Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 230046
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
646 PM MDT TUE JUL 22 2014

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 306 PM MDT TUE JUL 22 2014

FAR LESS COVERAGE OF CU COMPARED TO THE SAME TIME MONDAY WHICH
SURELY IS INDICATIVE OF THE WARMER TEMPS ALOFT. SFC MOISTURE HAS
INCREASED BEHIND LAST NIGHTS WEAK BOUNDARY...WITH THE 50F
ISODROSOTHERM BANKED UP TO THE FRONT RANGE. AM BEGINNING TO SEE SOME
WEAK CONVECTIVE DEVELOPMENT MAINLY IN THE VICINITY OF THE NRN
LARAMIE RANGE...AND SOME NR THE SNOWY AND SOUTHERN LARAMIE RANGE
TOO. MESOANALYSIS SHOWS A PRETTY HEALTHY CAPPING INVERSION REMAINS
IN PLACE...ESPECIALLY OVR THE ERN PLAINS. EXPECT THIS CAP CONTINUE
TO ERODE THRU THE AFTERNOON. THE STRONGER CAP WILL MEAN DEEP
CONVECTION WILL BE A BIT LATER IN DEVELOPING...WHICH ACCORDING TO
THE HRRR WILL BE BETWEEN 3-6 PM. LARAMIE COUNTY AND THE SOUTHERN END
OF GOSHEN/PLATTE COUNTIES LOOK TO SEE THE BEST CHANCE INITIALLY.
WILL SEE ADDL DEVELOPMENT OVR NORTHEAST WYOMING DIVE SOUTHEAST INTO
FAR EAST CENTRAL WYOMING AND THE NRN NEBRASKA PANHANDLE THIS
EVENING. IT IS THIS AREA WHERE SEVERE POTENTIAL WILL BE GREATEST
WITH SBCAPES OF AROUND 2000 J/KG ONCE THE CAP BREAKS. THIS
CONVECTION WILL DISSIPATE BY AROUND SUNSET.

ATTENTION THEN TURNS TO A BETTER CHANCE FOR SEVERE THUNDERSTORM
DEVELOPMENT WEDNESDAY AFTERNOON. THERMODYNAMIC PROFILES WILL BE MORE
CONDUCIVE FOR THUNDERSTORM DEVELOPMENT WEDNESDAY AS MID-LEVEL
HEIGHTS/TEMPS FALL WITH THE APPROACH OF SHORTWAVE ENERGY. THIS WILL
MEAN LESS OF A CAP AND A LIKELY EARLIER START TO CONVECTIVE
INITIATION...WHICH SHOULD OCCUR OVR THE SNOWY/SIERRA MADRE RANGES BY
MIDDAY. PROGD SBCAPES OVR THE ERN PLAINS CLIMB ABOVE 3000 J/KG
WEDNESDAY AFTERNOON AND WHEN COMBINED WITH DEEP LAYER SHEAR OF 25-30
KNOTS SHOULD BE SUFFICIENT FOR SOME CONVECTIVE ACTIVITY BECOMING
SEVERE. STORMS WILL SPREAD ONTO THE SOUTHEAST WYOMING PLAINS
WEDNESDAY AFTERNOON AND INTO THE WESTERN NEBRASKA PANHANDLE DURING
THE EVENING. AREAS OVR THE SOUTHERN PANHANDLE MAY BE INFLUENCED A
BIT TOO MUCH BY THE CAP...WHICH MAY LIMIT CONVECTIVE STRENGTH THERE.
CONVECTION AGAIN WILL WANE WITH LOSS OF INSOLATION.

FIRST SHORTWAVE PUSHES THRU THURSDAY MORNING WITH A TRAILING
SHORTWAVE POISED TO MOVE THRU THURSDAY AFTERNOON. INSTABILITY AXIS
WILL BE FLATTENED AND WEAKENED BY THE INITIAL SHORTWAVE. SO EXPECT A
LESS FAVORABLE ENVIRONMENT FOR SEVERE THUNDERSTORM POTENTIAL. EVEN
SO...WEAK INSTABILITY PARAMETERS WILL BE SUFFICIENT FOR AT LEAST
SOME ISOLATED CONVECTIVE POTENTIAL. THURSDAY WILL BE THE WARMEST DAY
OF THE PERIOD WITH HIGH TEMPERATURES THAT WILL AGAIN REACH 90S AT
MOST LOCATION AND LOW TRIPLE DIGITS OVER LOWER ELEVATIONS OF THE
WESTERN NEBRASKA PANHANDLE.

