Area Forecast Discussion
Issued by NWS Cheyenne, WY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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 240437
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1037 PM MDT MON MAR 23 2015

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 250 PM MDT MON MAR 23 2015

THE MAIN CONCERN WITH THIS FORECAST PACKAGE WILL BE HIGH WIND
POTENTIAL ACROSS PORTIONS OF SOUTHEAST WYOMING BEGINNING LATE
TONIGHT AND CONTINUING THROUGH TUESDAY EVENING.

THIS AFTERNOON AND TONIGHT:
LATEST WATER VAPOR LOOP WAS SHOWING THE DRY SLOT PUSHING THROUGH
EASTERN COLORADO WITH A JET STREAK PLOWING THROUGH THAT REGION AS
WELL. LATEST RADAR LOOP WAS SHOWING SOME SHOWERS AND ISOLATED
THUNDERSTORMS DEVELOPING ALONG THE SURFACE TROF WHICH EXTENDS INTO
NORTHERN WYOMING WHICH IS ALSO NEAR THE LEFT EXIT REGION OF THE
UPPER LEVEL JET. MOST UNSTABLE CAPES ARE AROUND 100-200J/KG IN
THIS REGION WITH WIND SHEAR VALUES AROUND 30 TO 40 KTS. LAPSE
RATES FROM THE LAPS MODEL ARE QUITE STEEP 8 TO 9 DEG/C.
THEREFORE...WE WOULD NOT BE SURPRISED TO SEE SOME GUSTY WINDS UP
TO 50 MPH ALONG WITH SOME LIGHTNING STRIKES. RADAR LOOP WAS ALSO
SHOWING SOME SCATTERED SHOWERS MOVING INTO CARBON COUNTY. THIS
ACTIVITY COULD FLARE UP AS WELL AND YIELD TO SOME ISOLATED
THUNDERSTORMS WITH GUSTY WINDS. AFTER THIS UPPER LEVEL TROF PASSES
THROUGH...WE WILL SEE THE PRESSURE GRADIENTS BEGIN TO TIGHTEN UP
AS LARGE SCALE SUBSIDENCE MOVES INTO THE PICTURE. AS A RESULT...WE
HAVE UPGRADED THE HIGH WIND WATCH TO A HIGH WIND WARNING FOR THE
WIND PRONE AREAS.

THE SNOW WILL ALSO DEVELOP OVER THE MOUNTAINS THIS EVENING AS THE
UPSLOPE FLOW KICKS IN. WE HAVE NOT ISSUED ANY ADVISORY AT THIS
TIME...BUT IT IS POSSIBLE WE MAY SEE 4 TO 6 INCHES BY TUESDAY
EVENING.

TUESDAY:
WE WENT AHEAD AND INTRODUCED A HIGH WIND WATCH FOR THE LARAMIE
VALLEY AND THE CHEYENNE ZONE GROUP. THIS AREA MAY HAVE GUSTY WINDS
OVERNIGHT MAINLY ASSOCIATED WITH A TIGHT PRESSURE GRADIENT.
HOWEVER...THE STRONGER WINDS ARE EXPECTED AFTER DAYBREAK WHEN WE
START INCREASING THE DEPTH OF THE MIXING LAYER ALONG WITH STRONG
SYNOPTIC SCALE SUBSIDENCE. IT APPEARS LIKE THE BEST CHANCE TO
REACH HIGH WIND WARNING CRITERIA WILL BE IN THE LATE MORNING INTO
THE EARLY AFTERNOON FOR CHEYENNE. MEANWHILE...THE LARAMIE VALLEY
MAY MIX OUT THE QUICKEST AND STAY PERSISTENT THROUGH THE REMAINDER
OF THE DAY.

