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000
FXUS65 KCYS 121807
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1207 PM MDT SUN MAY 12 2013

.SHORT TERM...(TODAY AND MONDAY NIGHT)

ISSUED AT 200 AM MDT SUN MAY 12 2013

LOTS OF FORECAST CHALLENGES WITH TODAYS FORECAST PACKAGE. WE HAVE
FIRE WEATHER CONCERNS AS WELL AS HYDRO ISSUES WITH THE UPCOMING
BOUT OF WARM TEMPERATURES.

CURRENTLY...BOUNDARY THAT WAS SOUTH OF THE CHEYENNE CWFA YESTERDAY
MORNING IS NOW LOCATED TO THE NORTHEAST OVER WESTERN SOUTH DAKOTA.
LATEST RADAR IMAGERY SHOWING SOME ELEVATED RETURNS ACROSS CARBON
AND ALBANY COUNTIES. PRETTY SURE NONE OF THIS IS REACHING THE
GROUND AND WILL CONTINUE THE 0 POPS IN THE FORECAST.

UPPER RIDGE STILL FORECAST TO BUILD RATHER RAPIDLY OVER SOUTHERN
WYOMING TODAY WITH 700MB TEMPERATURES INCREASING FROM 0C YESTERDAY
AFTERNOON TO +6C THIS AFTERNOON ACROSS THE PANHANDLE. LOOKS LIKE A
VERY WARM DAY WITH WIDESPREAD 70S IN SOUTHEAST WYOMING AND 80S IN
THE PANHANDLE. MODELS CONTINUE TO SHOW SOME LIGHT QPF OVER
SOUTHERN CARBON...ALBANY AND LARAMIE COUNTIES THIS AFTERNOON.
CONTINUED THE LOW END CHANCE POPS FOR THE MOUNTAINS. LOWER
ELEVATIONS SUCH AS LARAMIE AND CHEYENNE SHOULD REMAIN DRY.

BY MONDAY AFTERNOON...700MB TEMPERATURES EXPECTED TO CLIMB TO +12C
ACROSS MUCH OF SOUTHEAST WYOMING...LEADING TO THE WARMEST
TEMPERATURES WE HAVE SEEN SO FAR THIS YEAR. WIDESPREAD 90S IN THE
PANHANDLE AND 80S IN SOUTHEAST WYOMING LOOK TO BE COMMON MONDAY
AFTERNOON.

BY MONDAY AFTERNOON...THE UPPER RIDGE AXIS LOOKS TO SHIFT EAST.
BOTH THE GFS AND ECMWF CONTINUE TO FORECAST A SHORTWAVE MOVING
THROUGH MONTANA AND SOUTHERN CANADA. THE GFS SHOWS A MORE SOUTHERN
TRACK OF THE SHORTWAVE THROUGH CENTRAL MONTANA...WHILE THE ECMWF
SHOWS THE MORE NORTHERLY TRACK. IN EITHER CASE...700MB WINDS WILL
BE ON THE INCREASE. ECMWF FORECASTING 30KTS AT 700MBS WHILE THE
GFS SHOWING CLOSE TO 45KTS. WE SHOULD STAY WELL MIXED WITH THESE
WINDS AND OVERNIGHT LOWS MAY ONLY FALL INTO THE 50S FOR MOST
LOCATIONS. NEEDLESS TO SAY...OVERNIGHT HUMIDITY RECOVERIES MONDAY
NIGHT WILL BE POOR. WE ARE LOOKING AT MAX HUMIDITIES ONLY IN THE
MID 40S TO MAYBE 50 PERCENT...SETTING UP THE CRITICAL FIRE WEATHER
CONDITIONS FOR TUESDAY.

.LONG TERM...(TUESDAY THROUGH SATURDAY NIGHT)

