Tornadoes and Flash Flood in Kansas, June 26, 2004

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GOODLAND KS
202 PM MDT SAT JUN 26 2004

.SHORT TERM...(TONIGHT THROUGH TUESDAY)
SHOWER AND THUNDERSTORM ACTIVITY THIS AFTERNOON PRIMARILY THE RESULT
OF 700 MB VORTICITY MAXIMUM WHICH AT 18Z WAS NEAR YUMA COLORADO. THE
SPIN IS CLEARLY EVIDENT ON VISIBLE SATELLITE IMAGERY. THE FEATURE
PROGGED BY RUC/MESOETA/WRF TO DRIFT EAST/SOUTHEAST ACROSS THE
FORECAST AREA THIS AFTERNOON AND TONIGHT. FURTHER WEST...SIGNIFICANT
CLEARING HAS OCCURRED OVER THE FRONT RANGE AND ADJACENT PLAINS OF
COLORADO...AND DAYTIME HEATING HAS INITIATED CONVECTION.
HOWEVER...RELATIVELY WEAK MID LEVEL WINDS MAY LIMIT SEVERE POTENTIAL
WITH THESE STORMS AS THEY DRIFT SOUTHEASTWARD THIS EVENING.
SO...BEST CHANCES FOR PRECIPITATION WILL BE OVER SOUTHERN AND
EASTERN ZONES...MAINLY THIS EVENING...ASSOCIATED WITH THE 700 MB
VORTICITY MAXIMUM...WHILE CHANCE POPS WILL BE NEEDED IN EASTERN
COLORADO AS WELL FOR THE MOUNTAIN INDUCED CONVECTION. BOTH AREAS
EXPECTED TO DIMINISH/BE SOUTH OF THE AREA AFTER 06Z.

SUNDAY...POTENT SHORTWAVE WILL DROP THROUGH THE NORTHERN PLAINS IN
NORTHWEST FLOW. ETA AGGRESSIVELY BRINGING A BOUNDARY INTO THE
FORECAST AREA DURING THE AFTERNOON ASSOCIATED WITH THIS FEATURE AND
DEVELOPING CONVECTION ALONG IT. RUC/GFS/UKMET SHOW ONLY A WEAK
CONVERGENCE ZONE IN THE SURFACE WIND FIELD...IN NEBRASKA. ALL MODELS
FORECAST UPSLOPE FLOW AND MOIST DEW POINTS IN THE 50S...SO ANY
SURFACE HEATING THAT CAN TAKE PLACE MAY INITIATE SHOWERS AND
THUNDERSTORMS. HOWEVER...ONLY MODEST INSTABILITY AND WEAK SHEAR
FORECAST OVER THE AREA...SO SEVERE THREAT SEEMS MINIMAL. WILL HAVE
CHANCE POPS ACROSS THE NORTH TAPERING TO SLIGHT CHANCE ACROSS THE
SOUTH WITH BOUNDARY APPROACHING SLOWER THAN ETA FORECAST. GFS
SUFFERING FROM CONVECTIVELY INDUCED VORTICITY MAXIMUM OVER
NORTHEASTERN COLORADO SUNDAY NIGHT...BUT STILL SHOULD SEE SOME
STORMS ROLLING OUT OF COLORADO INTO THE WESTERN ZONES WITH DAYTIME
HEATING OVER THE MOUNTAINS.

MONDAY AND TUESDAY...ZONAL TO NORTHWESTERLY FLOW ALOFT WITH EASTERLY
UPSLOPE FLOW AT THE SURFACE WILL FAVOR AFTERNOON THUNDERSTORM
DEVELOPMENT OVER COLORADO...MOVING EAST INTO KANSAS AND NEBRASKA
DURING THE EVENING. DIRECTIONAL SHEAR WILL BE MAXIMIZED...BUT 500 MB
WINDS SPEEDS FORECAST TO BE LESS THAN 30 KTS BOTH DAYS...WHICH
SHOULD LIMIT SEVERE RISK. OF THE TWO...TUESDAY HAS THE BETTER
POTENTIAL BASED ON FORECAST CAPE VALUES FROM THE ETA OF 1000-1500
J/KG...THOUGH ETA HAS NOT DONE WELL AS OF LATE WITH INSTABILITY
FORECASTS. EXPECT GRADUAL TEMPERATURE RISE BASED ON 850 MB
TEMPERATURES BUT DID NOT GET TOO CARRIED AWAY WITH UPSLOPE SURFACE
WINDS ON TAP.

