Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 181159
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
459 AM MST TUE NOV 18 2014

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 356 AM MST TUE NOV 18 2014

TODAY...PRIMARY CHALLENGE WILL BE WINDS...AS IS QUITE TYPICAL FOR
OUR NOVEMBER THROUGH MARCH WINDY SEASON. MONDAY DAY SHIFT TEAM SET
THE TABLE WELL WITH AN INHERITED HIGH WIND WATCH THIS AFTERNOON AND
EVENING FOR THE SOUTHERN LARAMIE RANGE FOOTHILLS AND SOUTHERN
LARAMIE RANGE...INCLUDING THE INTERSTATE 80 SUMMIT. UPON CAREFUL
ANALYSIS...AND TO ERR ON THE SIDE OF PUBLIC SAFETY...WE HAVE DECIDED
TO UPGRADE TO A HIGH WIND WARNING FOR THE NOON TO 9 PM TIME
FRAME...ESPECIALLY SINCE INTERSTATE 80 IS ONE OF THE MOST HEAVILY
TRAVELED ROUTES...ESPECIALLY FOR TRUCK AND HIGH PROFILE VEHICLE
TRAVEL.

WITH RESPECT TO WINDS...FAST MOVING POSITIVELY TILTED LOW AMPLITUDE
SHORTWAVE TROUGH ALOFT MOVES OVER OUR COUNTIES THIS AFTERNOON WITH
THE SURFACE TO 500 MB GRADIENTS STRENGTHENING. BY LATE THIS
AFTERNOON...THE LEFT FRONT QUADRANT OF A 100-125 KNOT 300 MB JET
STREAK WILL LIE NORTHWEST TO SOUTHEAST OVER OUR COUNTIES...AND THE
FAVORABLE FRONT RIGHT QUADRANT WILL MOVE OVER OUR WARNING AREA LATE
THIS AFTERNOON AND EVENING. EVEN THOUGH THE STRONGEST 700 MB WINDS
WILL REMAIN WELL EAST OF THE SOUTHERN LARAMIE RANGE...AND EVEN
THOUGH THE 500-300 MB AND 700-500 MB LAYERS QUASIGEOSTROPHIC FORCING
ARE NOT REAL FAVORABLE UNTIL THIS EVENING...OUR LOCAL CRAIG COLORADO
TO CASPER 850 MB HEIGHT GRADIENTS PEAK FROM 60 TO 65 METERS FROM
LATE MORNING TO NOON WITH THE 700 MB GRADIENTS PEAKING NEAR 60
METERS AT MID AFTERNOON...TO ERR ON PUBLIC SAFETY AND ESPECIALLY
WITH THE HIGH TRAVELED HIGH PROFILE INTERSTATE 80 TRAFFIC OVER THE
I-80 SUMMIT...WE HAVE OPTED TO GO WITH A HIGH WIND WARNING.

MILD WEATHER ENTHUSIASTS WILL BE PLEASED AS DESPITE THE SOMETIMES
BRISK WINDS TODAY...TEMPERATURES WILL PEAK ABOVE FREEZING AT MOST
LOCALES.

TONIGHT...RELATIVELY QUIESCENT OVERNIGHT WITH STRONG NORTHWEST FLOW
ALOFT AND DECENT MIXING.

WEDNESDAY...PERPETUAL NORTHWEST FLOW ALOFT CONTINUES WITH PERIODS OF
MIDDLE AND HIGH LEVEL CLOUDS...WITH OPACITY OR THICKNESS
VARIABLE...THOUGH STILL RELATIVELY MILD WITH TEMPERATURES PEAKING
ABOVE FREEZING AT MOST LOCALES.

WEDNESDAY NIGHT...ANOTHER COOL AND QUIESCENT OVERNIGHT AS THE FLOW
ALOFT AND NEAR THE SURFACE RELAXES.