ISSUED AT 230 AM MDT SUN MAY 12 2013

MODELS IN GOOD AGREEMENT THROUGH NEXT WEEK...SHOWING WARM
TEMPERATURES AND GENERALLY DRY CONDITIONS ACROSS SOUTHEAST WYOMING
AND WESTERN NEBRASKA THROUGH FRIDAY. UPPER LEVEL RIDGE AXIS WILL
SHIFT INTO THE GREAT PLAINS AND FLATTEN BY THE MIDDLE OF THE
WEEK...WITH ZONAL FLOW EXPECTED BY WEDNESDAY AS A WEAK COOL FRONT
MOVES SOUTHWARD ACROSS THE AREA. THIS FRONT WILL BEGIN TO PUSH
ACROSS WYOMING LATE ON TUESDAY AS A PACIFIC STORM SYSTEM PUSHES
ACROSS MONTANA...BUT WITH 700MB TEMPERATURES REMAINING OVER
10C...EXPECT DAYTIME HIGHS IN THE 80S TO LOW 90S ACROSS THE HIGH
PLAINS WITH UPPER 70S IN THE VALLEYS WEST OF THE LARAMIE RANGE.
COOLER TEMPERATURES ARE EXPECTED ON WEDNESDAY...BUT WILL STILL
REMAIN NEAR NORMAL OR SLIGHTLY ABOVE NORMAL FOR THIS TIME OF THE
YEAR. BREEZY OR WINDY CONDITIONS ARE EXPECTED TUESDAY AND TUESDAY
NIGHT...ESPECIALLY ACROSS SOUTHEAST WYOMING WHERE GUSTS UP TO 45
MPH ARE POSSIBLE. PRECIPITATION CHANCES THROUGH THURSDAY WILL
REMAIN MINIMAL...WITH A SLIGHT CHANCE OF TSTORMS NEAR THE LARAMIE
RANGE...INCLUDING THE ADJACENT FOOTHILLS AND VALLEYS. TEMPERATURES
WILL INCREASE BACK INTO THE 70S AND LOW 80S BY THE END OF THE
WEEK AS SOUTHWEST FLOW ALOFT REDEVELOPS ACROSS WYOMING AND
COLORADO. MODELS THEN INDICATE A PACIFIC STORM SYSTEM MOVING
ONSHORE BY LATE THURSDAY...AND EVENTUALLY PUSHING ACROSS THE GREAT
BASIN REGION AND INTO THE ROCKIES BY NEXT WEEKEND. INCREASED POP
BETWEEN 20 TO 40 PERCENT BY SATURDAY WITH SHOWERS BECOMING
WIDESPREAD AND SCATTERED TSTORMS POSSIBLE. ALSO...LOWERED
TEMPERATURES NEXT WEEKEND SINCE MODELS ARE SHOWING A RATHER CHILLY
AIRMASS MOVING INTO WYOMING AND THE HIGH PLAINS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY MORNING)
ISSUED AT 1201 PM MDT SUN MAY 12 2013

VFR CONDITIONS THROUGH THE TAF PERIOD. REMOVED THE MENTION OF
ISOLATED SHOWERS THIS AFTERNOON FROM THE TAFS AS INSTABILITY LOOKS
QUITE LIMITED. JUST EXPECTING SOME SCATTERED CUMULUS WITH BASES
8-11 KFT AGL. GUSTS TO 20-25 KTS WILL BE POSSIBLE THROUGH THE
EARLY EVENING WITH THE DEEP MIXING IN PLACE...ESPECIALLY ACROSS
SOUTHEAST WY. WINDS SHOULD SUBSIDE SHORTLY AFTER SUNSET.

&&

.FIRE WEATHER...
ISSUED AT 200 AM MDT SUN MAY 12 2013

THE SOUTHERN LARAMIE RANGE COULD STILL SEE SOME SCATTERED SHOWERS
AND THUNDERSTORMS THIS AFTERNOON. ELSEWHERE...LOOK FOR WARMER AND
DRIER WEATHER ACROSS MOST OF SOUTHEAST WYOMING AND NEBRASKA
PANHANDLE. A LOW PRESSURE SYSTEM IS STILL ON TRACK TO MOVE THROUGH
NORTHERN MONTANA MONDAY INTO TUESDAY. IMPACT HERE ACROSS SOUTHEAST
WYOMING AND NEBRASKA PANHANDLE WILL BE AN INCREASE IN WESTERLY
WINDS. VERY WARM TEMPERATURES WILL COMBINE WITH THESE STRONG WINDS
TO CREATE CRITICAL FIRE WEATHER CONDITIONS. ESPECIALLY FOR THE
NEBRASKA PANHANDLE WHERE FUELS ARE STILL REPORTED AS DRY AND
CAPABLE OF PROVIDING RAPID FIRE GROWTH. ELSEWHERE...WE LOOK TO BE
IN GREEN UP HERE ACROSS SOUTHEAST WYOMING...SO IMPACTS WILL BE
LESS...BUT WE WILL STILL SEE THE LOW HUMIDITIES AND STRONG WINDS.

&&

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

$$

SHORT TERM...CLAYCOMB
LONG TERM...TJT
AVIATION...FINCH
FIRE WEATHER...CLAYCOMB