Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 211710
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1110 AM MDT TUE APR 21 2015

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 315 AM MDT TUE APR 21 2015

QUIET WEATHER THIS MORNING WITH SOME MID CLOUDS OVER SE WY KEEPING
TEMPS UP A BIT AND HINDERING ANY FOG FORMATION. NWLY FLOW ALOFT
WILL REMAIN OVER THE CWA THROUGH WEDS THEN TURN WESTERLY WEDS
NIGHT AND THURSDAY. A WEAK FRONT WILL SETTLE DOWN THE PLAINS LATER
THIS AFTERNOON INTO THIS EVENING AND LAY UP AGAINST THE MTNS BUT
NO SIGNIFICANT EFFECT SEEN FROM THIS THROUGH TONIGHT. SOME WEAK
INSTABILITY OVER WESTERN PARTS OF THE CWA SHOULD ALLOW FOR A FEW
SHOWERS TO DEVELOP THIS AFTERNOON WITH A TSTORM OR TWO NOT OUT OF
THE QUESTION. ACTIVITY WILL DECREASE THIS EVENING. AN APPROACHING
SHORTWAVE ON WEDS SHOULD ALLOW FOR SOMEWHAT BETTER COVERAGE OF
SHOWERS AND A FEW TSTORMS WEDS...MAINLY OVER SE WY WHERE SOME
MINOR UPSLOPE COMPONENT TO THE WIND SHOULD EXIST. SIMILAR PATTERN
FOR THURSDAY BUT PCPN SHOULD PROGRESS FARTHER EASTWARD OVER THE
PLAINS AND THE PANHANDLE AS THE SFC FRONT SLIPS BACK EAST.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 345 AM MDT TUE APR 21 2015

MINOR DIFFERENCES ARE APPARENT WITH THE 00Z/06Z DETERMINISTIC
MODEL GUIDANCE. FAIRLY BROAD UPPER TROUGH OVER THE INTERMOUNTAIN
WEST WILL PROGRESS EASTWARD WITH WEAK UPPER LOW MOVING SLOWLY
FROM THE FOUR CORNERS TO SOUTHEAST CO THURSDAY NIGHT AND CENTRAL
GREAT PLAINS BY FRIDAY EVENING. A SURFACE TROUGH BISECTING A PAIR
OF LOWS WILL LIE EAST OF THE LARAMIE RANGE. A RATHER MOIST
SOUTHEASTERLY UPSLOPE FLOW WITH DEW POINTS IN THE 40S COMBINED
WITH MODEST INSTABILITY /LIS -3 TO -5C/ AND WEAK UPPER LEVEL
DISTURBANCE WILL PRODUCE A DECENT COVERAGE OF SHOWERS AND
ISOLATED TSTORMS THURSDAY NIGHT AND FRIDAY. SHOWER COVERAGE
DECREASES SLIGHTLY FRIDAY NIGHT WITH THE EXIT OF THE DISTURBANCE.
SHORTWAVE TRANSITORY RIDGE ALOFT EARLY SATURDAY SLIDES EAST INTO
THE PLAINS SATURDAY AFTERNOON WHEN A STRONGER DISTURBANCE MOVES
ACROSS WY AND CO PRODUCING SCATTERED SHOWERS AND POSSIBLY A FEW
TSTORMS. THE GFS IS MORE PROGRESSIVE WITH THIS TROUGH AND CLEARS
OUT THE SHOWERS SATURDAY NIGHT WHILE THE ECMWF IS SLOWER AND KEEPS
THE CWA SHOWERY THROUGH SUNDAY. AREAS ALONG AND SOUTH OF I-80 IN
SOUTHEAST WY MAY SEE ISOLATED SHOWERS SUNDAY AFTERNOON WITH WEAK
OROGRAPHIC FLOW. A DRIER STABLE AIR MASS WILL PREVAIL MONDAY WITH
LARGE SCALE RIDGE OVER THE ROCKY MOUNTAINS. TRENDED TOWARD THE
COOLER ECMWF BIAS FOR TEMPERATURES WHICH WILL AVERAGE NEAR TO
SLIGHTLY ABOVE SEASONAL NORMALS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1109 AM MDT TUE APR 21 2015

VFR CONDITIONS EXPECTED WITH AFTERNOON SHOWERS POSSIBLE AT KLAR
AND KRWL. NO IMPACTS TO AVIATION EXPECTED.

&&

.FIRE WEATHER...
ISSUED AT 315 AM MDT TUE APR 21 2015

CONCERNS EXPECTED TO REMAIN LOW FOR THE NEXT SEVERAL DAYS WITH
WEATHER CONDITIONS REMAINING NON-CRITICAL OVERALL. A FEW
THUNDERSTORMS WILL BE POSSIBLE MAINLY IN THE AFTERNOONS FOR THE
NEXT FEW DAYS BUT DRY LIGHTNING IS NOT EXPECTED. TEMPERATURES
WILL BE MILD THROUGH THE WEEK.

&&

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

$$

SHORT TERM...RE
LONG TERM...MJ
AVIATION...GCC
FIRE WEATHER...RE



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