Severe Thunderstorm Warning 218, NWS Kansas City, MO

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
625 PM CDT MON JUL 21 2008

...UPDATED AVIATION DISCUSSION...

.DISCUSSION...

SHORT RANGE (TODAY THROUGH WEDNESDAY)...

ACTIVE WEATHER THAT HAS BEEN FOCUSED TO OUR NORTH FOR THE PAST
COUPLE OF NIGHT WILL FINALLY BEGIN TO IMPACT OUR AREA TONIGHT AS A
FRONT SETTLES SOUTH. IMPRESSIVE BOW ECHO ACROSS CENTRAL IOWA
OVERNIGHT LEFT SEVERAL STRONG OUTFLOW BOUNDARIES MOVING SOUTH ACROSS
THE CWA THIS MORNING. MORE IMPORTANTLY THE SURFACE FRONT TO OUR
NORTH GOT SHOVED INTO NORTHERN MISSOURI A BIT MORE QUICKLY THAN
PREVIOUSLY FORECAST...AND HAS BEEN HANGING OUT JUST SOUTH OF THE
IOWA BORDER THIS AFTERNOON AS A SURFACE LOW SPINS UP ALONG IT IN THE
IA/NE/MO TRI-STATE AREA. FARTHER NORTH...WATER VAPOR IMAGERY SHOWS A
SHORTWAVE MOVING SOUTH SOUTHEAST FROM MANITOBA THROUGH THE DAKOTAS
TOWARDS IOWA IN THE INCREASINGLY MERIDIONAL FLOW ACROSS THE NORTHERN
PLAINS.

AFTERNOON ANALYSIS INDICATES THAT MLCAPE VALUES HAVE CLIMBED TO OVER
4500 J/KG JUST SOUTH OF THE FRONT...IN THE ST JOSEPH TO CHILLICOTHE
AREAS...WITH ONLY A MARGINAL CAP STILL LEFT IN PLACE. LACK OF STRONG
CONVERGENCE ALONG THE SURFACE FRONT...THE MODEST CAP...AND DEFICITS
IN MOISTURE DUE TO THE OUTFLOW THAT MOVED THROUGH EARLY THIS
MORNING...HAS THUS FAR LIMITED CU AND CONVECTIVE DEVELOPMENT. MID
AND HIGH LEVEL CLOUD COVER ACROSS NEBRASKA AND IOWA THIS AFTERNOON
LOOKS TO BE IN RESPONSE TO THE H3 JET AND NOT ANY NEAR BY SHORTWAVE.
STILL...THE WAVE HEADING SOUTH SOUTHEAST INTO IOWA THIS AFTERNOON
MIGHT ENHANCE CONVERGENCE AND DYNAMICS JUST ENOUGH TO SPARK
CONVECTION LATE THIS AFTERNOON/EARLY THIS EVENING ACROSS NORTHWEST
MISSOURI. WHILE CURRENTLY ANALYZED 0-6KM SHEAR VALUES ARE RATHER
MINIMAL SOUTH OF THE MISSOURI BORDER...EXPECTATIONS ARE THAT THEY
WILL INCREASE TO BETWEEN 30 AND 40 KNOTS LATE THIS AFTERNOON AS THE
SHORTWAVE DROPS INTO IOWA. WITH INITIATION STILL VERY POSSIBLE IN
THE VICINITY OF THE SURFACE LOW IN THE TRI-STATE AREA...INITIAL
MODE  FOR CONVECTION COULD START AS SUPERCELLS...WITH A STORM MOTION
TO THE EAST SOUTHEAST. THESE STORMS WOULD BE EXPECTED TO CONGEAL
INTO A PROGRESSIVE LINER MCS AS THEY MOVE FARTHER EAST. THIS
SCENARIO WOULD MAKE THE PRIMARY SEVERE THREAT DAMAGING STRAIGHT-LINE
WINDS THROUGHOUT THE EVENT...BUT LARGE HAIL AND VERY ISOLATED THREAT
OF TORNADOES WILL BE POSSIBLE IN THE NORTHWEST CORNER OF MISSOURI AS
THE FIRST INITIAL INDIVIDUAL THUNDERSTORMS SPIN UP IN THE VICINITY
OF THE SURFACE LOW AND/OR CROSS THE FRONTAL BOUNDARY. HOWEVER...WITH
ALL THIS SAID TIMING OF INITIATION IS STILL A BIT NEBULOUS AS VERY
LITTLE IN THE WAY OF CUMULUS CLOUD COVER HAS POPPED UP YET...THUS
INDICATING A CONTINUED LACK OF SUFFICIENT MOISTURE...OR LIFT.
STILL...IF THINGS GET GOING THEY WILL GO FAST DUE TO ABUNDANT
INSTABILITY. WILL THEREFORE CONTINUE TO GO WITH CHANCE POPS LATE
THIS AFTERNOON ALONG THE IOWA BORDER...AND LEAVE THE LIKELY POPS FOR
THE AFTER 00Z TIME FRAME. WITH A STRONG THETA-E GRADIENT ACROSS THE
NORTHERN SIDE OF THE CWA ALL NIGHT...AND AT LEAST A MINIMAL 20  TO
25 KNOT LOW LEVEL JET...STORMS COULD PERCOLATE ALONG FOR MUCH OF THE
NIGHT...SO WILL LEAVE THE LIKELY POPS IN ALL NIGHT.

