Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 230235
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
835 PM MDT FRI APR 22 2016

.UPDATE...
ISSUED AT 831 PM MDT FRI APR 22 2016

WENT AHEAD WITH A HIGH WIND WATCH FOR THE WIND PRONE AREAS OF
SOUTHEAST WYOMING. WANTED TO GET IT OUT FOR THE 10 PM BROADCAST AS
WELL AS HELPING OUT THE MID SHIFT. 700MB WINDS STILL RANGE FROM
55-65KTS ON GFS. THIS WATCH MAY NEED EXPANDED EVENTUALLY AS MAV
MOS SPEEDS AT RAWLINS UP TO 44KTS BY TOMORROW NIGHT. A WATCH FOR
THE WIND PRONE AREAS SOUNDED LIKE A GOOD BET. UPDATES HAVE BEEN
SENT.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 203 PM MDT FRI APR 22 2016

HIGH AMPLITUDE UPPER-LEVEL RIDGING HAS CONTRIBUTED TO AMPLE SUNSHINE
AND VERY WARM/DRY CONDITIONS ACROSS THE AREA TODAY. NO MAJOR WEATHER
CONCERNS THROUGH TONIGHT WITH LIMITED MOISTURE AND STRONG SUBSIDENCE
OVER THE CWA. AFTERNOON WATER VAPOR SATELLITE IMAGERY SHOWS A STRONG
UPPER LOW SPINNING OFF COAST OF NORTHERN CA/OR. SOUTHWEST FLOW ALOFT
IN ADVANCE OF THIS FEATURE WILL YIELD INCREASING 700-300 MB MOISTURE
ON SATURDAY. THIS COMBINED WITH DIFLUENT FLOW ALOFT AND A 70-80 KNOT
JETLET OVER NORTHERN CO SHOULD ALLOW SHOWERS TO DEVELOP FROM WEST TO
EAST THROUGH THE DAY. BUFKIT SOUNDINGS CONTINUE TO SHOW BETWEEN 250-
500 J/KG CAPE...SO MAINTAINED MENTION OF THUNDER AFTER 18Z. GOING TO
NEED TO WATCH THE LOWER ELEVATIONS OF CARBON COUNTY WITH MAV AND MET
GUIDANCE BOTH SHOWING 30 KT SUSTAINED WINDS AND 50+ KNOT FLOW AT THE
TOP OF THE MIXED LAYER. FULLY EXPECT CLOUD COVER TO LIMIT MIXING BUT
ANY CONVECTION COULD DEFINITELY YIELD DOWNWARD MOMENTUM TRANSFER. AM
NOT CONFIDENT ENOUGH ATTM TO ISSUE A HIGH WIND WATCH.

THE AFOREMENTIONED WAVE WILL MOVE QUICKLY EASTWARD ON SATURDAY W/THE
COLD FROPA OCCURRING SATURDAY NIGHT. A HIGH WIND EVENT STILL APPEARS
LIKELY FOR THE WIND CORRIDORS AFTER 00Z WITH AN H85 CAG-CPR GRADIENT
BETWEEN 65 AND 75 METERS AND 700 MILLIBAR FLOW OF 50-60 KNOTS. MODEL
TRENDS HAVE BEEN FOR LOWER WIND SPEEDS ALOFT...SO FOR THAT REASON WE
DECIDED NOT TO ISSUE A HIGH WIND WATCH ATTM. OUR LOCAL PROBABILISTIC
MODEL FOR BRX BASED ON GFS OUTPUT SHOWED A 90 PERCENT PROBABILITY OF
EXCEEDANCE ON EARLIER RUNS...BUT HAS SINCE FALLEN TO 30 PERCENT AT A
FORECAST HOUR OF 12Z SUNDAY. MODELS ARE IN GOOD AGREEMENT WITH STEEP
LOW-LEVEL LAPSE RATES THROUGH SUNDAY AFTERNOON...WITH WIDESPREAD 40+
KT FLOW ALOFT. SUNDAY WILL BE A VERY WINDY DAY OVER ALL OF SOUTHEAST
WYO AND THE WESTERN NEB PANHANDLE WITH SCATTERED TO NUMEROUS SHOWERS
WITH INSTABILITY BENEATH THE UPPER LOW. SIGNIFICANT PRECIPITATION IS
UNLIKELY THROUGH SUNDAY AFTERNOON. H7 TEMPS SHOULD BE COLD ENOUGH TO
SUPPORT MOUNTAIN SNOW...SO COULD SEE SEVERAL INCHES IN THE SNOWY AND
SIERRA MADRES APPROACHING ADVISORY CRITERIA THIS WEEKEND.

.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 203 PM MDT FRI APR 22 2016

THE MODELS ARE IN AGREEMENT AT SHOWING A RATHER ACTIVE EXTENDED
PERIOD. MONDAY WILL LIKELY BE THE WARMEST DAY...BUT EVEN THEN
TEMPS WILL ONLY BE IN THE 50S TO LOW 60S ACROSS THE REGION. LLVL
SOUTHEASTERLY WINDS WILL TRANSPORT MOISTURE WESTWARD ACROSS THE
PLAINS ON MONDAY. THE MODELS SHOW A CLOSED UPPER LOW OVER UTAH ON
MONDAY NIGHT WITH LARGE SCALE ASCENT AND UPPER LEVEL DIVERGENCE
INCREASING OVER THE CWA. HAVE WIDESPREAD POPS IN THE 50-70
PERCENT RANGE ON MONDAY NIGHT INTO TUESDAY...HIGHEST TO THE EAST
OF THE LARAMIE RANGE. AT THIS TIME IT LOOKS LIKE MUCH OF THE
PRECIP WILL FALL AS RAIN OVER LOWER ELEVATIONS...HOWEVER WILL HAVE
TO WATCH THE UPPER LOW TRACK (AND ASSOCIATED LLVL COLD AIR
ADVECTION) AS IT EJECTS EASTWARD ON TUES NIGHT. PRECIP CHANCES
WILL BE ON THE DECREASE THE LAST HALF OF WED WITH COOL TEMPS
PERSISTING THROUGH THURS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 554 PM MDT FRI APR 22 2016

VFR CONDITIONS WITH SOUTHWEST WINDS INCREASING SATURDAY ACROSS
SOUTHEAST WYOMING AIRPORTS. STRONG WINDS PERSISTING INTO SUNDAY.


&&

.FIRE WEATHER...
ISSUED AT 203 PM MDT FRI APR 22 2016

ELEVATED FIRE WEATHER CONDITIONS ARE POSSIBLE FROM LATE THIS AFTN
THROUGH SATURDAY WITH HUMIDITY VALUES BELOW 20 PERCENT. WINDS ARE
EXPECTED TO BE UNDER CRITICAL THRESHOLDS THROUGH THIS EVENING BUT
WILL INCREASE BY MIDDAY SATURDAY WITH GUSTS BETWEEN 35 AND 45 MPH
ACROSS CARBON COUNTY. WIND GUSTS BETWEEN 25 AND 35 MPH ARE LIKELY
ELSEWHERE. COOLER AND UNSETTLED WEATHER WILL ARRIVE ON SUNDAY AND
CONTINUE INTO NEXT WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...HIGH WIND WATCH FROM SATURDAY EVENING THROUGH SUNDAY AFTERNOON
     FOR WYZ106-110-116-117.

NE...NONE.
&&

$$

UPDATE...GCC
SHORT TERM...CLH
LONG TERM...ZF
AVIATION...GCC
FIRE WEATHER...CLH



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