Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 270937
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
337 AM MDT FRI MAR 27 2015

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 337 AM MDT FRI MAR 27 2015

MOIST NORTHWEST FLOW ALOFT REMAINS IN PLACE ACROSS EASTERN PORTIONS
OF THE CWA THIS MORNING. 09Z OBJECTIVE UPPER AIR ANALYSIS REVEALED A
110 KT UPPER JET EXTENDING FROM THE CENTRAL DAKOTAS INTO NEB. WE ARE
STILL SEEING SOME ENHANCEMENT ON INFRARED SAT IMAGERY AND WEAK RADAR
ECHOS ON THE BACK SIDE OF THE JET. BELIEVE MOST OF THIS ACTIVITY IS
NOT EVEN REACHING THE GROUND...BUT A FEW SFC OBS HAVE REPORTED LIGHT
RAIN FROM TIME TO TIME. WILL KEEP LOWER END POPS GOING THROUGH THE
PRE DAWN HOURS...BUT EXPECT PCPN CHANCES TO GRADUALLY DIMINISH OVER
THE NEXT FEW HOURS AS THE MID LEVEL MOISTURE PLUME SHIFTS EAST. NOT
MUCH ELSE TO SPEAK OF IN THE NEAR TERM. WARMING TREND WILL CONTINUE
TODAY AS HIGH-AMPLITUDE RIDGING BECOMES ESTABLISHED OVER THE WESTERN
CONUS. IT WILL BE ANOTHER BREEZY DAY WITH GOOD WEST-TO-EAST PRESSURE
GRADIENTS IN PLACE AND 30 KT FLOW AT H75.

FIRE WEATHER CONCERNS ARE STILL ON TRACK FOR SAT. UPPER-LEVEL RIDGE
AXIS WILL MOVE OVERHEAD WITH THERMAL PROFILES WARMING QUITE RAPIDLY
INTO THE AFTERNOON. MODELS HAVE TRENDED EVEN WARMER WITH H7 TEMPS AT
00Z SUN...WITH THE GFS/NAM/ECM ALL SHOWING 6+ DEG C. THIS COMBINED
WITH DEEP SUBSIDENCE AND STRONG LLVL DOWNSLOPE SUGGESTS NEAR RECORD
HIGHS OVER THE LOWER ELEVATIONS. DEFINITELY KEEPING FORECAST HIGHS A
FEW DEGREES ABOVE GUIDANCE IN THIS PATTERN. ALSO CONTINUED TO TREND
LOWER FOR DEW POINTS ON SAT AFTERNOON AS GUIDANCE IS ALMOST ALWAYS
TOO MOIST IN THESE SCENARIOS. THE H85 CAG-CPR GRADIENT IS PROGGED AT
AROUND 45 METERS WITH A BROAD SWATH OF 30 TO 40 KT H7-H8 FLOW LIKELY
OVER THE CWA AT PEAK HEATING. GFS/NAM BUFKIT SOUNDINGS SHOW A VERY
DEEP BOUNDARY LAYER...SO EXPECT WIDESPREAD GUSTY WINDS. WILL ISSUE A
FIRE WEATHER WATCH FOR SATURDAY AFTN FOR THE HIGH PLAINS OF EASTERN
WY AND THE WESTERN NE PANHANDLE.

THE GFS AND ECMWF HAVE COME INTO SLIGHTLY BETTER AGREEMENT WITH AN
ENERGETIC...BUT FAST-MOVING MID LEVEL SHORTWAVE AND ASSOCIATED WEAK
COLD FROPA ON SAT NIGHT. STILL NOT ENTIRELY SOLD ON PCPN CHANCES AS
NEITHER MODEL SHOWS MUCH FOR QPF. OVERALL 700-300 MILLIBAR MOISTURE
FIELDS ARE LESS THAN IMPRESSIVE AS WELL...SO ANY SHOWER ACTIVITY IS
EXPECTED TO BE ISOLATED. EXPECT HIGHS WILL BE SOME 10 TO 15 DEGREES
COOLER THAN SAT. STILL A FAIRLY MILD DAY THOUGH AS THE COLUMN SHOULD
WARM QUICKLY FOLLOWING THE PASSAGE OF THE WAVE. WINDS WILL NOT BE AS
STRONG AS PREVIOUS DAYS AS LLVL GRADIENTS WEAKEN.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 337 AM MDT FRI MAR 27 2015