DEEPENING EAST CONUS TROUGH AND THE RESULTING MERIDIONAL FLOW SHOULD
SHOVE THE FRONT INTO CENTRAL MISSOURI BY TUESDAY MORNING...BUT THE
WEST CONUS RIDGE SHOULD KEEP IT FROM MAKING IT MUCH FARTHER SOUTH OR
WEST. THIS WILL LEAVE AN UNSEASONABLY STRONG BAROCLINIC ZONE
WALLOWING OVER MISSOURI TUESDAY AND WEDNESDAY...PROVIDING A RATHER
LARGE TEMPERATURE GRADIENT FROM THE SOUTHWEST TO NORTHEAST ACROSS
THE CWA...AND A FOCUS FOR MORE CONVECTION OVER THE FOLLOWING TWO
DAYS. HAVE LEFT A GOING 40% CHANCE POP IN FOR TOMORROW BANKING ON
LEFT OVER CONVECTION STILL LINGERING AROUND IN THE MORNING...WITH
REDEVELOPMENT ALONG THE BOUNDARY IN THE HEAT OF THE AFTERNOON.
WEDNESDAY WILL SEE THE FOCUS OF POTENTIAL CONVECTION SHIFT A LITTLE
FARTHER SOUTHWEST...THOUGH STILL PREVAIL ACROSS AT LEAST HALF THE
FORECAST AREA.

CUTTER

MEDIUM RANGE (THURSDAY THROUGH MONDAY)...

FORECAST DETAILS REMAIN VERY DIFFICULT TO PIN DOWN AS WE HEAD TOWARD
THE END OF THE WORK WEEK AND THROUGH NEXT WEEKEND...WITH MANY
DETAILS HIGHLY DEPENDENT ON OUTCOME OF THE NEXT TWO DAYS.
ATMOSPHERE WILL LIKELY REMAIN IN A VERY ACTIVE PHASE DURING
THE MEDIUM RANGE...DUE IN PART TO AN ABNORMALLY STRONG UPR TROUGH
BASED IN THE EASTERN GREAT LAKES.  THIS TROUGH WILL CONTINUE TO KEEP
CLIMATOLOGICALLY FAVORABLE H500 RIDGE FROM BUILDING INTO THE CENTRAL
CONUS.  THE END RESULT WILL BE A CONTINUATION OF MID-LVL IMPULSES
WHICH COULD CONTINUE A RATHER ACTIVE MCS SEASON OVER THE MID
MISSOURI VALLEY.

FOR THURSDAY...LEAD SHORTWAVE IS EXPECTED TO LIFT NORTHWARD ALONG
THE PERIPHERY OF THE MID-LVL RIDGE AXIS...PULLING H850 THETA-E AXIS
NEWRD ALONG WITH IT.  LATEST OPER GFS HAS ARRIVED AT A SIMILAR
TIMING WITH THAT OF THE ECMWF...DEVELOPING MCS WELL TO THE NW ALONG
THE AXIS BY WED NIGHT AND DROPPING IT SE ALONG THE MOISTURE AXIS IN
THE DAY.  HAVE INCREASED POPS OVER THE WESTERN TWO THIRDS OF THE CWA
ON THU/THU NIGHT.  TEMPERATURES WILL ALSO BE PROBLEMATIC AS THE
POTENTIAL EXISTS FOR A WIDE RANGE OF VALUES FROM WEST TO EAST. RIGHT
NOW AM BANKING ON EML LIFTING INTO THE WESTERN CWA BY EARLY THU
AFTN...WHICH SHOULD SCATTERED OUT CLOUDS AND ALLOW TEMPERATURES TO
REACH INTO THE LOW 90S LATE IN THE AFTERNOON. A MUCH MORE TRICKY
FORECAST EXISTS FURTHER EAST...AS TIMING REMAINS THE BIGGEST ISSUE
ATTM.

