Damaging Wind in Kansas, August 12, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DODGE CITY KS
315 PM CDT THU AUG 11 2011

.DISCUSSION...

DAYS 1-2...

THE MAIN FORECAST CHALLENGES ARE CHANCES FOR SEVERE THUNDERSTORMS
TONIGHT AND AGAIN FRIDAY AFTERNOON AND EVENING.

A NORTHERN BRANCH SHORTWAVE TROUGH MOVING INTO THE DAKOTAS AND AN
IMPULSE MOVING INTO THE COLORADO ROCKIES WILL FAVOR STRONG TO SEVERE
THUNDERSTORMS TO DEVELOP. A LARGE CLUSTER OF STORMS WILL BEGIN IN
EASTERN COLORADO LATE THIS AFTERNOON AND MOVE INTO WESTERN KANSAS
EARLY THIS EVENING WITH STRONG FLOW OF 60 TO 70KTS AT 200MB. SHORT
RANGE AND MESOSCALE MODELS WEAKEN THE STORMS AS THEY MOVE ACROSS
SOUTHWESTERN KANSAS EXCEPT FOR THE GFS. INCREASING UPSLOPE MOISTURE
AND INCREASING LOW LEVEL JET BY 06Z SHOULD FAVOR THE CONTINUATION OF
A MARGINALLY SEVERE CLUSTER OF THUNDERSTORMS. THE BEST CHANCE FOR
SEVERE WILL BE IN OUR WESTERN FA THIS EVENING AND STORMS MAY SEND
OUT OUTFLOW WINDS AND COLLAPSE AS THEY MOVE EAST. HOWEVER WILL KEEP
20 TO 30 POPS GOING TO COVER. HAIL UP TO GOLFBALL SIZE IS POSSIBLE
MAINLY IN THE WEST FA THIS EVENING. THE SHORTWAVE TROUGH WILL PUSH A
SURFACE TROUGH INTO WESTERN KANSAS TONIGHT WITH SOUTHEAST TO SOUTH
WINDS WITH MILD OVERNIGHT LOWS IN THE UPPER 60S TO AROUND 70.

FOR FRIDAY THE NORTHERN BRANCH SHORTWAVE TROUGH WILL DIVE
SOUTHEASTWARD INTO THE UPPER MIDWEST SENDING A COLD FRONT INTO THE
FA IN THE MID TO LATE AFTERNOON. STRONG LAYER SHEAR AND CAPES AROUND
3000 J/KG WILL SUPPORT SEVERE THUNDERSTORMS ALONG THE COLD FRONT
WITH THE BEST CHANCES EAST OF A LINE FROM HAYS TO DODGE CITY AND
LIBERAL BY MID AFTERNOON THEN SOUTH INTO THE EVENING. STRONG
DAMAGING WINDS AND HAIL GREATER THAN GOLFBALL SIZE IS POSSIBLE. HIGH
TEMPERATURES WILL BE AROUND 100 SOUTH OF THE FRONT NEAR THE OKLAHOMA
BORDER AND AROUND 90 IN THE NORTH FA. OVERNIGHT LOWS WILL BE A
LITTLE COOLER IN THE LOW TO MID 60S.

ON SATURDAY COOLER HIGH PRESSURE WILL BUILD INTO THE CENTRAL PLAINS
BEHIND THE COLD FRONT AND UPSLOPE MOISTURE IN THE FAR SOUTHWEST FA
MAY SET OFF A FEW THUNDERSTORMS LATE IN THE AFTERNOON. HIGHS LOOK TO
BE AROUND 90.

DAYS 3-7...

