Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 020514
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1114 PM MDT FRI AUG 1 2014

.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)

SHOWERS WITH A FEW EMBEDDED TSTORMS ARE DEVELOPING JUST NORTH AND
NORTHWEST OF THE CWA THIS AFTERNOON IN ADVANCE OF A WEAK SHORTWAVE
EVIDENT ON WATER VAPOR MOVING SOUTHEAST ACROSS WYOMING. STILL EXPECT
SOME OF THIS ACTIVITY TO TREK SOUTHWARD INTO THE CWA WHILE ALSO
DEVELOPING ALONG THE PINE RIDGE AND MOUNTAINS OF SOUTHEAST WYOMING.
THUS MAINTAINED A SLIGHT CHANCE FOR ISOLATED THUNDER IN THESE AREAS
THROUGH THE EARLY EVENING. EXTENDED THE RISK SLIGHTLY FURTHER SOUTH
FROM THE PREVIOUS FORECAST TO THE NORTH PLATTE RIVER VALLEY TO LINE
UP WITH DEVELOPING TOWERING CU SEEN ON VIS SAT IMAGERY...IN ADDITION
TO THE LATEST HRRR GUIDANCE. LATEST MESOANALYSIS SHOWS MINIMAL CAPE
IN PLACE ACROSS THE AREA THO...SO NOT EXPECTING THIS ACTIVITY TO
BECOME STRONG NOR WIDESPREAD THIS AFTERNOON.

THE UPPER RIDGE AXIS WILL SLOWLY SHIFT EASTWARD TOWARD THE ROCKIES
TONIGHT AND SATURDAY...WITH THE MID LEVELS LOOKING OVERALL LESS
ENERGETIC THAN TODAY. A WEAK FRONT LOOKS TO DROP SOUTH ACROSS THE
AREA ON SATURDAY...WITH PERHAPS A FEW SHOWERS AND WEAK STORMS
DEVELOPING OVER THE MOUNTAINS IN THE AFTERNOON AS WINDS WILL BECOME
MORE OF AN UPSLOPE COMPONENT BEHIND THE FRONT. WITH MINIMAL UPPER
SUPPORT ANTICIPATED...AM NOT VERY CONFIDENT COVERAGE WILL SHIFT INTO
THE PLAINS...SO CONFINED CHANCES FOR THUNDER TO THE MOUNTAINS.
CONDITIONS WILL REMAIN WARM WITH H7 TEMPS RANGING FROM 10 TO 14C.
SIMILAR CONDITIONS ARE EXPECTED FOR SUNDAY WITH TEMPS A FEW DEGREES
WARMER AS THE THERMAL RIDGE AXIS APPROACHES FROM THE WEST.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 300 PM MDT FRI AUG 1 2014

MODELS IN DECENT AGREEMENT WITH THE OVERALL PATTERN THROUGH NEXT
WEEK...SHOWING MONSOON MOISTURE INCREASING OVER THE FORECAST AREA
AS THE MID TO UPPER LEVEL FLOW BECOMES MORE SOUTHWESTERLY AHEAD OF
A WEAK SHORTWAVE ACROSS THE EASTERN PACIFIC. AS FOR INDIVIDUAL
DISTURBANCES/SHORTWAVE ENERGY MOVING NORTHWARD AND EVENTUALLY
EASTWARD ACROSS THE AREA...MODELS SHOW POOR CONSISTENCY AND ARE
OUT OF SYNC WITH THE MOVEMENT AND TIMING. THE ECMWF IS INITIALLY
18 TO 24 HOURS LATER THAN THE GFS AND GEM...WITH THE GEM ALSO
MUCH WEAKER WITH THE FIRST DISTURBANCE ON TUESDAY THAN THE OTHER
MODELS. THIS CONTINUES INTO LATE NEXT WEEK WITH THE MAIN SHORTWAVE
TROUGH AS IT MOVES NORTHEAST FROM SOUTHERN CALIFORNIA TO THE
CENTRAL ROCKY MOUNTAINS. THIS IS MAKING POP AND WEATHER FORECASTS
DIFFICULT GOING INTO NEXT WEEK IN TERMS OF WHICH DAYS HAVE THE
HIGHEST POTENTIAL FOR WIDESPREAD RAINFALL AND THUNDERSTORM
OUTBREAKS. THEREFORE...KEPT POP NO HIGHER THAN 40 PERCENT OUTSIDE
OF THE MOUNTAINS DUE TO LOWER THAN AVERAGE CONFIDENCE. DO EXPECT
SHOWERS AND TSTORMS NEARLY EVERYDAY HOWEVER. TUESDAY APPEARS TO BE
THE BEST DAY FOR WIDESPREAD CONVECTION AS THE FIRST DISTURBANCE
MOVES ACROSS WYOMING IN SOME FORM. WEAK WINDS ALOFT MAY RESULT IN
VERY HEAVY RAINFALL AND FLASH FLOODING THROUGH TUESDAY NIGHT.
TEMPERATURES WILL NOT CHANGE MUCH WITH A SUBTROPICAL AIRMASS OVER
THE REGION. EXPECT HIGHS IN THE UPPER 70S TO UPPER 80S...WHICH
WILL BE NEAR OR SLIGHTLY LOWER THAN AVERAGE. KEPT TEMPERATURES A
FEW DEGREES BELOW MOS DUE TO AN OBSERVED WARM BIAS WITH SOUTH TO
SOUTHEAST WINDS ACROSS THE HIGH PLAINS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY EVENING)
ISSUED AT 1120 PM MDT FRI AUG 1 2014

VFR CONDITIONS WILL PREVAIL AT ALL AERODROMES THROUGH THE FORECAST
PERIOD. SKIES FOR THE MOST PART WILL BE MOSTLY CLEAR TO PARTLY CLOUDY.
WINDS WILL BE VARIABLE WITH SPEEDS 10 KT OR LESS.

&&

.FIRE WEATHER...

WARM AND MOSTLY DRY CONDITIONS ARE EXPECTED FOR THE DISTRICT
THROUGH THE WEEKEND AS AN UPPER LEVEL RIDGE OF HIGH PRESSURE REMAINS
OVER THE REGION. MINIMUM HUMIDITIES ARE EXPECTED TO DROP INTO THE
UPPER TEENS TO UPPER 20S...WITH 30 PERCENTS IN THE MOUNTAINS. WINDS
WILL REMAIN LIGHT OVERALL...WITH A FEW LOCATIONS ALONG AND WEST OF
THE LARAMIE RANGE GUSTING 15 TO 25 MPH IN THE AFTERNOONS. THERE
REMAINS A SLIGHT CHANCE FOR ISOLATED THUNDERSTORMS THROUGH EARLY
THIS EVENING FOR LOCATIONS WEST OF THE LARAMIE RANGE AND ALSO ALONG
THE PINE RIDGE. THIS ACTIVITY IS NOT EXPECTED TO PRODUCE MUCH
RAIN...WITH AMOUNTS OF ONLY A COUPLE HUNDREDTHS TO ONE TENTH OF AN
INCH. A MUCH BETTER CHANCE OF MORE SUBSTANTIAL PRECIPITATION WILL
OCCUR MONDAY THRU WEDNESDAY OF NEXT WEEK.

&&

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

$$

SHORT TERM...RJM
LONG TERM...TJT
AVIATION...JAMSKI
FIRE WEATHER...RJM






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