.LONG TERM...(FRIDAY THROUGH MONDAY)
ISSUED AT 306 PM MDT TUE JUL 22 2014

HIGH PRESSURE CONTINUES TO REMAIN DOMINANT OVER THE FOUR CORNERS
REGION BUT BEGINS TO ERODE TO THE SOUTH OVER THE WKND. FAIRLY POTENT
TROUGH OF LOW PRESSURE MOVES ACROSS THE SOUTHERN CANADIAN PROVINCES
AND BRINGS A SERIES OF ASSOCIATED COOL FRONTS ACROSS THE AREA (THE
STRONGEST FRONT WILL BE SAT EVENING). UPSLOPE FLOW LOOKS TO DEVELOP
BY FRI AFTN AS DEW POINTS APPROACH THE MID 50S OVER THE PANHANDLE.
COULD SEE SOME ISOLATED SHOWERS AND THUNDERSTORMS DURING THIS
TIMEFRAME BOTH FRI AND SAT SO HAVE KEPT SOME SLIGHT POPS IN THE
FCST. THE ECMWF IS MORE MOIST THAN THE GFS ATTM AND GENERATES A
BETTER COVERAGE OF STORMS EACH AFTN AND EVENING. TEMPS BEGIN TO COOL
TO MORE SEASONABLE LEVELS IN THE LOW TO MID 80S FOR SUNDAY...BUT THE
RIDGE BEGINS TO BUILD BACK INTO THE AREA AND TEMPS SHOULD WARM TO
THE MID 80S BY MONDAY FOR SOUTHEASTERN WY AND NEAR 90 FOR AREAS OF
THE PANHANDLE AS 700 MB TEMPS WARM TO NEAR 15C.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY AFTERNOON)
ISSUED AT 641 PM MDT TUE JUL 22 2014

VFR CONDITIONS WILL BE A GENERAL RULE. HOWEVER...ISOLATED SHOWERS
AND THUNDERSTORMS ARE POSSIBLE THROUGH 06Z WED. GUSTY AND ERRATIC
WINDS AND HAIL ALOFT ARE THE MAIN AVIATION HAZARDS. IT IS POSSIBLE
THAT THESE STORMS COULD BECOME SEVERE WITH LARGE HAIL AS WELL AS
DAMAGING WINDS. BRIEF MVFR CONDITIONS ARE POSSIBLE BENEATH ANY
THUNDERSTORMS AS WELL. INCREASING CLOUDS IN THE MID LEVELS ON
WEDNESDAY AFTERNOON WITH ANOTHER GOOD POSSIBILITY OF SHOWERS AND
THUNDERSTORMS AFFECTING THE HIGH PLAINS.

&&

.FIRE WEATHER...
ISSUED AT 306 PM MDT TUE JUL 22 2014

WINDS HAVE HELD BELOW CRITICAL THRESHOLDS THUS FAR TODAY...DESPITE
RELATIVE HUMIDITIES THAT HAVE DROPPED BELOW 15 PERCENT. SOME
ISOLATED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER
LARAMIE COUNTY LATE THIS AFTERNOON AND OVER EXTREME EAST CENTRAL
WYOMING AND THE NORTHERN NEBRASKA PANHANDLE THIS EVENING. WEDNESDAY
WILL PROVIDE A BETTER OPPORTUNITY FOR AFTERNOON AND EVENING
THUNDERSTORMS ACROSS THE DISTRICT...SOME OF WHICH COULD POTENTIALLY
BECOME SEVERE IN LOCATIONS EAST OF THE LARAMIE RANGE. DRIER AND
BREEZIER CONDITIONS WILL EXIST OVER WESTERN CARBON AND CONVERSE
COUNTIES ON WEDNESDAY. CONDITIONS WILL LIKELY BECOME NEAR CRITICAL
IN THESE AREAS WEDNESDAY. THURSDAY LOOKS POTENTIALLY MORE CRITICAL
OVER WESTERN CARBON AND CONVERSE COUNTIES AND WILL LIKELY NEED TO
ISSUE A HEADLINE IN TIME. AFTERNOON AND EVENING SHOWER AND
THUNDERSTORM CHANCES WILL CONTINUE THURSDAY AND FRIDAY MAINLY FOR
AREAS EAST OF THE LARAMIE RANGE.

&&

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

$$

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






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