&&

.LONG TERM...(WEDNESDAY THROUGH SATURDAY)
THE OVERALL PATTERN CHANGES LITTLE DURING THE EXTENDED PERIOD.
RIDGING GENERALLY IN PLACE OVER THE ROCKIES FROM CANADA TO
MEXICO...WITH NORTHERN STREAM LOW HEIGHT CENTERS ANCHORED OVER THE
GULF OF ALASKA AND NEAR HUDSON BAY. A SOUTHERN STREAM DISTURBANCE
WILL BE NEARLY STATIONARY OFF THE SOUTHERN CALIFORNIA COAST...AND
WILL EJECT ENERGY THROUGH THE RIDGE LATE IN THE WEEK. THE SYSTEM
WILL HAVE SOME UPPER SUPPORT AS WELL FROM A SOUTHERN STREAM JET
STREAK COMING UP FROM BAJA CALIFORNIA. 700 MB HEIGHT FIELDS SHOW THE
SYSTEM WILL CLIMB THE WEST SIDE OF THE ROCKIES RIDGE ON WEDNESDAY
AND EJECT INTO THE CENTRAL/NORTHERN PLAINS ON THURSDAY...REACHING
THE MISSOURI/MISSISSIPPI RIVER VALLEYS ON FRIDAY AND SATURDAY. WILL
THEREFORE KEEP SHOWERS/THUNDERSTORMS IN THE FORECAST THROUGH
THURSDAY. VERIFICATION OF OPERATIONAL GFS MOS FORECASTS RECENTLY
SHOWS A CONSISTENT 5 TO 10 DEGREE WARM BIAS IN HIGH
TEMPERATURES...AND GIVEN THE SIMILARITY IN PATTERNS THINK THE MEX
WILL CONTINUE TO BE WARM...ESPECIALLY FOR THE END OF THE EXTENDED
PERIOD...AND WILL LEAN TOWARDS COOLEST OF THE ENSEMBLE MOS MEMBERS.

&&

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

&&

JDK

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GOODLAND KS
123 PM MDT SAT JUN 26 2004

COZ090>092-KSZ001>004-013>016-027>029-041-042-NEZ079>081-271200-
CHEYENNE CO-CHEYENNE KS-DECATUR-DUNDY-GOVE-GRAHAM-GREELEY-HITCHCOCK-
KIT CARSON-LOGAN-NORTON-RAWLINS-RED WILLOW-SHERIDAN-SHERMAN-THOMAS-
WALLACE-WICHITA-YUMA-
123 PM MDT (223 PM CDT) SAT JUN 26 2004

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

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS ARE POSSIBLE ACROSS THE REGION THIS AFTERNOON
AND EVENING. ABUNDANT LOW LEVEL MOISTURE ALONG WITH A WEAK UPPER
LEVEL DISTURBANCE OVER NORTHEAST COLORADO WITH WORK TOGETHER TO
PRODUCE SCATTERED SHOWERS. IN ADDITION TEMPERATURES OVER EASTERN
COLORADO HAVE RISEN WITH HEATING OF THE SUN INTO THE LOW TO MIDDLE
70S. SHOWERS AND THUNDERSTORMS ARE RAPIDLY DEVELOPING OVER THE HIGHER
TERRAIN OF COLORADO AND MOVING EASTWARD. SHOWERS AND THUNDERSTORMS
WILL DEVELOP RAPIDLY OVER THE NEXT HOUR OR SO AND THEN MOVE EASTWARD.
A FEW OF THE THUNDERSTORMS HAVE THE POTENTIAL TO BECOME SEVERE
THROUGH THIS EVENING. THE BEST CHANCE FOR SEVERE STORMS WILL BE
ALONG AND WEST OF A WAUNETA COLORADO TO GOODLAND TO TRIBUNE KANSAS
LINE. THE PRIMARY THREAT WILL BE LARGE HAIL ALONG WITH CLOUD TO
GROUND LIGHTNING.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THUNDERSTORMS WILL BE POSSIBLE AGAIN SUNDAY AFTERNOON AND THROUGH THE
OVERNIGHT HOURS SUNDAY NIGHT. SEVERE WEATHER DOES NOT APPEAR LIKELY
WITH THESE STORMS AS THE AIRMASS SHOULD ONLY BE MODERATELY UNSTABLE.
FOR MONDAY THROUGH THURSDAY THERE WILL BE AT LEAST A SLIGHT CHANCE
OF THUNDERSTORMS EACH DAY...AS A SERIES OF WEAK UPPER LEVEL
DISTURBANCES MOVE THROUGH THE REGION. A FEW OF THESE STORMS WILL
HAVE THE POTENTIAL TO BECOME SEVERE EACH DAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EVENING ALONG
AND WEST OF A WAUNETA COLORADO TO GOODLAND TO TRIBUNE KANSAS LINE.

LAMMERS