Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 221755
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1155 AM MDT MON SEP 22 2014

.UPDATE...
ISSUED AT 1113 AM MDT MON SEP 22 2014

TWO DISTINCT AREAS OF RAIN ARE CURRENTLY MOVING OVER THE CWA. ONE
IS ACROSS THE NEBRASKA PANHANDLE WITH GENERALLY LIGHT RAIN
OBSERVED AND NO LIGHTNING. THE OTHER IS TO THE WEST OF THE LARAMIE
RANGE CLOSER TO THE MIDLVL LOW CENTER AND THERE IS ISOLATED
EMBEDDED TSTMS. THE QUESTION THIS AFTN IS HOW MUCH CLEARING AND
INSTABILITY WILL BE PRESENT OVER THE PLAINS. BOTH THE GFS AND NAM
SHOW LI VALUES OF AROUND -3C TO -4C ALONG THE WY-NE BORDER AND
EASTWARD INTO THE PANHANDLE AT 00Z. COMBINED WITH MODEST DEEP
LAYER SHEAR (AROUND 30 KTS) COULD SEE SOME STRONGER STORMS WITH
SMALL HAIL. THE HRRR ALSO INDICATES A FEW HIGHER REFLECTIVITY
CORES DEVELOPING IN THE SOUTHERN PANHANDLE AFTER 23Z. THUS...ADDED
THE MENTION OF SMALL HAIL INTO THE GRIDS FOR MUCH OF THE PANHANDLE
AND FAR EASTERN LARAMIE COUNTY DURING THE AFTN AND EARLY EVENING.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 322 AM MDT MON SEP 22 2014

A FEW SHOWERS MOVING NORTHEAST ACROSS NORTHERN COLORADO BUT HAVING
SOME TROUBLE SURVIVING OFF THE MOUNTAINS SO FAR. MEANWHILE AN
UPPER LOW CURRENTLY AROUND THE UTAH/IDAHO BORDER WILL MOVE
NORTHWARD THIS MORNING THEN TURN MORE EASTWARD THROUGH THIS
EVENING EMERGING OVER THE NORTHERN HIGH PLAINS TONIGHT. AN IMPULSE
ROTATING AROUND THE UPPER LOW WILL SWING ACROSS THE CWA THIS
AFTERNOON AND EVENING WITH SCTD SHOWERS AND TSTRMS ASSOCIATED WITH
IT. INSTABILITY WILL BE RATHER WEAK ACROSS MUCH OF THE CWA THIS
AFTERNOON BUT A TONGUE OF BETTER INSTABILITY/CAPES 500-100 J/KG/
LOOKS TO NOSE UP OUT OF COLORADO INTO MAINLY THE SOUTHERN
PANHANDLE INTO THIS EVENING WHICH WITH MARGINAL SHEAR MAY ALLOW
FOR A FEW STRONGER STORMS THERE. ACTIVITY WILL MOVE OUT OF THE CWA
TONIGHT AS THE UPPER IMPULSE SWINGS EAST OF THE AREA AND A WEAK
PACIFIC FRONT MOVES OUT ACROSS THE HIGH PLAINS. MAINLY DRY AND
WARM TUESDAY THOUGH ANOTHER MODEST SHORTWAVE CLIPPING NORTHEAST
PARTS OF THE CWA MAY SET OFF A FEW SHOWERS/TSTMS OVER THAT AREA
TUESDAY AFTERNOON. DRY AND WARMER WEDS AS AN UPPER RIDGE AMPLIFIES
AND BUILDS NORTHEAST ACROSS THE NORTHERN AND CENTRAL ROCKIES.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 322 AM MDT MON SEP 22 2014

SHARP UPPER LEVEL RIDGING BUILDS INTO THE AREA WEDNESDAY NIGHT
INTO THURSDAY. 700MB TEMPERATURES RESPOND AS WELL...CLIMBING TO
+14C AND EVEN +16C ACROSS PORTIONS OF SOUTHERN CARBON AND ALBANY
COUNTIES THURSDAY AFTERNOON. THIS IS UP FROM +10C TO +12C
WEDNESDAY AFTERNOON. AS A RESULT...TEMPERATURES SHOULD BE WARMER
AND ALMOST SUMMER LIKE WITH 90S IN THE PANHANDLE AND MID 80S OUT
WEST. GOING TO BE DRY THROUGH AT LEAST FRIDAY AS WELL WITH SUNNY
SKIES AND LIGHT WINDS.

