Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 300530
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1130 PM MDT SUN MAR 29 2015

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 215 PM MDT SUN MAR 29 2015

WINDS ARE DECREASING ACROSS THE NEBRASKA PANHANDLE THIS AFTN AS
THE GRADIENT RELAXES. RH VALUES HAVE DROPPED TO AROUND 15
PERCENT...HOWEVER DO NOT SEE WINDS INCREASING THROUGH THE
REMAINDER OF THE AFTN TO WARRANT RED FLAG WARNINGS. THE WEATHER
WILL BE RATHER QUIET THROUGH TUES WITH WARM TEMPS AND POTENTIAL
CRITICAL FIRE WEATHER CONDITIONS BEING THE MAIN ISSUES. WITH THE
MIDLVL RIDGE AXIS CENTERED OVER UTAH ON MON...NORTHWESTERLY FLOW
ALOFT WILL OCCUR ACROSS THE CWA. THE AIRMASS WILL BE VERY DRY ONCE
AGAIN...AND LOWERED DEWPOINTS AND RH VALUES MORE IN LINE WITH THE
DRIER GFS. THE NAM HAS CONSISTENTLY BEEN TOO MOIST WHEN THERE IS
DEEP MIXING...AND CLEAR SKIES AND A DEEP BOUNDARY LAYER WILL BE IN
PLACE ON MON AFTN. THE GFS SHOWS 25 KTS AT THE TOP OF THE MIXED
LAYER IN AREAS ALONG INTERSTATE 80 ACROSS SOUTHEAST WYOMING.
THUS...WITH MIN RH VALUES OF 12-15 PERCENT AND GUSTS TO 25-30
MPH...DECIDED TO ISSUE A FIRE WEATHER WATCH FOR ZONE 310. THIS IS
A MARGINAL EVENT...DEFINITELY NOT LIKE THE EXTREMELY CRITICAL
CONDITIONS WE SAW ON SAT.

SHORTWAVE RIDGE AXIS WILL MOVE OVERHEAD ON TUES WITH PRESSURE
FALLS OCCURRING DURING THE AFTN AND EVENING ACROSS NORTHEAST WY.
700MB TEMPS RISE TO AROUND 7C WITH WIDESPREAD HIGHS IN THE 70S TO
THE EAST OF THE LARAMIE RANGE SO IT WILL BE ABOUT 5 DEGREES WARMER
THAN MON. THE QUESTION ON TUES IS WHETHER WINDS WILL BE HIGH
ENOUGH TO THE EAST OF THE LARAMIE RANGE (WHERE FUELS ARE READY) TO
SUPPORT RED FLAG CONDITIONS. THERE WILL BE DEEP MIXING SO COULD
SEE SOME GUSTS TO 20 KTS...AND NEAR CRITICAL FIRE WEATHER
CONDITIONS WILL EXIST ONCE MORE. SOUNDINGS AND LI VALUES AROUND 0C
SUGGEST THAT SCATTERED HIGH BASED CUMULUS WILL BE PRESENT DURING
THE AFTN.

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 215 PM MDT SUN MAR 29 2015

A WARM DAY WEDNESDAY AS TRANSITORY RIDGE MOVES THROUGH THE AREA.
700MB WINDS INCREASE TO 35-40KTS WITH AFTERNOON HIGHS IN THE 60S
AND LOW 70S. PROBABLY OUR BEST CHANCE FOR CRITICAL FIRE WEATHER
CONDITIONS LATE WEDNESDAY MORNING INTO THE AFTERNOON.

GFS AND ECMWF CONTINUE TO STRUGGLE ON WHAT IS GOING TO HAPPEN FROM
WEDNESDAY NIGHT ON INTO THE END OF THE WEEK. GFS DRIVES A FRONTAL
BOUNDARY THROUGH WYOMING INTO NORTHERN COLORADO WEDNESDAY EVENING
THAT STALLS OVER NORTHERN COLORADO. ECMWF CONTINUES TO MOVE THIS
BOUNDARY FURTHER SOUTH AND EAST. BY THURSDAY AFTERNOON...GFS
BRINGS ANOTHER UPPER SHORTWAVE INTO SOUTHERN WYOMING THAT LIFTS
THE FRONT NORTH INTO THE INTERSTATE 80 CORRIDOR AND STALLS IT
THERE THROUGH FRIDAY. ECMWF DRIVES THE UPPER SHORTWAVE ACROSS
SOUTHERN AND CENTRAL COLORADO WITH MOST MOISTURE STAYING SOUTH OF
OUR CWFA.

TRENDING TOWARDS THE GFS SOLUTIONS AS IT HAS BEEN THE MOST
CONSISTENT OVER THE PAST SEVERAL DAYS. SHOULD THIS SOLUTION COME
TRUE...WE ARE LOOKING AT A PRETTY WIDESPREAD SNOW EVENT THURSDAY
EVENING INTO FRIDAY. INCREASED POPS ACROSS THE AREA FOR THIS
TIMEFRAME. 700MB TEMPERATURES OF 10 TO -11C SHOULD BE COLD ENOUGH
FOR MOST OF THIS PRECIPITATION TO FALL AS SNOW...AT LEAST FOR
SOUTHEAST WYOMING. PANHANDLE MAY SEE MORE OF A RAIN/SNOW MIX
DEPENDING ON TIME OF DAY.

GOOD NEWS WITH THIS EVENT SHOULD IT COME TRUE...ABUNDANT QPF
SHOULD KICK START THE GREEN UP PROCESS AND PUT A DAMPER ON FIRE
WEATHER CONCERNS FOR THE SPRING.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1129 PM MDT SUN MAR 29 2015

VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. GUSTY WINDS ARE
EXPECTED OVER SOUTHEAST WYOMING TERMINALS ON MONDAY AFTERNOON.

&&

.FIRE WEATHER...
ISSUED AT 215 PM MDT SUN MAR 29 2015

THE DRY CONDITIONS WILL CONTINUE THROUGH WEDNESDAY WITH
PRECIPITATION CHANCES RETURNING TO THE DISTRICT ON THURSDAY.  A
FIRE WEATHER WATCH HAS BEEN ISSUED FOR FIRE WEATHER ZONE 310 FOR
MONDAY AFTERNOON.  MINIMUM AFTERNOON HUMIDITY VALUES WILL DROP TO
12-15 PERCENT AND WIND GUSTS TO 25-30 MPH WILL BE POSSIBLE.  EVEN
WARMER TEMPERATURES WILL OCCUR ON TUESDAY.  TUESDAY AND WEDNESDAY
WILL SEE ELEVATED TO NEAR CRITICAL FIRE WEATHER CONDITIONS...MAINLY
ACROSS SOUTHEAST WYOMING.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...FIRE WEATHER WATCH FROM 10 AM MDT MONDAY THROUGH MONDAY EVENING
     FOR WYZ310.

NE...NONE.
&&

$$

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


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