Severe Thunderstorm Warning 309, NWS Goodland, KS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GOODLAND KS
212 PM MDT FRI SEP 24 2004

.SHORT TERM...(TONIGHT THROUGH MONDAY)
THUNDERSTORM CHANCES WILL BE THE FORECAST PROBLEM.

WEAK CYCLONIC FLOW AT 500 MB TO SLOWLY SINK SOUTH THROUGH THE
WEEKEND...CONTRIBUTING TO MODERATE LAPSE RATES. 700 MB CHARTS SHOW
ANTICYCLONE TO REMAIN NEARLY STATIONARY OVER SOUTH CENTRAL KANSAS.
FLOW AROUND THIS FEATURE WILL BRING PERIODIC VORTICITY MAXIMUMS OVER
THE AREA FROM THE SOUTHWEST. ONE SUCH VORT MAX CURRENTLY OVER
SOUTHEAST COLORADO WILL SUPPORT THE DEVELOPMENT OF A WEAK SURFACE
LOW WHICH DRIFTS NORTHWARD TONIGHT. THUNDERSTORMS RAPIDLY DEVELOPING
IN THIS AREA WITH FALLING PRESSURES AT SPRINGFIELD COLORADO SUPPORT
THIS SCENARIO. RUC SEEMS TO BE HANDLING BEST...SO WILL HAVE LIKELY
POPS TONIGHT IN THE EXTREME SOUTHWEST ZONES TO SLIGHT CHANCES FAR
NORTHEAST. ON SATURDAY THE SHEARED OUT 700 MB VORTICITY MAXIMUM WILL
SPREAD ACROSS THE ENTIRE FORECAST AREA. SURFACE WIND FIELD FORECAST
BY THE RUC SHOWS A WEAK CYCLONIC CONVERGENCE LINE FROM SOUTHWEST TO
NORTHEAST ACROSS THE HEART OF THE FORECAST AREA. ALTHOUGH LOW LEVEL
MOISTURE WILL BE LIMITED...APPEARS TO BE ENOUGH SUBTLE LIFTING
MECHANISMS IN PLACE TO WARRANT A MENTION OF THUNDERSTORMS. THE
PATTERN DOES NOT CHANGE MUCH ON SUNDAY...OTHER THAN TO SHIFT
SLIGHTLY SOUTH WITH 500 MB TROUGH AXIS. FOR THIS REASON WILL KEEP
SLIGHT MENTION IN THE FORECAST...EXCEPT FAR NORTHWEST CORNER.

&&

.LONG TERM...(TUESDAY THROUGH FRIDAY)
SHORTWAVE IN WESTERLIES ACROSS CENTRAL CANADA WILL DIG INTO THE
NORTHERN PLAINS/WESTERN GREAT LAKES ON MONDAY. ASSOCIATED SURFACE
COLD FRONT WILL MOVE THROUGH THE FORECAST AREA MONDAY
AFTERNOON/EVENING. THIS IS SLIGHTLY FASTER THAN PREVIOUS RUNS...BUT
MOST OF THE GLOBAL MODELS ARE COMING AROUND TO THIS TIMING.
TEMPERATURE IMPACTS WITH THIS FRONT WILL BE MINIMAL AS ONLY A
GLANCING BLOW EXPECTED. IN FACT...RETURN FLOW AROUND THE SURFACE
HIGH WILL QUICKLY SET UP ON TUESDAY. GFS/DGEX/ECMWF FORECAST
SOUTHERLY LOW LEVEL JET TO DEVELOP TUESDAY NIGHT...AND AM CONCERNED
THIS WILL SUPPORT A NOCTURNAL THUNDERSTORM EVENT ACROSS THE FORECAST
AREA. DIFFICULT TO PIN DOWN THE DETAILS AT THIS POINT...AND WILL LET
SLIGHT CHANCE POPS SUFFICE FOR NOW. WEDNESDAY AND THURSDAY EXPECT
UPPER LEVEL RIDGING AHEAD OF THE CUT OFF LOW OVER THE DESERT
SOUTHWEST. HOW FAST THIS SYSTEM LIFTS INTO THE CENTRAL ROCKIES
REPRESENTS THE GREATEST DIFFERENCE AMONG THE VARIOUS MODELS...WITH
THE GFS/DGEX SLOWEST...AND THE CANADIAN GLOBAL/ECMWF FASTEST.
SPLITTING THE DIFFERENCE BETWEEN THESE SOLUTIONS WAS THE RATIONALE
FOR INCLUDING SLIGHT CHANCE OF THUNDERSTORMS ON DAY 7.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
NE...NONE.
CO...NONE.

&&

JDK

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GOODLAND KS
159 PM MDT FRI SEP 24 2004

COZ090>092-KSZ001>004-013>016-027>029-041-042-NEZ079>081-251200-
CHEYENNE KS-CHEYENNE COUNTY CO-DECATUR KS-DUNDY NE-GOVE KS-GRAHAM KS-
GREELEY KS-HITCHCOCK NE-KIT CARSON COUNTY CO-LOGAN KS-NORTON KS-
RAWLINS KS-RED WILLOW NE-SHERIDAN KS-SHERMAN KS-THOMAS KS-WALLACE KS-
WICHITA KS-YUMA COUNTY CO-
200 PM MDT FRI SEP 24 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHWEST KANSAS...EXTREME
SOUTHWEST NEBRASKA...AND EAST CENTRAL COLORADO.

.DAY ONE...THIS AFTERNOON AND TONIGHT

THE ATMOSPHERE HAS RAPIDLY DESTABILIZED EARLY THIS AFTERNOON IN THE
EXTREME SOUTHWEST SECTION OF THE TRISTATE AREA AS A BAND OF MOIST AIR
HAS MOVED NORTHWARD ALONG THE KANSAS AND COLORADO BORDER. AS A RESULT
THE AREA FOR POSSIBLE AFTERNOON AND EVENING THUNDERSTORMS HAS BEEN
EXPANDED TO INCLUDE THOSE AREAS SOUTH AND WEST OF A LINE FROM YUMA
COLORADO TO BURLINGTON TO SHARON SPRINGS TO THE MONUMENT ROCKS AREA
OF GOVE COUNTY KANSAS. SMALL HAIL...CLOUD TO GROUND LIGHTNING AND
WIND GUSTS TO 40 MPH ARE POSSIBLE WITH THESE THUNDERSTORMS.

SOUTH AND WEST OF A LINE FROM FLAGLER COLORADO TO CHEYENNE WELLS TO
LEOTI KANSAS...WHERE THE MOST UNSTABLE AIR HAS REACHED...THERE IS A
SLIGHT CHANCE THAT A FEW STORMS MAY BECOME SEVERE. LARGE HAIL...BRIEF
HEAVY DOWNPOURS AND DAMAGING WINDS GUSTING TO 60 MPH WOULD BE THE
GREATEST THREATS IN THOSE STORMS.

THUNDERSTORM ACTIVITY IS EXPECTED TO LAST THROUGH THE EVENING HOURS
BEFORE BEGINNING TO DISSIPATE.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THUNDERSTORMS WILL AGAIN BE POSSIBLE MONDAY AND TUESDAY AFTERNOON AND
EVENING DUE TO THE PASSAGE OF WEAK COLD FRONT. THE BEST CHANCE FOR
THUNDERSTORMS WILL BE MONDAY NIGHT. THE STORMS ARE NOT EXPECTED TO BE
SEVERE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED LATE THIS AFTERNOON AND EVENING
SOUTH OF A CHEYENNE WELLS TO LEOTI LINE.

RJC