVER BEHIND THE FRONT. SOME MVFR CIGS ARE
EXPECTED TO FOLLOW IN BEHIND THIS FRONT...BUT IMPROVE BY MIDDAY.

PC

&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
703 PM CDT THU MAY 6 2010

KSZ025-057-060-102>105-MOZ001>008-011>017-020>025-028>033-037>040-
043>046-053-054-080015-
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-
703 PM CDT THU MAY 6 2010

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

.DAY ONE...TONIGHT

 A WARM FRONT HAS SHARPENED FROM CENTRAL KANSAS EASTWARD INTO
 SOUTHWESTERN MISSOURI...CURRENTLY ALONG A HAYS KANSAS TO EMPORIA
 KANSAS TO CLINTON MISSOURI LINE. THIS FRONT WILL SERVE AS A FOCUS
 FOR STRONG TO SEVERE THUNDERSTORM DEVELOPMENT ALONG AND NORTH OF THE BOUNDARY
 THIS EVENING AND TONIGHT...WITH INITIATION POSSIBLE ACROSS EAST-
 CENTRAL KANSAS BY 9 PM. THESE STORMS WILL BE CAPABLE OF PRODUCING
 LARGE HAIL...AS WELL AS DAMAGING WINDS GIVEN THE STRONG WINDS ALOFT
 AND RELATIVELY DRY AIR NEAR THE SURFACE. THUNDERSTORMS WILL
 GRADUALLY BUILD TOWARD THE NORTH AND EAST OVERNIGHT...WITH A
 CONTINUED RISK FOR HAIL AND DAMAGING WINDS.

 A SECONDARY AREA OF THUNDERSTORMS IS EXPECTED TO DEVELOP OVER
 NORTHERN KANSAS THIS EVENING...AND MAY ORGANIZE INTO A THUNDERSTORM
 COMPLEX AS IT TRACKS INTO FAR NORTHEAST KANSAS AND NORTHWEST
 MISSOURI AFTER MIDNIGHT. THIS ACTIVITY WILL ALSO SUPPORT A
 THREAT OF DAMAGING WINDS AND LARGE HAIL...ALONG WITH LOCALLY HEAVY
 RAINFALL IN AREAS NORTH OF HIGHWAY 36.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

 THUNDERSTORMS ARE EXPECTED ACROSS THE REGION SUNDAY NIGHT THROUGH
 TUESDAY. OVERALL CONDITIONS ARE BECOMING INCREASINGLY FAVORABLE FOR
 ONE OR TWO ROUNDS OF SEVERE WEATHER ACROSS THE OUTLOOK AREA MONDAY
 AND TUESDAY. PERSONS SHOULD STAY TUNED TO LATER OUTLOOKS ON THIS
 DEVELOPING STORM.

.SPOTTER INFORMATION STATEMENT...

 SPOTTER ACTIVATION MAY BE REQUIRED ALONG AND NORTH OF THE MISSOURI
 RIVER...MAINLY AFTER 8 PM.

DEROCHE/BOOKBINDER

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