Area Forecast Discussion
Issued by NWS Cheyenne, WY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS65 KCYS 242338
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
538 PM MDT SUN AUG 24 2014

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 345 PM MDT SUN AUG 24 2014

QUIET DAY TODAY WITH FAIR WEATHER CU DEVELOPING ACROSS THE AREA.
DEEP MIXING AND GUSTY WESTERLY WINDS HAVE RESULTED IN QUITE A BIT
OF DRIER AIR ALOFT MIXING DOWN TO THE SURFACE THIS
AFTERNOON...WITH NO DEEP CONVECTION OBSERVED. THE UPPER LEVEL LOW
WHICH BROUGHT RAIN AND TSTORMS TO THE AREA THE LAST FEW DAYS HAS
MOVED INTO NORTH DAKOTA AND WILL EVENTUALLY PUSH INTO
CANADA...WHILE THE NEXT WEATHER CONCERN FOR THIS WEEK IS CURRENTLY
DIGGING SOUTH ACROSS THE PACIFIC NORTHWEST. THIS IS THE NEXT UPPER
LEVEL TROUGH TO LIKELY IMPACT THE FORECAST AREA AND WILL EVENTUALLY
BECOME AN UPPER LEVEL LOW NEAR THE CENTRAL ROCKY MOUNTAINS BY THE
MIDDLE OF THE WEEK. BEFORE THEN...THIS SYSTEM WILL PRIMARILY ALLOW
THE JET STREAM TO SHIFT BACK TO THE NORTH AND INTENSIFY OVER THE
AREA TONIGHT. THERE IS A POTENTIAL FOR NOCTURNAL
CONVECTION...INCLUDING THUNDERSTORMS...TONIGHT ACROSS THE SOUTHERN
HALF OF THE FORECAST AREA...MAINLY SOUTH OF THE NORTH PLATTE RIVER
VALLEY.

THE UPPER LEVEL TROUGH WILL DIG SOUTH INTO THE GREAT BASIN ON
MONDAY. MODELS HAVE CONTINUED TO TREND SLOWER AND MORE AMPLIFIED
WITH THIS SYSTEM OVER THE LAST 3 DAYS AS THE TROUGH BECOMES A
CLOSED LOW SOMEWHERE BETWEEN NORTHERN NEVADA AND NORTHWEST
COLORADO. THE ECMWF AND GEM CONTINUE TO BE THE SLOWEST...WITH THE
GFS AND NAM NOT TOO FAR BEHIND NOW SINCE BOTH SOLUTIONS ARE
TRENDING TOWARDS THE ECMWF. WITH DECENT LOW TO MIDLEVEL
INSTABILITY...MOISTURE ADVECTION...AND CAPE OVER 1000
J/KG...EXPECT AFTERNOON SHOWERS AND TSTORMS TO DEVELOP ACROSS MOST
OF THE AREA. WITH THE LACK OF A DEFINED SHORTWAVE...DO NOT EXPECT
WIDESPREAD COVERAGE. IN FACT...MOST OF THE PANHANDLE MAY NOT SEE
ANY ACTIVITY AT ALL DUE TO THE CAP INVERSION AT 750 MB. KEPT
ISOLATED TSTORMS OVER THAT AREA AT BEST DURING THE AFTERNOON...BUT
MAY SEE AN INCREASE IN SHOWERS AND TSTORMS IN THE EVENING HOURS. A
FEW THUNDERSTORMS MAY BECOME STRONG OVER SOUTHEAST WYOMING. HIGH
TEMPERATURES WILL STRUGGLE TO REACH THE MID TO UPPER 70S ACROSS
MOST OF THE AREA DUE TO INCREASING SOUTHEAST WINDS.

SLOW MOVING CLOSED LOW WILL BARELY MAKE IT INTO WESTERN UTAH BY
TUESDAY...WITH ANOTHER DAY OF THUNDERSTORMS EXPECTED. TUESDAY
LOOKS TO BE A RATHER WET DAY AND ON THE COOL SIDE. ALTHOUGH THE
MAIN LOW WILL BE WELL TO THE WEST...MODELS INDICATE A POTENT
SHORTWAVE DISTURBANCE MOVING NORTHWARD OVER THE AREA. THE POSITION
AND TIMING OF THIS DISTURBANCE WILL INDICATE WHICH AREAS RECEIVE
LOCALLY HEAVY RAINFALL AND THE POTENTIAL FOR SEVERE TSTORMS.
INCREASED POP BETWEEN 40 TO 70 PERCENT ACROSS SOUTHEAST WYOMING ON
TUESDAY/TUESDAY EVENING. WESTERN NEBRASKA WILL STILL BE STRUGGLING
WITH A STRONG CAP INVERSION...SO KEPT POP BELOW 25 PERCENT FROM
SIDNEY TO CHADRON.