WEATHER BEGINS TO CHANGE SOME FRIDAY NIGHT INTO SATURDAY. MODELS
INITIALLY IN GOOD AGREEMENT WITH A PACIFIC LOW PRESSURE SYSTEM
MOVING INTO NEVADA OVERNIGHT FRIDAY. GFS MUCH FASTER...BY ROUGHLY
12 TO 18 HOURS ON THE EASTWARD MOVEMENT OF THIS LOW. NEW ECMWF
SLOWER AND HAS THE LOW NOT MOVING INTO NEVADA UNTIL SATURDAY
NIGHT/SUNDAY MORNING. GFS SOLUTION WOULD HAVE FAIRLY WIDESPREAD
SHOWER ACTIVITY FOR AREAS ALONG AND WEST OF THE LARAMIE RANGE
SATURDAY NIGHT INTO SUNDAY. ECMWF SOLUTION HAS SHOWERS MOVING INTO
CARBON COUNTY SUNDAY NIGHT INTO MONDAY. DID A BLEND OF THE TWO
MODELS FOR POPS OVER THE WEEKEND WITH LOW CHANCE POPS SATURDAY
NIGHT. BEST CHANCES LOOK TO BE THROUGH THE DAY SUNDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY MORNING)
ISSUED AT 1145 AM MDT MON SEP 22 2014

AVIATION CONCERNS ARE FOCUSED IN THE FIRST 6-12 HOURS OF THE
TERMINAL AS AN AREA OF LOW PRESSURE PUSHES THROUGH. 17-18Z RADAR
RETURNS SHOW FIRST BAND OF RAIN SHOWERS LIFTING ACROSS THE WRN
NEBRASKA PANHANDLE SITES...WITH THE 2ND PRECIP BAND APPROACH KLAR.
PREDOMINATED THE INITIAL BAND OF PRECIP AT KAIA AND KCDR. THE 2ND
BAND OF PRECIP WILL INCREASE IN COVERAGE AND INTENSITY THE AIR
MASS DESTABILIZES THIS AFTERNOON. AS SUCH...WAS CONFIDENT ENOUGH
TO ADD A TEMPO GROUP TO KLAR...WITH VCTS ELSEWHERE. WILL
UNDOUBTEDLY NEED TO ADD SOME TEMPO GROUPS TO OTHER SITES EAST OF
THE PLAINS THIS AFTERNOON...HOWEVER LESS CONFIDENT ON TIMING AND
PLACEMENT AT THIS TIME. LOW PRESSURE AREA PUSHES EAST OF THE AREA
EARLY TUESDAY...WITH CONDITIONS IMPROVING WEST TO EAST. OUTSIDE OF
THE TEMPO -TSRA GROUP AT KLAR...HAVE KEPT AREA TERMINALS VFR AT
THIS POINT...WITH THE EXPECTATION THAT THESE SOME AREAS WILL SEE
MVFR VSBYS IN HEAVIER SHOWERS/STORMS THIS AFTERNOON.

&&

.FIRE WEATHER...
ISSUED AT 322 AM MDT MON SEP 22 2014

NO SIGNIFICANT CONCERNS EXPECTED THROUGH AT LEAST MIDWEEK WITH MIN
RELATIVE HUMIDITIES EXPECTED TO REMAIN ABOVE CRITICAL LEVELS FOR
THE MOST PART. GUSTY WINDS EXPECTED THIS AFTERNOON OVER WESTERN
AREAS THEN LESS WIND ANTICIPATED TUESDAY AND WEDS. SCTD SHOWERS
AND TSTRMS TODAY WITH ACTIVITY MOVING EAST AND OUT OF THE AREA
THIS EVENING.

&&

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

$$

UPDATE...FINCH
SHORT TERM...RE
LONG TERM...CLAYCOMB
AVIATION...HAHN
FIRE WEATHER...RE







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