Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 192351
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
551 PM MDT FRI SEP 19 2014

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 350 PM MDT FRI SEP 19 2014

NEAR TERM FORECAST CONCERNS REVOLVE AROUND PCPN CHANCES FOR THE REST
OF THE AFTN AND EVE. WATER VAPOR SATELLITE SHOWS A WELL PRONOUNCED
UPPER-LEVEL SHORTWAVE MOVING ACROSS NORTHWEST WY AT 20Z. ASSOCIATED
SFC COLD FRONT HAS MADE LITTLE FORWARD PROGRESS THIS AFTN...ANALYZED
FROM SOUTHWEST TO NORTHEAST ACROSS THE STATE. THIS FEATURE COMBINED
WITH MODEST LARGER SCALE SUPPORT SHOULD SERVE AS A FOCUS FOR SHOWER
AND TSTM DEVELOPMENT IN THE NEXT FEW HOURS. HRRR HAS BEEN CONSISTENT
WITH SHOWING ISOLATED ACTIVITY FROM SOUTHEAST WY INTO THE SOUTHERN
NE PANHANDLE BETWEEN 22Z AND 02Z. LACK OF SUBSTANTIAL FORCING SHOULD
KEEP THINGS ISOLATED. GFS AND NAM BUFKIT SOUNDINGS INDICATE INVERTED
V LLVL PROFILES OVER MUCH OF THE CWA. DCAPES AROUND 1300 J/KG ON THE
LATEST SPC MESOANALYSIS SUGGESTS GUSTY OUTFLOW WINDS COULD BE A BIT
OF A PROBLEM TONIGHT. DID NOT MENTION IN THE GRIDS WITH COVERAGE NOT
HIGH ENOUGH TO WARRANT.

COLD FRONT IS PROGGED TO SWEEP ACROSS THE CWA BY LATE TONIGHT. DRIER
AIR WILL SLOWLY WORK INTO THE AREA...ENDING CHANCES FOR PCPN FROM NW
TO SE BY 06Z SAT. GFS AND NAM SHOW H7 TEMPS COOLING TO 6 TO 8 DEG C
OVER THE PLAINS BY SAT AFTN...DOWN FROM AROUND TODAYS 13 C OVER CYS
PER A RECENT LAPS SOUNDING ANALYSIS. DRY COLUMN OVERHEAD FOR SAT AS
HIGH-AMPLITUDE UPPER RIDGING TAKES OVER...SO LOOKING AT MOSTLY SUNNY
SKIES AND A SUBSTANTIAL COOLDOWN FROM TODAYS HIGHS. NEXT CONCERN IS
A LARGE CUTOFF LOW CURRENTLY SEEN ON WATER VAPOR SATELLITE OVER WEST
CENTRAL CALIFORNIA. THIS FEATURE WILL LIFT SLOWLY NORTHEAST ON SUN
WITH INCREASING 700-300 MILLIBAR MOISTURE OVER CARBON COUNTY BY 12Z.
MOISTURE AND QG ASCENT OVERSPREADS THE CWA THROUGH THE REMAINDER OF
THE FCST PERIOD. LLVL UPSLOPE AND SOME CLOUD COVER SUGGESTS SUN AFTN
SHOULD BE QUITE COOL. THE MAJORITY OF MOS GUIDANCE SUGGESTS HIGHS AT
70F OR BELOW AS A GENERAL RULE...SO TRENDED LOWER ON TEMPS. ISOLATED
TO SCATTERED SHOWER AND THUNDERSTORM ACTIVITY WILL INCREASE FROM SW
TO NE DURING THAT TIME FRAME.

.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 350 PM MDT FRI SEP 19 2014

MODELS ARE IN GOOD AGREEMENT AT SHOWING THE UPPER LOW OVER THE
GREAT BASIN MOVING EASTWARD ON MON AND LOCATED OVER NORTHERN WY BY
THE AFTN. GOOD UPPER LEVEL DIFFLUENCE WILL DEVELOP DURING THE
DAY...ESPECIALLY ACROSS THE PLAINS. SCATTERED SHOWERS AND TSTMS
WILL BE POSSIBLE THROUGH THE DAY. LOOKING AT SOUNDINGS AND
CONVECTIVE PARAMETERS OVER THE NEBRASKA PANHANDLE...COULD SEE A
FEW STRONGER STORMS WITH SMALL HAIL. MIDLVL LOW CONTINUES EASTWARD
INTO SOUTH DAKOTA ON MON NIGHT AND TUES WITH LARGE SCALE
SUBSIDENCE FOLLOWING. PRECIP CHANCES COME DOWN ON TUES AS THE BEST LIFT
AND MOISTURE IS WELL EAST...HOWEVER KEPT SLIGHT CHANCE POPS DURING
TH AFTN WITH WEAK INSTABILITY COMBINED WITH MODEST MIDLVL
MOISTURE ON THE BACKSIDE OF THE LOW. IT WILL BE BREEZY ON TUES
WITH ENHANCED NORTHWEST FLOW ALOFT AND GOOD MIXING. THE REMAINDER
OF THE LONG TERM WILL FEATURE INCREASING HEIGHTS AS A RIDGE BUILDS
OVER THE INTERMOUNTAIN WEST IN ADVANCE OF A LARGE SCALE TROUGH OFF
THE WEST COAST. TEMPS WILL BE SLIGHTLY ABOVE SEASONAL NORMS AND
WINDS WILL BE RELATIVELY WEAK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY AFTERNOON)
ISSUED AT 551 PM MDT FRI SEP 19 2014

ISOLATED SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH AROUND
02Z FROM VCTS KCYS TO KSNY. GUSTY WEST TO NORTHWEST WINDS WILL
EASE THROUGH SUNSET WITH WINDS REMAINING LIGHT THROUGH SATURDAY
AFTERNOON. WINDS WILL SHIFT TO THE NORTH TO NORTHEAST LATE
SATURDAY AFTERNOON...WITH GUSTS TO 20 KTS POSSIBLE ACROSS THE
WYOMING PLAINS AND NORTHERN NEBRASKA PANHANDLE.

&&

.FIRE WEATHER...
ISSUED AT 350 PM MDT FRI SEP 19 2014

A WEAK COLD FRONT WILL MOVE ACROSS SOUTHEAST WY AND THE WESTERN NE
PANHANDLE TONIGHT. ISOLATED TO WIDELY SCATTERED SHOWERS AND STORMS
WILL BE POSSIBLE THROUGH THE AFTN AND EVE WITH GUSTY OUTFLOW WINDS
THE PRIMARY HAZARD. COOLER AND DRIER FOR SAT IN THE POST-FRONTAL AIR
MASS WITH LITTLE OR NO CHANCE FOR PCPN. THE NEXT CHANCE FOR WETTING
RAINS WILL BE FROM SUN NIGHT THROUGH TUE AS A POTENT WEATHER SYSTEM
MOVES SLOWLY NORTHEAST ACROSS THE REGION. CRITICAL FIRE WEATHER IS
NOT EXPECTED IN THE FORESEEABLE FUTURE.

&&

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

$$

SHORT TERM...HAMMER
LONG TERM...FINCH
AVIATION...RJM
FIRE WEATHER...HAMMER






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