Severe Thunderstorm Warning 31, NWS Cheyenne, WY

ZCZC CYSWRKAFD ALL
TTAA00 KCYS 181738

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
145 PM MDT FRI MAY 30 2003

SHORT TERM...SEVERAL CONCERNS IN THE SHORT TERM.  88D NOT SHOWING
MUCH AS OF THIS WRITING BUT GUIDANCE SHOWING HIGHER POPS THAN GOING
FORECAST SO MAY NEED TO BUMP THEM UP ESPECIALLY IN THE SOUTHERN
PORTIONS OF THE CWA.  LIS AND CAPES WOULD SUGGEST TSRA
DEVELOPMENT  THIS AFTERNOON AND EVENING. SECONDLY WITH THE
POSSIBILITY OF LOCALLY HEAVY RAIN AND RAPID SNOW MELT...MBRFC IS
CONCERNED WITH LARAMIE RIVER POSSIBLY EXCEEDING FLOOD STAGE.

TRANSITORY 500H RIDGE TO CROSS CWA TONIGHT WITH PVA MOVING IN
BEHIND IT BY LATE TONIGHT AND EARLY MORNING HOURS.  THIS FEATURE
WILL BE THE TRIGGER FOR INCREASING THE POPS IN THE SOUTH.  GUIDANCE
ACTUALLY SHOWING HIGHER POPS AFTER MIDNIGHT THAN WITH THIS EVENINGS
CONVECTIVE ACTIVITY.  BY SATURDAY EVENING CWA BACK UNDER NW FLOW.
THE SFC PATTERN SHOWS HIGH PRESSURE TO THE E/NE WHICH WILL PROVIDE
SE/S FLOW NEXT 36 HOURS. THIS WILL INCREASE THE LOW LEVEL RH
RAPIDLY BY SATURDAY MORNING.  SOME AREAS EAST OF THE MOUNTAINS WILL
SEE LOW CLOUDS AND THIS AGAIN WILL PROVIDE ENOUGH LOW LEVEL MOISTURE
AND ALONG WITH THE FORECAST LIS/CAPE FOR MORE CONVECTION TOMORROW.

LONG TERM...UPPER FLOW DEVELOPS WESTERLY COMPONENT FROM SAT-SUN AS
STRONGER VORTICITY LOBES MOVE THROUGH. FLOW WILL HAVE SURFACE FEATURE
NEAR CONTINENTAL DIVIDE TO INTERACT WITH. BOTH ETA/AVN HAVE 0.1 TO
0.25 QPF AMOUNTS AT TIMES DURING PERIOD. UPPER FLOW RETURNS TO
NORTHWESTERLY FOR START OF WORKWEEK AND BECOMES NORTHERLY FOR LATER
PART OF WEEK WITH RESULTING SIGNIFICANT COOLING ALOFT/THICKNESSES.
BY MIDWEEK DRY BUT THREAT FROST POSSIBLE...ESPECIALLY LARAMIE/RAWLINS.

.CYS...
WY...NONE.
NE...NONE.

GRIFFITH/COX

NEZ001>003-019>021-054-055-WYZ059>070-311130-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHEYENNE WY
953 AM MDT FRI MAY 30 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEASTERN WYOMING AND THE
WESTERN NEBRASKA PANHANDLE.

.DAY ONE...TODAY AND TONIGHT

SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP IN THE AFTERNOON
WITH THE SHOWERS BECOMING MORE WIDESPREAD DURING THE EVENING.  DUE
TO COOLER AIR MOVING IN FROM THE NORTHEAST...THE BEST INSTABILITY
WILL BE SOUTH OF A DOUGLAS WYOMING TO SIDNEY NEBRASKA LINE.  THE
MAIN THREAT TODAY APPEARS TO BE DOWNBURST WINDS THAT COULD EXCEED 60
MPH AND CAUSE VERY LOCALIZED DAMAGE.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

ONLY A FEW THUNDERSTORMS ARE EXPECTED SATURDAY AFTERNOON AND EVENING
WITH THESE FORMING ALONG AND EAST OF INTERSTATE 25.  ONE OR TWO
COULD AGAIN PRODUCE SOME SMALL HAIL OVER THE PLAINS OF SOUTHEAST
WYOMING WITH AN ISOLATED SEVERE EVENT NOT OUT OF THE QUESTION.  ANOTHER
CHANCE OF THUNDERSTORMS WILL OCCUR BOTH SUNDAY AND MONDAY AFTERNOON
AND EVENING.  EVEN COOLER TEMPERATURES WILL MOVE IN TUESDAY ALONG
WITH A CHANCE OF SHOWERS AND A FEW THUNDERSTORMS.  DRY AND RATHER
COOL CONDITIONS ARE EXPECTED WEDNESDAY AND THURSDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED LATER THIS AFTERNOON AND EVENING.

GRIFFITH