Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 310953
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
353 AM MDT SUN MAY 31 2015

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 310 AM MDT SUN MAY 31 2015

NARROW LINE OF LIGHT SHOWERS PROGRESSING OVER SE WYOMING INTO THE
NORTHERN PANHANDLE EARLY THIS MORNING AS A MINOR SHORTWAVE MOVES
ACROSS THE AREA. EXPECT THIS TO MOVE OUT OF THE CWA WITHIN A FEW
HOURS WITH SOME CLEARING BEHIND THIS WAVE.

UPPER RIDGING WILL AMPLIFY SOME OVER THE REGION TODAY AND TONIGHT
WITH WARMING MID LEVEL TEMPS. TEMPS SHOULD WARM WELL INTO THE 70S
ACROSS THE PLAINS OF THE CWA TODAY WITH SOME LOWER 80S OVER THE
PANHANDLE AS WELL. NEXT IMPULSE WILL MOVE ACROSS THE REGION THIS
AFTERNOON AND SHOULD INTERACT WITH CAPES FROM ABOUT 500-1000 J/KG
MAINLY OVER THE PLAINS TO SET OFF SCTD SHOWERS AND TSTMS. A FEW
STRONGER STORMS POSSIBLE WITH HAIL THE MAIN THREAT. ACTIVITY WILL
DIMINISH DURING THE EVENING AS THE SHORTWAVE DROPS SOUTHEAST OVER
THE CENTRAL PLAINS. ON MONDAY THE UPPER RIDGE AXIS SHOULD EDGE
EAST ACROSS THE CWA WHILE THE NEXT SHORTWAVE MOVES THROUGH IT AND
OVER THE HIGH PLAINS BY MONDAY EVENING. SHOULD SEE ANOTHER ROUND
OF SCTD SHOWERS AND TSTMS DEVELOP IN THE AFTERNOON ACROSS THE MTNS
INTO THE PLAINS. SOMEWHAT BETTER MOISTURE WILL CONTRIBUTE TO
HIGHER CAPE VALUES ESPECIALLY OVER THE PANHANDLE WHERE VALUES IN
EXCESS OF 2500 J/KG PROGGED. SHEAR WILL BE SOMEWHAT LACKING
HOWEVER BUT SOME STRONG STORMS LIKELY. AGAIN THIS ACTIVITY SHOULD
WANE DURING THE EVENING. LESS CONVECTIVE ACTIVITY EXPECTED FOR
TUESDAY AS A SFC TROF MOVES INTO THE PLAINS BUT THIS TROF SHOULD
SERVE TO FOCUS CONVECTION TUESDAY AFTERNOON OVER THE PANHANDLE
WITH PRETTY GOOD CAPES PROGGED JUST EAST OF THE CWA.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 310 AM MDT SUN MAY 31 2015

GFS/ECM/GEM ARE ALL IN GOOD AGREEMENT WITH DEEP TROUGHING OVER THE
WESTERN CONUS THROUGH THE EXTENDED PERIOD. THIS WILL RESULT IN MOIST
SOUTHWEST FLOW ALOFT OVER THE CWA THROUGH MID TO LATE WEEK....LIKELY
YIELDING AN ACTIVE PATTERN FOR CONVECTION. PERSISTENT EAST-SOUTHEAST
LLVL UPSLOPE WILL HELP TO MAINTAIN DEW POINTS IN THE 50S TO THE EAST
OF THE LARAMIE RANGE. BOTH THE GFS AND ECMWF SHOW SFC CAPE VALUES OF
1500-3000 J/KG EACH AFTN FROM WED ONWARD...ALONG WITH 0-6 KILOMETER
SHEAR AVERAGING BETWEEN 30 AND 40 KTS. WHILE CONVECTIVE COVERAGE MAY
BE LIMITED BY PERIODS OF SHORTWAVE RIDGING...FAVORABLE DIVERGENCE AT
H25 AND LLVL CONVERGENCE WILL HELP PROMOTE AT LEAST ISOLATED/WIDELY
SCATTERED SHOWERS AND THUNDERSTORMS. CONFIDENCE IS FAIRLY HIGH THAT
SEVERE STORMS WILL OCCUR IN THIS PATTERN. DAYTIME HIGH TEMPERATURES
WILL REMAIN NEAR SEASONAL NORMS WITH PLENTIFUL CLOUDS EXPECTED EACH
AFTERNOON/EVE. THIS...COMBINED WITH COOL UPSLOPE...SUGGESTS HIGHS A
FEW DEGREES BELOW CURRENT MOS GUIDANCE.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1046 PM MDT SAT MAY 30 2015

LATEST RADAR IMAGERY SHOWING SOME SHOWERS AND THUNDERSTORMS NEAR
KRWL THAT SHOULD MOVE EAST AND OUT OF THE AERODROME BEFORE 06Z.
VFR CONDITIONS EXPECTED THROUGH AT LEAST SUNDAY AFTERNOON.
CONVECTION EXPECTED TO RETURN LATE AFTERNOON THAT COULD POSE SOME
ISSUES FOR AVIATION FLIGHT SAFETY. WILL FINE TUNE TIMING AND
LOCATIONS AS WE DRAW CLOSER TO THE EVENT.

&&

.FIRE WEATHER...
ISSUED AT 310 AM MDT SUN MAY 31 2015

WARMER TEMPERATURES CAN BE EXPECTED ACROSS THE DISTRICTS TODAY
WITH WARM TEMPERATURES EXPECTED TO HOLD THROUGH THE WEEK. THERE
WILL BE THE FAIRLY TYPICAL LATE DAY SCATTERED SHOWERS AND
THUNDERSTORMS MOST DAYS THIS WEEK AS WEAK IMPULSES INTERACT WITH
AFTERNOON AND EVENING INSTABILITY.

&&

.HYDROLOGY...
ISSUED AT 310 AM MDT SUN MAY 31 2015

THE LARAMIE AND NORTH PLATTE RIVERS OVER THE PLAINS ARE FORECAST
TO BE STEADY OR SLOWLY FALL OVER THE NEXT COUPLE DAYS AS EXCESS
WATER FROM RAINFALL MOVES ON DOWNSTREAM. FOR THE UPPER LARAMIE
RIVER AND THE UPPER NORTH PLATTE RIVER WARMING TEMPS WILL INCREASE
SNOWMELT WHICH WILL IN TURN BRING THESE RIVER SECTIONS TOWARDS OR
EVEN EXCEEDING BANKFULL EARLY IN THE WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...CLH
AVIATION...GCC
FIRE WEATHER...RE
HYDROLOGY...RE


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