Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 192154
AFDCYS

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE CHEYENNE WY
313 PM MDT SAT JUL 19 2014

.SHORT TERM...(TONIGHT THROUGH MONDAY NIGHT)
ISSUED AT 310 PM MDT SAT JUL 19 2014

HOT AND DRY WEATHER CONDITIONS WILL BE THE RULE FOR MOST AREAS OVER
THE NEXT SEVERAL DAYS. RELATIVELY DRY WEST-TO-NORTHWEST FLOW ALOFT
REMAINS IN PLACE ACROSS THE CWA...WITH A FEW NUISANCE DISTURBANCES
EMBEDDED WITHIN THE FLOW PER RECENT WATER VAPOR IMAGERY. EARLY THIS
AFTN...A SFC TROUGH WAS ANALYZED FROM NORTH TO SOUTH ALONG I25. DRY
TO THE WEST WITH WESTERLY DOWNSLOPE...MORE MOIST OVER THE SOUTHERN
PANHANDLE WHERE SOUTHERLY LLVL FLOW IS KEEPING DEWPOINTS IN THE LOW
TO MIDDLE 50S. WEAK LLVL CONVERGENCE COULD HELP TRIGGER AN ISOLATED
SHOWER OR TSTM THROUGH EARLY EVE...SO WILL MAINTAIN ISOLATED POPS
FOR THE EASTERN PLAINS AND THE MOUNTAINS. SHOULD NOT SEE ANYTHING
TOO STRONG WITH MODEST INSTABILITY IN PLACE...BUT CANNOT RULE OUT
SOME GUSTY OUTFLOW WINDS GIVEN INVERTED-V SOUNDING PROFILES. SFC RH
VALUES HAVE FALLEN INTO THE LOWER TEENS OVER CARBON COUNTY THIS AFTN
IN THE PRESENCE OF 35 MPH WIND GUSTS. FUELS ARE FAVORABLE FOR FIRE
GROWTH OVER THE UPPER NORTH PLATTE RIVER BASIN...AND SEE NO REASON
FOR ANY NOTABLE IMPROVEMENT IN THE NEXT FEW HOURS ASIDE FROM A FEW
CUMULUS CLOUDS. ISSUED A RED FLAG WARNING FOR THAT FWZ THROUGH 02Z
THIS EVE.

CONTINUED HOT AND DRY ON SUN AND MON. BOTH THE GFS AND ECMWF SHOW
UPPER LEVEL RIDGING BECOMING ESTABLISHED ACROSS THE CENTRAL ROCKIES
DURING THAT TIME FRAME. 1000-500 HPA THICKNESS VALUES AROUND 582 DM
AND WIDESPREAD H7 TEMPS WELL ABOVE 15C SUGGESTS MANY AREAS WILL SEE
90S TO PERHAPS 100 OVER THE PANHANDLE OVER THE LOWER ELEVATIONS OF
THE PLATTE RIVER VALLEY. SOME OF THE MOS GUIDANCE SHOWS TEMPS ABOVE
95 DEG F FOR CYS BOTH DAYS. THIS IS QUITE POSSIBLE WITH CONTINUED
DOWNSLOPE WARMING...BUT THINKING THERE IS ENOUGH MOISTURE ALOFT TO
AID IN MIDDAY CLOUDS TO INHIBIT SOLAR INSOLATION. FCST HIGHS ARE A
FEW DEGREES LOWER THAN THOSE VALUES FOR THAT REASON. THE LACK OF ANY
SUBSTANTIAL FORCING MECHANISMS SUGGESTS MOST OF THE PCPN THIS PERIOD
SHOULD BE ALONG AND WEST OF THE LARAMIE RANGE. MOIST SOUTHWEST FLOW
IS PROGGED TO DEVELOP BY SUN NIGHT AND MON. COULD SEE SOME NOCTURNAL
CONVECTION ON MON MORNING BEFORE BECOMING MORE WIDESPREAD. HOWEVER
THE LATEST MODEL RUNS ARE TAKING THE BEST 700-300 HPA MOISTURE TO
THE NORTH OF THE CWA. SHOWER AND TSTM COVERAGE IS LOOKING PRETTY
LIMITED YET AGAIN...BUT ENOUGH MODEL SUPPORT TO AT LEAST MAINTAIN
LOW END POPS.