THE EXTENDED PERIOD BEGINS 00Z SUNDAY. THE HIGHEST POPS - CHANCE
POPS - ARE EXPECTED ACROSS THE WESTERN COUNTIES SATURDAY EVENING.
THE UPPER LEVEL FLOW IS QUITE AMPLIFIED WITH AN UPPER LEVEL TROUGH
DIGGING ACROSS THE GREAT LAKES STATES. THIS RESULTS IN NORTHWEST
FLOW ALOFT OVER KANSAS. AT THE SURFACE, UPSLOPE FLOW IS EXPECTED IN
THE WAKE OF A PASSING FRONT. SUCH AS CONFIGURATION FAVORS CONVECTION
FORMING ALONG THE HIGHER COLORADO TERRAIN AND THEN WITH STORMS
DRIFTING INTO WESTERN KANSAS. AS SUCH, THE POP CONFIGURATION IN THE
GRIDS REFLECTS SUCH THINKING.

ON SUNDAY, UPPER LEVEL FLOW BECOMES A BIT MORE WESTERLY. WITH A
CONTINUED LOW LEVEL WARM AIR ADVECTION REGIME IN PLACE ACROSS THE
HIGH PLAINS, THINK CONVECTION COULD STILL FORM IN COLORADO. HAVE
EXPANDED POPS TO THE EAST WITH CHANCE POPS COVERING A BIGGER PORTION
OF THE CWFA. THE ECMWF SHOWS THE 850 LOW LEVEL JET STRENGTHENING IN
THE LEE OF THE ROCKIES TO AROUND 30 KNOTS SUNDAY EVENING. THINK WITH
WITH SURFACE DEWPOINTS IN THE 60S AND WITH WAA/ISENTROPIC LIFT,
STORMS WILL REMAIN SUCH A POSSIBILITY AGAIN.

MONDAY THE FORECAST BECOMES A BIT MORE CONVOLUTED AS THE GFS SHOWS
A SURFACE TROUGH AXIS MOVING ACROSS WESTERN KANSAS WHEREAS THE ECMWF
IS A BIT SLOWER. STILL HAVE SLIGHT POPS DURING THIS PERIOD WITH THE
HIGHEST TO THE NORTH WHERE THIS REGION WILL BE CLOSER TO UPPER LEVEL
JET DYNAMICS AND VORT MAXES ROTATING AROUND A SHORTWAVE TROUGH
MOVING THROUGH MONTANA AND EVENTUALLY THE NORTHERN PLAINS.

WEDNESDAY AND THURSDAY THE FORECAST DRIES OUT AND WARMS UP AS MID
LEVEL 500 HPA RIDGE MOVES CLOSER TO KANSAS FRONT THE SOUTHERN PLAINS
AND DOMINATES MORE ON THE SYNOPTIC SCALE.

AS FAR AS TEMPERATURES ARE CONCERNED, UPPER 80S TO LOWER 90S LOOK
REASONABLE AND USED CONSALL ALL AND BLENDING TECHNIQUES FOR THE T
GRIDS. WARMED UP TEMPERATURES TOWARDS THE END OF THE NEXT BUSINESS
WEEK DUE TO THE INFLUENCE OF THE AFOREMENTIONED UPPER LEVEL RIDGE.
-SUGDEN

&&

.AVIATION...

THE FORECAST PROBLEM OF THE DAY IN THE TAF WORLD WAS DO DECIDE ABOUT
THE PROSPECTS FOR CONVECTION THROUGH THE 18Z TAF CYCLE. RIGHT NOW
THE MODELS ARE ALL OVER THE PLACE AS FAR AS CONVECTIVE INITIATION IS
CONCERNED. THE NAM FORMS CONVECTION ACROSS NORTH CENTRAL COLORADO
AND THEN WEAKENS IT INTO NORTHWESTERN KANSAS TOWARDS GOODLAND. THE
GFS IS A BIT MORE AGGRESSIVE WITH STORMS DEVELOPING ACROSS NE
COLORADO AND INTO SW NEBRASKA AND THEN SPREADS THE MCS INTO SC
KANSAS. THE WRF IS A BIT LIKE THE GFS EXPECT FURTHER SOUTH TOWARDS
DODGE CITY. THE ECMWF IS THE MIDDLE MAN WHILE THE GEM HAS NOTHING AT
ALL. HAVE DECIDED TO PLAY IT SAFE AND IN THE MIDDLE WITH INTRODUCING
A VFR CLOUD DECK THIS EVENING FOR THE TERMINALS BUT NOT BRINGING IN
VCTS/RA OR CB GROUPS AS I DON'T HAVE ENOUGH CONFIDENCE ON CONVECTIVE
EVOLUTION THIS EVENING AND THE 00Z TAFS/GUIDANCE MIGHT HAVE A BETTER
HANDLE ON THE SITUATION THAN COMPARED TO 12Z DATA. -SUGDEN