THURSDAY...IF YOU LOVE MILD WEATHER...YOU WILL ENJOY THIS TRANSITION
TO A MORE ZONAL FLOW ALOFT WITH WEAKER FLOW ALOFT AND THUS WEAKER
SURFACE WINDS AND IF THE MIDDLE AND HIGH CLOUD OPACITY...THICKNESS
IS MINIMAL...WE EXPECT TEMPERATURES TO SOAR WELL INTO THE 40S ALONG
AND EAST OF INTERSTATE 25...WITH WIDESPREAD ABOVE FREEZING AND LOWER
40S TEMPERATURES IN THE TYPICALLY COLDER VALLEYS AND HIGHER
ELEVATIONS WEST OF I-25.  NEAR NIL PRECIPITATION CHANCES DUE TO
LIMITED LOW AND MID LEVEL MOISTURE...AND LIFT.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 356 AM MST TUE NOV 18 2014

A RATHER PROGRESSIVE ZONAL PATTERN IS SHAPING UP FOR THE WEEKEND
AS A 150+ KT JET MOVES INTO THE WESTERN CONUS AND TRAVERSES
EASTWARD THROUGH EARLY NEXT WEEK. THE STRONGEST CORE OF WINDS
WILL REMAIN SOUTH OF THE CWA THROUGH THIS TIME...ALTHOUGH SOMEWHAT
DISORGANIZED MIDLEVEL ENERGY AND PACIFIC MOISTURE WILL STREAM
OVERHEAD. FRIDAY WILL BE MOSTLY DRY...MILD AND BREEZY AS AN
INITIAL SHORTWAVE MOVES OVER THE NORTHERN ROCKIES AND DEEPENS THE
LEESIDE PRESSURE TROUGH. A MUCH STRONGER WAVE ON THE CYCLONIC SIDE
OF THE HIGHER JET WINDS WILL MOVE ACROSS THE PAC NORTHWEST AND
INTO THE NORTHERN ROCKIES/PLAINS ON SATURDAY...WITH THE LEESIDE
PRESSURE TROUGH DEEPENING FURTHER AND LIKELY DEVELOPING HIGH WINDS
FOR THE WIND PRONE AREAS OF SOUTHEAST WYOMING. TEMPS WILL SPIKE
INTO THE 50S ACROSS THE WYO/NEB PLAINS ON SATURDAY WITH DOWNSLOPE
WINDS IN PLACE...WITH 30S AND 40S OUT WEST. A PACIFIC COLD FRONT
WILL MOVE ACROSS THE CWA LATE SATURDAY WITH COOLER HIGH TEMPS ON
SUNDAY. CONTINUED BREEZY TO WINDY CONDITIONS ARE EXPECTED OVER A
LARGER PORTION OF OUR COUNTIES BEHIND THE FRONT...ALTHO WINDS WILL
NOT BE QUITE AS STRONG AS SATURDAY. PRECIP CHANCES WILL INCREASE
FROM WEST TO EAST WITH INCREASING MIDLEVEL ENERGY AND FRONTAL
FORCING ON SATURDAY...ALTHO KEPT CHANCES HIGHEST IN THE MOUNTAINS
AND NEARBY VALLEYS WITH MAINLY SLIGHT CHANCE ACROSS THE PLAINS DUE
TO DRIER DOWNSLOPE PROCESSES IN PLACE. THE STRONG UPPER JET WILL
DIG INTO THE SOUTHERN TIER OF STATES SUNDAY AND MONDAY AND WILL
OPEN THE DOOR FOR CHILLY CANADIAN AIR TO FILTER BACK INTO THE CWA.
WILL KEEP SNOW CHANCES IN THE MOUNTAINS THROUGH MONDAY AS
ENERGETIC BUT DISORGANIZED WNW FLOW REMAINS OVER THE ROCKIES. ALL
IN ALL...COULD SEE A STEADY PERIOD OF MOUNTAIN SNOW THROUGH THE
PERIOD WITH MODERATE ACCUMULATIONS LIKELY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 459 AM MST TUE NOV 18 2014

VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD WITH SCT-BKN
150-200 DECK MOVING IN FROM THE NORTH BY LATE THIS MORNING. GUSTY
WINDS WILL BE THE MAIN CONCERN THROUGH THIS TAF PERIOD...WITH WNW
WINDS GUSTING 20 TO 35 KTS ACROSS THE WYO/NEB PLAINS AND WSW GUSTS
30 TO 40 KTS OUT WEST THIS AFTERNOON. WINDS WILL SLOWLY DIMINISH
THIS EVENING.

&&

.FIRE WEATHER...
ISSUED AT 356 AM MST TUE NOV 18 2014

MINIMAL FIRE WEATHER ISSUES OR CONCERNS DUE TO PROJECTED AND
EXPECTED WINDS AND HUMIDITIES.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...HIGH WIND WARNING FROM NOON TODAY TO 9 PM MST THIS EVENING FOR
     WYZ116-117.

NE...NONE.
&&

$$

SHORT TERM...SAR
LONG TERM...RJM
AVIATION...RJM
FIRE WEATHER...SAR



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