Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 280528
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1128 PM MDT MON OCT 27 2014

.UPDATE...
ISSUED AT 747 PM MDT MON OCT 27 2014

NO CHANGES TO THE FORECAST FOR TONIGHT. IT WILL BE ONE OF THE
COLDEST NIGHTS YET THIS SEASON BUT STILL ONLY SLIGHTLY BELOW
AVERAGE FOR LATE OCTOBER. CLEAR SKIES WILL PREVAIL MUCH OF TONIGHT
WITH SOME INCREASING HIGH CLOUDS LATE. LOWS TONIGHT WILL MAINLY BE
IN THE 20S OUTSIDE OF THE MOUNTAINS WHERE LOWS WILL BE IN THE
TEENS.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 300 PM MDT MON OCT 27 2014

AFTERNOON WATER VAPOR LOOP SHOWED THE UPPER LOW AND ATTENDANT
TROUGH MOVING ACROSS THE DAKOTAS AND NEBRASKA. A COLD POCKET
ALOFT HAS STEEPENED LAPSE RATES OVER SOUTHEAST WYOMING AND
WESTERN NEBRASKA PANHANDLE...WITH WIDELY SCATTERED RAIN/SNOW
SHOWERS DEVELOPING. CAPES ARE LOW /100-200 J/KG/ SO NOT
EXPECTING ANY THUNDER WITH THIS CONVECTION...WHICH WILL LINGER
THROUGH LATE AFTERNOON BEFORE DISSIPATING. 700MB TEMPERATURES
AROUND -5C WITH PARTIAL INSOLATION WILL YIELD MAX TEMPERATURES
IN THE 40S TO LOWER 50S. GUSTY NORTHWEST WINDS OF 25 TO 35 MPH
ARE MAKING IT FEEL 10 DEGREES COLDER.

12Z NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH THE
OVERALL LARGE SCALE PATTERN. THE NORTH CENTRAL UPPER LOW/TROUGH
WILL TRACK EAST ACROSS THE UPPER MIDWEST AND GREAT LAKES AND NEW
ENGLAND THROUGH THE SHORT TERM. TO THE WEST...A BROAD UPPER RIDGE
WILL MAINTAIN A DRY WEST TO NORTHWEST FLOW ALOFT FOR THE CWA.
SURFACE HIGH PRESSURE WILL EXPAND FROM THE INTERMOUNTAIN WEST
ACROSS THE ROCKIES AND HIGH PLAINS. WITH FAIR SKIES AND DIMINISHING
WINDS TONIGHT...LOW TEMPERATURES WILL BOTTOM OUT IN THE UPPER
TEENS TO UPPER 20S.

THE PRESSURE GRADIENT WILL BE WEAKER TUESDAY COMPARED TO TODAY...
WITH BREEZY WESTERLY WINDS DEVELOPING FOR MUCH OF SOUTHEAST WYOMING
DURING THE AFTERNOON. 700MB TEMPERATURES RECOVER TO AROUND -3C
TUESDAY AFTERNOON WITH MAX TEMPERATURES IN THE 50S EAST OF THE
LARAMIE RANGE. AREAS TO THE WEST CAN EXPECT HIGHS IN THE 30S AND
40S. LIGHT TO MODERATE SOUTHWESTERLY WINDS AND SOME HIGH CLOUDINESS
WILL RESULT IN MILDER TEMPERATURES TUESDAY NIGHT WITH LOWS FROM
THE MID 20S TO MID 30S.

LEE-SIDE SURFACE TROUGH DEVELOPS OVER THE HIGH PLAINS WEDNESDAY...
SETTING UP A TIGHTER PRESSURE GRADIENT ACROSS SOUTHEAST WYOMING.
WESTERLY WINDS INCREASE WITH GUSTS TO 40 MPH...MAINLY ALONG AND
WEST OF THE LARAMIE RANGE. DOWNSLOPE FLOW...INCREASING MID LEVEL
THICKNESSES AND 700MB TEMPERATURES AROUND +1C WILL RESULT IN HIGH
TEMPERATURES IN THE 60S EAST OF THE LARAMIE RANGE. LOW TEMPERATURES
WEDNESDAY NIGHT WILL BE IN THE 30S.

.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 245 PM MDT MON OCT 27 2014

MILD AND DRY WEATHER EXPECTED OVER THE CWA THURSDAY THROUGH MOST OF
SATURDAY AS AN UPPER RIDGE TRANSLATES EASTWARD ACROSS THE REGION...
WITH A NICE 576DM THICKNESS RIDGE OVER THE HIGH PLAINS SATURDAY.
A POTENT UPPER TROUGH WILL THEN MOVE OUT OF THE SW PART OF THE
CONUS AND ACROSS WY SAT NIGHT...PROGRESSING INTO THE NORTHERN
PLAINS SUNDAY CLOSING OFF AN UPPER LOW OVER THAT AREA. AS IT
PASSES BY IT SHOULD BRING A ROUND OF SHOWERS WITH SOME MTN SNOW
SAT NIGHT AND SUNDAY ALONG WITH A COLD FRONTAL PASSAGE. TEMPS
WILL BE COOLER SUNDAY AND MONDAY ALONG WITH SOME WINDINESS THOUGH
NOT DRAMATICALLY COLDER AS AIR MASS WILL BE OF PACIFIC ORIGIN...
WITH TEMPS CLOSER TO SEASONAL NORMS. CONTINUED COOL AND DRY MONDAY
AS SFC HIGH PRESSURE BUILDS IN FROM THE WEST.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1125 PM MDT MON OCT 27 2014

VFR. WINDS GUSTING 15 TO 25 KNOTS TUESDAY AFTERNOON...OTHERWISE
LIGHT WINDS.

&&

.FIRE WEATHER...
ISSUED AT 230 PM MDT MON OCT 27 2014

NO FIRE WEATHER CONCERNS ARE ANTICIPATED THIS WEEK. MINIMUM
RELATIVE HUMIDITIES WILL RANGE FROM 20 TO 25 PERCENT. WESTERLY
WINDS WILL BE BREEZY TUESDAY AFTERNOON FOR MUCH OF SOUTHEAST
WYOMING. A DEEPENING LEE-SIDE SURFACE TROUGH WILL RAISE WINDS
WITH GUSTS TO 40 MPH WEDNESDAY AFTERNOON. WINDS WILL BE LIGHTER
ACROSS WESTERN NEBRASKA. NO PRECIPITATION IS FORECAST UNTIL
SATURDAY NIGHT AND SUNDAY WITH THE NEXT PACIFIC LOW PRESSURE
TROUGH.

&&

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

$$

UPDATE...SML
SHORT TERM...MAJ
LONG TERM...RE
AVIATION...RUBIN
FIRE WEATHER...MAJ



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