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

12Z MODELS HAVE COME INTO SOME AGREEMENT WITH THE UPPER LEVEL LOW
THAT IS EXPECTED TO TRACK ACROSS THE ROCKIES ON WEDNESDAY AND
THURSDAY. AS IT STANDS...MODELS CONTINUE TO FAVOR THE SLOWER
EAST-SOUTHEAST PROGRESSION OF THE UPPER LOW...TRACKING IT OVER THE
ROCKIES THROUGH THURSDAY AND INTO THE CENTRAL PLAINS FRIDAY. THUS
WILL CONTINUE TO RELY MORE ON THIS SLOWER SOLUTION FOR THE EXTENDED
FORECAST. TEMPS WILL REMAIN BELOW AVERAGE WEDNESDAY AND THURSDAY
WITH AT LEAST A CHANCE FOR SCATTERED SHOWERS AND T-STORMS AS THE
UPPER LOW MOVES ACROSS WY/CO ON WEDNESDAY. WILL SEE A STEADY
DECREASE IN COVERAGE FROM WEST TO EAST THURSDAY. PWATS ARE PROGGED
TO BE 0.75 TO 1" OR MORE...AND WITH FAIRLY LIGHT STEERING FLOW OF 10
TO 15 KTS IN PLACE...THIS ACTIVITY COULD BE SLOW MOVING AND PRODUCE
HIGH RAIN RATES. THEREFORE FLOODING WILL BE THE MAIN CONCERN WITH
THIS SYSTEM. MODELS SHOW H7 TEMPS DROPPING TO 3C OVER THE MOUNTAINS
ON WEDNESDAY AS THE LOW CENTER MOVES OVERHEAD...SO ITS VERY POSSIBLE
THE HIGH ELEVATIONS ABOVE 10KFT WILL SEE SNOW MIXED IN WITH RAIN.
THIS SYSTEM WILL SLOWLY DEPART THE REGION THROUGH THE WEEKEND WITH A
WEAK RIDGE BUILDING IN FROM THE WEST FOR FRIDAY AND SATURDAY. A MUCH
DRIER AIRMASS WILL MOVE IN WITH THE RIDGE SO CHANCES FOR AFTN
SHOWERS AND STORMS WILL BE LOW THROUGH SATURDAY NIGHT. BREEZY
CONDITIONS ARE LIKELY ON SATURDAY AS THE LEESIDE SFC PRESSURE TROUGH
DEEPENS IN ADVANCE OF THE NEXT SYSTEM DIGGING INTO THE PAC NW FRI
NIGHT INTO SATURDAY. TEMPS WILL WARM BACK TO MORE NORMAL READINGS
FOR THIS TIME OF YEAR BY SATURDAY AS WELL.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY AFTERNOON)
ISSUED AT 533 PM MDT SUN AUG 24 2014

DRY CONDITIONS INITIALLY ACROSS SOUTHERN WYOMING AND NEBRASKA
PANHANDLE WITH GUSTY WEST WINDS EASING SOME BY SUNSET. GOING TO
SEE AN INCREASE IN CONVECTION FROM THE SOUTH AS MONSOONAL
MOISTURE RETURNS TONIGHT. GOING TO SEE SOME WIDELY SCATTERED
THUNDERSTORMS ACROSS THE SOUTHER LARAMIE RANGE THAT COULD IMPACT
THE KCYS AND KLAR TERMINALS LATER THIS EVENING. SHOWERS AND
THUNDERSTORMS SHOULD CONTINUE TO INCREASE IN COVERAGE MONDAY AND
IMPACT ALL TERMINALS DURING THE AFTERNOON HOURS.

&&

.FIRE WEATHER...
ISSUED AT 245 PM MDT SUN AUG 24 2014

NO FIRE WEATHER CONCERNS THIS WEEK DUE TO THE UNSETTLED WEATHER
PATTERN OVER THE AREA. AFTER A RATHER DRY DAY ON SUNDAY...MOISTURE
WILL QUICKLY RETURN TO THE AREA TONIGHT. MINIMUM RELATIVE
HUMIDITIES WILL TREND HIGHER...BETWEEN 30 TO 50 PERCENT ALONG
WITH EXCELLENT RECOVERIES OVERNIGHT. TEMPERATURES WILL BE COOLER
THAN NORMAL ACROSS MOST LOCATIONS THROUGH AT LEAST THURSDAY.

&&

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

$$

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






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.