&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  68  97  65  91 /  20  30  30  10
GCK  67  96  64  91 /  20  20  20  10
EHA  67  98  65  88 /  20  20  20  20
LBL  67 100  65  90 /  20  20  30  20
HYS  67  90  62  88 /  30  30  20  10
P28  71  99  69  93 /  30  30  40  10

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

FN06/36/36

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE DODGE CITY KS
336 PM CDT THU AUG 11 2011

KSZ030-031-043>046-061>066-074>081-084>090-122045-
TREGO-ELLIS-SCOTT-LANE-NESS-RUSH-HAMILTON-KEARNY-FINNEY-HODGEMAN-
PAWNEE-STAFFORD-STANTON-GRANT-HASKELL-GRAY-FORD-EDWARDS-KIOWA-
PRATT-MORTON-STEVENS-SEWARD-MEADE-CLARK-COMANCHE-BARBER-
336 PM CDT THU AUG 11 2011 /236 PM MDT THU AUG 11 2011/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL...SOUTH
CENTRAL...SOUTHWEST AND WEST CENTRAL KANSAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT

SCATTERED THUNDERSTORMS WILL MOVE INTO SOUTHWEST KANSAS THIS
EVENING FROM COLORADO. SOME OF THESE MAY BE SEVERE MAINLY WEST OF
A LINE FROM DIGHTON TO GARDEN CITY AND LIBERAL. WINDS OVER 70 MPH
AND HAIL TO GOLFBALL SIZE ARE POSSIBLE. AS THEY PROGRESS EASTWARD
OVERNIGHT THEY MAY WEAKEN AND PRODUCE SOME STRONG OUTFLOW WINDS
GREATER THAN 50 TO 60 MPH.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

MORE SEVERE THUNDERSTORMS ARE POSSIBLE AGAIN ON FRIDAY AFTERNOON
AND EVENING AS A COLD FRONT MOVES ACROSS SOUTHWEST AND SOUTH
CENTRAL KANSAS. STRONG AND DAMAGING WINDS OVER 70 MPH AND HAIL
GREATER THAN GOLFBALL SIZE ARE POSSIBLE MAINLY EAST OF A LINE FROM
HAYS TO DODGE CITY AND LIBERAL.

SCATTERED THUNDERSTORMS ARE POSSIBLE LATE SATURDAY AFTERNOON IN
FAR SOUTHWEST KANSAS INTO SATURDAY EVENING. MORE SCATTERED
THUNDERSTORMS ARE POSSIBLE ACROSS SOUTHWEST AND SOUTH CENTRAL
KANSAS SUNDAY AFTERNOON INTO SUNDAY NIGHT. IT IS TOO EARLY TO
DETERMINE IF ANY OF THESE STORMS WILL BE SEVERE.

.SPOTTER INFORMATION STATEMENT...

A FEW STORM SPOTTERS MAY BE NEEDED THIS EVENING MAINLY WEST OF A
LINE FROM DIGHTON TO GARDEN CITY AND LIBERAL.

&&

FOR MORE INFORMATION VISIT OUR WEBPAGE AT HTTP://WEATHER.GOV/DDC

06