Flash Flooding and Damaging Winds in Colorado, August 6 to 8, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GOODLAND KS
200 PM MDT WED AUG 6 2008

.SHORT TERM... (TONIGHT - SATURDAY)
200 PM MDT WED AUG 6 2008

FORECAST PROBLEM WILL BE PRECIPITATION EVENT TONIGHT AND INTO
THURSDAY. UPPER RIDGE ALOFT YIELDING NEARLY CALM 0-6KM MEAN WINDS
AND SLOW STORM MOTIONS. SURFACE ANALYSIS SHOWS LOW PRESSURE OVER
SOUTHEAST COLORADO AND HIGH PRESSURE BUILDING IN OVER
NEBRASKA...RESULTING IN MOIST SOUTHEASTERLY SURFACE WINDS.
PRECIPITABLE WATER VALUES ARE NEARLY 2 STANDARD DEVIATIONS ABOVE
NORMAL. THIS IS MORE OR LESS A CLASSIC SET UP FOR HEAVY RAIN ON THE
HIGH PLAINS. LIFT WILL BE PROVIDED BY SHORTWAVE COMING OUT OF
COLORADO...AS WELL AS MID LEVEL CONVERGENCE ASSOCIATED WITH
REINFORCING BACK DOOR FRONT COMING OUT OF CENTRAL NEBRASKA. THE
CONVERGENCE AXIS AT 310K SETS UP THIS EVENING FROM YUMA TO GOVE AND
REMAINS STATIONARY OR PERHAPS DRIFTS SOUTHWEST THROUGH THE NIGHT.
THIS SHOULD BE THE AXIS OF HEAVIEST RAINFALL THROUGH THE OVERNIGHT
HOURS.

RAIN WILL GRADUALLY END FROM NORTH TO SOUTH DURING THE DAY ON
THURSDAY. HEAVY RAIN WILL CONTINUE TO BE POSSIBLE AS THE SYNOPTIC
SITUATION CHANGES VERY LITTLE. TEMPERATURES SHOULD GO NOWHERE
PARTICULARLY IN THE SOUTHWEST HALF AND WENT WITH LOWEST GFS ENSEMBLE
MEMBER FOR HIGHS.

DURING THE REMAINDER OF THE SHORT TERM PERIOD...UPPER RIDGE WILL
AMPLIFY OVER THE GREAT BASIN WITH RIDGE AXIS FORECAST JUST WEST OF
THE ROCKIES. HOWEVER THERE ARE SOME WEAK EMBEDDED SHORTWAVE TROUGHS
FORECAST TO RIDE OVER THE RIDGE. MOISTURE WILL BEGIN TO BE A PROBLEM
AS IT IS GRADUALLY RESTRICTED TO AREAS CLOSER TO THE FRONT
RANGE...BUT APPEARS TO BE SOME RESIDUAL MOISTURE IN THE SOUTHWEST
ZONES ON FRIDAY TO WARRANT LOW POPS. STRONGER SHORTWAVE PROGGED FOR
SATURDAY...AND STORMS LIKELY TO INITIATE ON THE FRONT RANGE WITH
DAYTIME HEATING...MIGRATING EASTWARD SATURDAY NIGHT WITH THE AID OF
THE UPPER SHORTWAVE.

.LONG TERM... (SUNDAY - WEDNESDAY)
200 PM MDT WED AUG 6 2008

MAIN UPPER FEATURES WILL BE A LOW NEAR HUDSON BAY IN CANADA AND
RIDGE NEAR THE FOUR CORNERS...BOTH OF WHICH WILL BE NEARLY
STATIONARY THIS PERIOD. NORTHWEST FLOW WILL EXIST BETWEEN THEM
GENERALLY OVER THE NORTHERN PLAINS. NO DOUBT SEVERAL SHORTWAVE
TROUGHS WILL MOVE THROUGH THAT NORTHWEST FLOW...AND BRING A CHANCE
OF CONVECTION TO THE AREA. BETTER CHANCES CERTAINLY WILL BE TO THE
NORTH...BUT APPEARS WILL BE CLOSE ENOUGH TO THE NORTHWEST FLOW TO
GET A PIECE OF THE LIFT ASSOCIATED WITH THE SHORTWAVES. STILL TOO
EARLY TO RESOLVE TIMING AND PLACEMENT OF BEST LIFT...SO WILL CARRY
SOME SLIGHT TO LOW CHANCE POPS. TEMPERATURES SHOULD CONTINUE TO BE
NEAR OR SLIGHTLY BELOW NORMAL IN THIS PATTERN.

24
&&

.AVIATION...
1237 PM MDT WED AUG 6 2008

FOR THE 18Z TAF CYCLE...LOW CLOUDS LINGERING OVER KMCK HAVE KEPT IFR
CONDITIONS IN PLACE THERE FOR MOST OF THIS MORNING AND WELL INTO
THIS AFTERNOON. IF CONDITIONS IMPROVE FOR KMCK...IT WILL ONLY BE
BRIEF AS SHOWERS AND THUNDERSTORMS WILL RETURN TO KMCK BEGINNING TO
WORSEN CONDITIONS AGAIN AROUND 21Z AND LASTING THROUGH AROUND 06Z.
BUT KMCK MAY ALSO HAVE SOME FOG AND REPEATED IFR CONDITIONS FROM 10Z
TO 14Z. FINALLY...AFTER 15Z...VFR CONDITIONS SHOULD RETURN TO KMCK.
FOR KGLD...VFR CONDITIONS TO START WITH THIS AFTERNOON...THEN VCTS
MOVING IN AFTER 21Z. EXPECT THUNDERSTORMS AFTER 00Z AND A DROP INTO
MVFR CONDITIONS AFTER 06Z AND LASTING THROUGH THE REMAINDER OF THE
TAF PERIOD.

BLM
&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GOODLAND KS
1046 AM MDT WED AUG 6 2008

COZ090>092-KSZ001>004-013>016-027>029-041-042-NEZ079>081-071230-
YUMA-KIT CARSON-CHEYENNE CO-CHEYENNE KS-RAWLINS-DECATUR-NORTON-
SHERMAN-THOMAS-SHERIDAN-GRAHAM-WALLACE-LOGAN-GOVE-GREELEY-WICHITA-
DUNDY-HITCHCOCK-RED WILLOW-
1046 AM MDT WED AUG 6 2008 /1146 AM CDT WED AUG 6 2008/

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

SCATTERED TO NUMEROUS THUNDERSTORMS WILL DEVELOP OVER THE AREA
THIS AFTERNOON AND CONTINUE THROUGH TONIGHT...SOME OF WHICH COULD
EASILY BECOME SEVERE WITH THE MAIN THREATS BEING LARGE HAIL...DAMAGING
WINDS...CLOUD TO GROUND LIGHTNING AND VERY HEAVY RAINFALL.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

SCATTERED THUNDERSTORMS WILL CONTINUE INTO THURSDAY BEFORE
BECOMING MORE ISOLATED THAT NIGHT. A CHANCE OF THUNDERSTORMS WILL
CONTINUE OVER MOST OF THE AREA FROM FRIDAY INTO TUESDAY. AT THIS
TIME...NONE OF THESE STORMS ARE EXPECTED TO BECOME SEVERE WITH THE
MAIN THREATS BEING LOCALLY HEAVY RAINFALL AND CLOUD TO GROUND
LIGHTNING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED THIS AFTERNOON THROUGH TONIGHT
ACROSS THE ENTIRE REGION.

BULLER/BLM