Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 201634
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1034 AM MDT WED AUG 20 2014

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 350 AM MDT WED AUG 20 2014

INITIAL SHORTWAVE TROUGH ALOFT MOVES ACROSS OUR COUNTIES
EARLY IN THE DAY...WITH A WEAKER...SECONDARY SHORTWAVE TROUGH
APPROACHING OUR WESTERN COUNTIES IN THE LATE AFTERNOON. SOME LOW
LEVEL DRYING NOTED IN THE WAKE OF THE MORNING SHORTWAVE TROUGH...
THOUGH IT APPEARS THERE WILL BE ENOUGH LOW AND MID LEVEL MOISTURE
THIS AFTERNOON TO SPARK ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS...MOST NUMEROUS WEST OF INTERSTATE 25.

TONIGHT...SHOWERS AND THUNDERSTORMS ENDING IN THE EVENING WITH THE
LOSS OF DAYTIME HEATING AND ABSENCE OF ANY OTHER LIFTING MECHANISMS.

THURSDAY...SOUTHWEST FLOW ALOFT CONTINUES AND WITH ADEQUATE LOW AND
MID LEVEL MOISTURE IN PLACE...WILL SEE ISOLATED LATE DAY
THUNDERSTORMS ALONG AND WEST OF A LUSK TO CHEYENNE LINE.

THURSDAY NIGHT...WEAK COLD FRONT ENTERS FROM THE NORTH...THOUGH WITH
MINIMAL LOW AND MID LEVEL MOISTURE...RAIN CHANCES WILL BE SLIM. LATE
IN THE NIGHT...WILL GO WITH ISOLATED SHOWERS AFTER MIDNIGHT EAST OF
A DOUGLAS TO SIDNEY LINE IN LOW LEVEL CONVERGENCE BOUNDARY.

FRIDAY...INCREASED CHANCE FOR SHOWERS AND THUNDERSTORMS OVER
THURSDAY AS A NEGATIVELY TILTED SHORTWAVE TROUGH ALOFT PROPAGATES
ACROSS OUR WESTERN NEBRASKA COUNTIES...WITH ENHANCED SOUTHEAST LOW
LEVEL WINDS ADVECTING MOISTURE IN...AND PROVIDING MECHANICAL LIFT TO
HELP GENERATE THUNDERSTORMS.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 350 AM MDT WED AUG 20 2014

00Z MEDIUM RANGE GUIDANCE ARE CONSISTENT IN SWINGING AN UPPER
TROUGH THRU THE NRN ROCKIES OVR THE WEEKEND. THIS IS AN EARLY
INDICATION OF THE SEASONAL PATTERN CHANGE THAT WILL CONTINUE OVR
THE NEXT FEW MONTHS. SATURDAY STILL LOOKS RELATIVELY WARM IN THE
PREFRONTAL AIR MASS...ESPECIALLY OVR THE ERN PLAINS. MODELS PROG
1000-1500 J/KG AHEAD OF THE FRONT SATURDAY AFTERNOON. THE
FAVORABLE THERMODYNAMIC PROFILE COMBINED WITH THE PROXIMITY OF RRQ
OF A JET STREAK SUGGESTS AT LEAST THE POSSIBILITY OF A FEW
STRONGER STORMS OVR THE PLAINS SATURDAY AFTERNOON. OF
COURSE...MUCH OF THIS SCENARIO IS DEPENDENT UPON THE CURRENT
TIMING OF LATE SATURDAY AND SATURDAY EVENING FROPA. CONVECTION
WILL TURN MORE SHOWERY IN THE WAKE OF THE FRONT SATURDAY NIGHT.
SUNDAY WILL BE NOTICEABLY COOLER POST-FRONTAL WITH HIGHS ONLY
REACHING 70S AT MOST LOCATIONS. LEFT MOSTLY SHOWER CHANCES ALONG
WITH ISOLD THUNDER MENTION GOING FOR SUNDAY. THIS WILL DEPEND UPON
JUST HOW MUCH CLEARING OCCURS. TEMPERATURES RETURN TO MORE
SEASONAL VALUES FOR MON-TUE TIMEFRAME. HARD TO REMOVE MENTION OF
DAILY AFTERNOON AND EVENING CONVECTION EARLY NEXT WEEK AS
PERSISTENT SOUTHWEST FLOW EJECTS IMPOSSIBLE TO TIME EMBEDDED
SHORTWAVES. PRECIP DEFINITELY WONT BE AN ALL DAY OCCURRENCE...BUT
CANT RULE OUT ITS POSSIBILITY MAINLY DURING THE AFTERNOON AND
EVENING HOURS. THE PATTERN LOOKS TO TREND DRIER FOR THE LATTER
HALF OF NEXT WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY MORNING)
ISSUED AT 1033 AM MDT WED AUG 20 2014

FOLLOWED LATEST HRRR GUIDANCE FOR TIMING ON SHOWERS AND
THUNDERSTORMS FOR SOUTHEAST WYOMING AND NEBRASKA PANHANDLE
AIRPORTS THIS AFTERNOON. HRRR HAS BEEN DOING WELL ON THE EARLY
MORNING CONVECTION...SO SEE NO REASON TO DEVIATE.

&&

.FIRE WEATHER...
ISSUED AT 350 AM MDT WED AUG 20 2014

HUMIDITIES AND WINDS WILL REMAIN BELOW CRITICAL THRESHOLDS THE
NEXT FEW DAYS...THUS MINIMAL FIRE WEATHER CONCERNS.

&&

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

$$

SHORT TERM...RUBIN
LONG TERM...HAHN
AVIATION...CLAYCOMB
FIRE WEATHER...RUBIN





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