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 250 PM MDT MON MAR 23 2015

SHORTWAVE IS PROGGED TO DIG SOUTHEASTWARD FROM WY ON TUES NIGHT
INTO COLORADO ON WED. ASSOCIATED WITH THIS UPPER LEVEL SYSTEM...A
COLD FRONT WILL PASS ACROSS THE REGION ON TUES NIGHT WITH COOLER
TEMPS FOR WED. ALL OF THE MODELS GENERATE LIGHT QPF (0.10-0.15
INCHES) ALONG AND WEST OF THE LARAMIE RANGE ON WED MORNING. THIS
WOULD FALL AS SNOW WITH 700MB TEMPS AROUND -10C BY THAT TIME. DID
RAISE POPS INTO THE 50-60 PERCENT RANGE FOR 12-18Z WED. NORTHERLY
FLOW ALOFT WILL REMAIN IN PLACE THROUGH THURS. A WEAKER SHORTWAVE
WILL PASS OVER CENTRAL SOUTH DAKOTA ON THURS WITH A SLIGHT CHANCE
OF SHOWERS MAINLY ACROSS THE NEBRASKA PANHANDLE. WITH GOOD LLVL
MIXING AND 30-35 KTS AT THE TOP OF THE MIXED LAYER...IT WILL BE
BREEZY ACROSS THE PLAINS. TEMPS WILL INCREASE BACK INTO THE 50S BY
FRI AND INTO THE 60S BY SAT. SAT WILL LIKELY BE THE WARMEST DAY AS
SFC WINDS BECOME MORE WESTERLY IN RESPONSE TO PRESSURE FALLS ALONG
THE WY-NE BORDER. A DRY COLD FRONTAL PASSAGE ON SAT NIGHT WILL
CAUSE TEMPS TO FALL 5-10 DEGREES FOR SUNDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1034 PM MDT MON MAR 23 2015

LATEST RADAR SUMMARY SHOWING SHOWERS COMING TO AN END ACROSS THE
SOUTHERN PANHANDLEAND SOUTHEAST WYOMING. CONCERNS ARE FOR STRONG
WINDS TONIGHT AS GUIDANCE DOES SHOW WINDS APPROACHING 45KTS FOR
KLAR AND KRWL TUESDAY MORNING. SEE NO REASON NOT TO GO WITH THESE
STRONG WINDS...THOUGH THEY MAY HOLD OFF UNTIL LATE MORNING AND
PERSIST INTO THE AFTERNOON. STRONG WINDS WILL CREATE VERY
TURBULENT CONDITIONS FOR TAKEOFFS AND LANDINGS FOR OUR SOUTHEAST
WYOMING AIRPORTS THROUGH TUESDAY AFTERNOON...ONCE THE WINDS DO
BEGIN TO BLOW.

&&

.FIRE WEATHER...
ISSUED AT 250 PM MDT MON MAR 23 2015

WE WENT AHEAD AND ISSUED A FIRE WEATHER WATCH FOR THE SOUTHERN
NEBRASKA PANHANDLE TUESDAY AFTERNOON AS DEEP LOW LEVEL MIXING
DEVELOPS ALONG WITH LARGE SCALE SUBSIDENCE. WIND GUSTS TUESDAY
AFTERNOON COULD REACH 40 MPH OUT OF THE WEST-NORTHWEST WITH
RELATIVE HUMIDITY VALUES DROPPING INTO THE 15 TO 20 PERCENT RANGE.
GUSTY WINDS ARE ALSO EXPECTED ON WEDNESDAY AND POSSIBLY THURSDAY
AS CANADIAN HIGH PRESSURE CONTINUES TO INFLUENCE THE PANHANDLE
WHERE THE FUELS ARE CURED.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...HIGH WIND WARNING UNTIL 8 PM MDT TUESDAY FOR WYZ106-110-116-117.

     HIGH WIND WATCH FROM 6 AM MDT TUESDAY THROUGH TUESDAY EVENING
     FOR WYZ115-118.

NE...FIRE WEATHER WATCH FROM 10 AM MDT TUESDAY THROUGH TUESDAY
     EVENING FOR NEZ313.

&&

$$

SHORT TERM...REC
LONG TERM...ZF
AVIATION...GCC
FIRE WEATHER...REC


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