FOR FRIDAY AND INTO EARLY NEXT WEEK...MODELS TYPICALLY HAVE A HARD
TIME RESOLVING SYNOPTIC DETAILS AFTER DAY 5 GIVEN THE CURRENT FLOW
REGIME.  THIS IS CLEARING BECOMING EVIDENT IN THE WILD ARRAY OF
MODEL SOLUTIONS BEING PRESENTED WITH VARYING DEGREES OF DIFFERENCE
ALREADY NOTED IN THE LONG WAVE FEATURES.  NEVERTHELESS...NO STRONG
FEELING TO DIFFER WIDELY FROM THE CLIMATOLOGICAL AVERAGE
TEMPERATURES RANGE INTO NEXT WEEK. AS FAR AS PRECIPITATION IS
CONCERNED...WITH SO MANY UNCERTAINTIES OUT THERE AND LOW CONFIDENCE
IN GENERAL...HARD TO PINPOINT ANY ONE TIME PERIOD FOR POPS HIGHER
THAN A SLIGHT CHC CAT.  HOWEVER ONE TIME PERIOD TO FOCUS ON FOR A
BETTER CHANCE OF PRECIP LOOKS TO ARRIVE BY SAT NIGHT INTO SUNDAY AS
NEXT WEAK FRONT APPROACHES FROM THE NORTH.

DUX

&&

.AVIATION...

FOR THE 00Z TAFS...FOR THE MOST PART KEPT CEILINGS IN THE VFR RANGE
FOR THE TERMINALS THROUGH THE NEXT 24 HOURS. THE EXCEPTION IS THE
TEMPO FOR MVFR CIGS AND THUNDERSTORMS IN KSTJ AND A PROB30 AT KMCI
AND KMKC...FOR STORMS THAT COULD MOVE THROUGH OVERNIGHT.
HOWEVER...THERE IS A HIGH DEGREE OF UNCERTAINTY WITH THE TIMING.
OTHERWISE...SURFACE WINDS WILL ADJUST TO THE WEST OVERNIGHT AS THE
FRONT MOVES SOUTH.

CUTTER

&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
102 PM CDT MON JUL 21 2008

KSZ025-057-060-102>105-MOZ001>008-011>017-020>025-028>033-037>040-
043>046-053-054-221100-
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-
102 PM CDT MON JUL 21 2008

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

A HOT AND HUMID AIRMASS WILL REMAIN IN PLACE OVER MUCH OF THE REGION
THIS AFTERNOON. TEMPERATURES IN THE 90S...ALONG WITH THE
HUMIDITY...WILL CONTRIBUTE TO HEAT INDICES BETWEEN 100 AND 105
DEGREES ALONG AND SOUTH OF A LINE FROM ST JOSEPH TO MOBERLY. PERSONS
SHOULD AVOID PROLONGED OUTDOOR EXPOSURE TO THE HEAT.

THIS AIRMASS WILL ALSO CONTRIBUTE TO STRONG INSTABILITY THAT WILL
SET THE STAGE FOR SEVERE THUNDERSTORMS LATE THIS AFTERNOON AS A
BACKDOOR COLD FRONT SETTLES SOUTH FROM IOWA. UNSEASONABLY STRONG WIND
SHEAR WILL ALLOW A FEW SUPERCELL THUNDERSTORMS TO DEVELOP INITIALLY
OVER FAR NORTHWEST MISSOURI...WITH THE POSSIBILITY OF LARGE
HAIL...DAMAGING WINDS...AND EVEN AN ISOLATED TORNADO. THESE STORMS
ARE EXPECTED TO ORGANIZE THIS EVENING...WITH DAMAGING WINDS THE MAIN
THREAT AS THIS COMPLEX RACES SOUTHEAST ACROSS CENTRAL AND NORTHERN
MISSOURI. LOCATIONS ALONG AND NORTH OF A LINE FROM ST JOSEPH TO
FAYETTE WILL HAVE THE GREATEST CHANCE FOR STRONG TO SEVERE
THUNDERSTORMS THROUGH DAYBREAK TUESDAY.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

STRONG TO SEVERE THUNDERSTORMS MAY BE ONGOING EARLY TUESDAY...WITH
CONVECTIVE REDEVELOPMENT ALONG THE FRONT DURING THE AFTERNOON HOURS
OF TUESDAY.

ADDITIONAL THUNDERSTORM COMPLEXES ARE EXPECTED TO PLAGUE MUCH OF THE
OUTLOOK AREA WEDNESDAY THROUGH THURSDAY AS THE BACKDOOR COLD FRONT
EVENTUALLY STALLS ALONG THE MISSOURI AND KANSAS BORDER.

SEVERE WEATHER CANNOT BE RULED OUT WITH ANY OF THESE COMPLEXES THIS WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL LIKELY BE NEEDED ACROSS NORTHERN MISSOURI
AFTER 4 PM.

CUTTER

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