.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 310 PM MDT SAT JUL 19 2014

HIGH PRESSURE CENTERED OVR THE COLORADO/NEW MEXICO STATELINE WILL
MOVE LITTLE FOR THE SECOND HALF OF NEXT WEEK...BUT WILL FLATTEN
SOMEWHAT AS THE STRONGER MID-LEVEL WESTERLIES TURN MORE ZONAL. THE
RESULT FOR THE THE HOT CONDITIONS CONTINUING THRU AT LEAST THE END
OF NEXT WEEK. WED/THU WILL OFFER THE BEST OPPORTUNITIES FOR
AFTERNOON AND EARLY EVENING SHOWER/THUNDERSTORM CHANCES AS BOTH THE
ECMWF AND GFS ARE CONSISTENT IN TRACKING A COUPLE OF SHORTWAVES AND
ASSOCIATED MID-LEVEL MOISTURE THRU THE CWFA. IT LOOKS LIKE
CONVECTION WILL DEVELOP OVR THE HIER TERRAIN OF SE WYOMING BOTH
AFTERNOONS...BEFORE SLIDING EAST ONTO THE PLAINS THRU THE EVENING
HOURS. CONVECTION WONT BE PARTICULARLY WIDESPREAD EITHER
DAY...LIMITED BY WARM MID-LEVEL TEMPERATURES. H7 TEMPS HOVER BETWEEN
17-20C THRU MUCH OF THE PERIOD...WHICH WILL YIELD HIGHS IN THE UPPER
80S AND 90S. MODELS ARE SHOWING TEMPS COOLING A TAD FOR
FRI/SAT...BUT AM NOT CONVINCED IT WILL BE AS MUCH AS MODELS ARE
ADVERTISING. EITHER WAY...THE FRI/SAT PERIOD LOOKS DRY AS THE
POST-FRONTAL AIR MASS SHOULD BE ENOUGH TO INHIBIT CONVECTION
CHANCES...IF ONLY BRIEFLY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1138 AM MDT SAT JUL 19 2014

AN UNEVENTFUL AVIATION PERIOD SHAPING UP WITH VFR CONDITIONS
PREVAILING. BAND OF HIGH-LEVEL CIRRUS PASSING OVERHEAD EARLY THIS
AFTERNOON WILL GIVE WAY TO A FEW SHALLOW AFTERNOON BUILDUPS.
LIMITED MOISTURE AVAILABLE WILL KEEP ALL OF THE ACTIVITY VERY
HIGH BASED...BETWEEN 12-15KFT AGL. WOULD NOT RULE OUT A FEW
SPRINKLES FROM THIS ACTIVITY LATE THIS AFTERNOON...BUT CONFIDENCE
IS NOT ENOUGH TO INCLUDE ANY MENTION IN THE TERMINALS AT THIS
TIME. WEST/SOUTHWEST WINDS WILL OCCUR AT SE WY SITES AND
SOUTH/SOUTHEAST WINDS OVR THE WRN NEBRASKA PANHANDLE LOCATIONS.

&&

.FIRE WEATHER...
ISSUED AT 310 PM MDT SAT JUL 19 2014

HOT AND DRY FOR THE NEXT SEVERAL DAYS. CRITICAL FIRE CONDITIONS WILL
CONTINUE FOR THE UPPER NORTH PLATTE BASIN THROUGH 800 PM ON SATURDAY
EVENING WITH HUMIDITIES AROUND 15 PERCENT AND GUSTS TO 35 MPH. A RED
FLAG WARNING IS IN EFFECT. WINDS WILL DIMINISH AROUND SUNSET. MOST
AREAS WILL SEE AFTERNOON HUMIDITY VALUES FALL BELOW 20 PERCENT ON
SUNDAY AND MONDAY. WINDS ARE GENERALLY EXPECTED TO REMAIN BELOW
CRITICAL THRESHOLDS...EXCEPT ALONG AND WEST OF THE LARAMIE RANGE ON
MONDAY WHERE GUSTS COULD EXCEED 25 MPH. THERE IS A CHANCE OF
SHOWERS AND WEAK TSTMS EACH AFTERNOON THROUGH MON...MAINLY OVER THE
MOUNTAINS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR WYZ306.

NE...NONE.
&&

$$

SHORT TERM...HAMMER
LONG TERM...HAHN
AVIATION...HAHN
FIRE WEATHER...HAMMER








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