NORTHWEST FLOW EARLY IN THE PERIOD WILL BECOME MORE ZONAL BY THE
MIDDLE OF NEXT WEEK...RESULTING IN A GENERALLY A DRY PERIOD. THERE
ARE EARLY INDICATIONS FOR A FAST-MOVING STORM SYSTEM TO BRING A
ROUND OF UNSETTLED CONDITIONS LATE THURSDAY INTO FRIDAY. BEFORE
THAT HAPPENS THOUGH...LLVL THERMAL RIDGE WILL AMPLIFY OVR THE
INTERMOUNTAIN WEST MONDAY AND TUESDAY. HIGH TEMPERATURES WILL BE
WELL ABOVE AVERAGE FOR THIS TIME OF YEAR...WITH 60S AND EVEN SOME
LOW 70S EXPECTED OVR LOWER ELEVATIONS OF THE WRN NEBRASKA
PANHANDLE. WILL NO DOUBT HAVE TO DEAL WITH SOME FIRE WEATHER
CONCERNS...ESPECIALLY ON TUESDAY AS THE DRY/BREEZY PRE-FRONTAL AIR
MASS SUGGESTS AT LEAST THE POSSIBILITY OF FIRE SPREAD. BOTH THE
ECMWF/GFS ACCELERATE SHORTWAVE ENERGY ACROSS NRN WYOMING/SRN
MONTANA LATE TUESDAY/EARLY WEDNESDAY. THE SYSTEMS PASSAGE TO THE
NORTH OF THE CWFA POINT TO PRIMARILY A WIND PRODUCER WITH LIKELY A
BORA WIND EVENT. THERE MAY BE JUST ENOUGH MOISTURE TO SQUEEZE OUT
A FEW HIGH BASED SHOWERS WEST OF THE LARAMIE RANGE TUESDAY
AFTERNOON/EVENING. DRY CONDITIONS RETURN ON WEDNESDAY ALONG WITH
POST-FRONTAL TEMPERATURES THAT WILL RETURN TO THE 50S AND LOW 60S.
THE NEXT COLD FRONT WILL DROP THRU THE AREA DURING THE DAY ON
THURSDAY AS THE NEXT SHORTWAVE DIVES TOWARD THE FOUR CORNERS.
PRECIPITATION CHANCES WILL BE ON THE INCREASE LATE THURSDAY THRU
FRIDAY AS THE COLDER AIR MASS FILTERS IN BEHIND THE FRONT. IF
CURRENT TEMPERATURE PROGS HOLD...THE INITIAL PRECIP WOULD BE
RAIN...WITH A TRANSITION TO SNOW THURSDAY NIGHT AND FRIDAY
MORNING. TEMPERATURES WILL RETURN BACK TO MORE NORMAL VALUES ON
FRIDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 337 AM MDT FRI MAR 27 2015

VFR CONDITIONS WILL CONTINUE THRU THE PERIOD AS BKN050-100 CLOUD
DECK EARLY GRADUALLY LIFTING TO CIRRUS BY LATE THIS AFTERNOON AND
TONIGHT. NORTHWEST WINDS WILL TURN GUSTY 16-02Z TODAY WITH GUSTS
OF 25-30 KNOTS LIKELY.

&&

.FIRE WEATHER...
ISSUED AT 337 AM MDT FRI MAR 27 2015

ELEVATED FIRE WEATHER CONDITIONS WILL EXIST TODAY WITH WARMER TEMPS
AND GUSTY WESTERLY WINDS IN THE AFTERNOON. RAPID FIRE GROWTH COULD
OCCUR IN THIS ENVIRONMENT...BUT MINIMUM RELATIVE HUMIDITY VALUES ARE
EXPECTED TO REMAIN ABOVE CRITICAL THRESHOLDS. THERE IS A GOOD CHANCE
FOR WIDESPREAD RED FLAG CONDITIONS ON SATURDAY AFTERNOON. HUMIDITIES
EAST OF THE LARAMIE RANGE WILL FALL TO BETWEEN 10 AND 15 PERCENT
WITH WIND GUSTS IN EXCESS OF 30 MPH. A FIRE WEATHER WATCH HAS BEEN
ISSUED FOR THOSE AREAS. A COLD FRONT WILL SWEEP ACROSS THE AREA ON
SATURDAY NIGHT. SLIGHTLY COOLER TEMPERATURES SHOULD LIMIT LINGERING
FIRE WEATHER CONCERNS ON SUNDAY.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...FIRE WEATHER WATCH FROM SATURDAY MORNING THROUGH SATURDAY
     EVENING FOR WYZ301-310.

NE...FIRE WEATHER WATCH FROM SATURDAY MORNING THROUGH SATURDAY
     EVENING FOR NEZ311>313.

&&

$$

SHORT TERM...CLH
LONG TERM...CAH
AVIATION...CAH
FIRE WEATHER...CLH



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