Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 311735
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1135 AM MDT TUE MAR 31 2015

.SHORT TERM...(TODAY THROUGH THURSDAY NIGHT)
ISSUED AT 312 AM MDT TUE MAR 31 2015

CLEAR SKIES AND LIGHT WINDS THIS MORNING WILL GIVE WAY TO SLOWLY
INCREASING HIGH CLOUDS AND GUSTY WINDS THIS AFTERNOON. AN UPPER
LEVEL RIDGE AXIS WILL BE OVER THE FORECAST AREA TODAY BUT WILL BE
REPLACED BY A TROUGH WHICH WILL SHIFT INTO THE ROCKIES TONIGHT AND
WEDNESDAY. MILD TEMPERATURES TODAY WILL BE REPLACED WITH COOLER
AIR WEDNESDAY AS A SHORT WAVE NEAR THE CANADA US BORDER DRIVES A
COLD FRONT SOUTHWARDS INTO THE NORTHERN AND CENTRAL ROCKIES.

THE OVERALL WEATHER PATTERN BECOMES A BIT MESSY WEDNESDAY NIGHT
INTO THURSDAY AS THE NORTHERN AND SOUTHERN STREAMS BRIEFLY
INTERACT OVER THE FORECAST AREA. THE MAIN FORECAST QUESTION IS HOW
EXACTLY WILL THE NORTHERN STREAM COLD FRONT IMPACT AND INTERACT
WITH THE UPPER LEVEL SOUTHERN STREAM ENERGY. LOOKING AT MODEL
TRENDS OVER THE LAST SEVERAL WEEKS...MODEL BIASES HAVE BEEN TOO
FAR NORTH WITH THE PLACEMENT OF SOUTHERN STEAM UPPER LEVEL
ENERGY IN THE DAY LEADING UP TO THE PASSAGE OF UPPER LEVEL ENERGY.
NOT SAYING THAT WILL BE THE CASE THIS TIME BUT SEEMS HIGHLY
PROBABLE...ESPECIALLY WITH BOTH THE LATEST 00Z GFS AND ECMWF
MODELS RUNS TRENDING A BIT DRIER ACROSS THE FORECAST AREA THAN
THE PREVIOUS RUNS.

WILL HAVE TO KEEP A CLOSE EYE ON THIS SYSTEM ESPECIALLY FOR
THURSDAY AS THAT IS WHEN THE MAIN POTENTIAL FOR SNOW ACCUMULATIONS
LOOKS TO BE AT THIS TIME. OF COURSE MOST SNOW WILL MELT THIS TIME
OF YEAR DURING THE DAYTIME HOURS ASSUMING SNOW RATES ARE NOT TOO
HIGH. BASED ON LATEST MODEL OUTPUT...SHOULD SNOW OCCUR MOST OF IT
WOULD MELT SO NOT EXPECTING MUCH IMPACT TO TRAVEL AT THIS TIME.
WITH THE UPPER LEVEL JET EXPECTED TO BE OVER SOUTHERN COLORADO
THURSDAY...THE CHANCES FOR SNOW ACCUMULATIONS LOOKS TO BE LOW WITH
THE MAIN POTENTIAL NEAR THE WYOMING AND COLORADO BORDER.

.LONG TERM...(FRIDAY THROUGH MONDAY)
ISSUED AT 312 AM MDT TUE MAR 31 2015

LINGERING LIGHT SNOW OVER MAINLY THE SOUTHERN PART OF THE CWA SHOULD
BREAK UP INTO MORE ISOLATED RAIN AND SNOW SHOWERS FRIDAY MORNING
AS AN UPPER SHORTWAVE EXITS EAST OF THE CWA. TEMPS WILL ALSO
REBOUND SOME AS THE COOL SFC HIGH SETTLES DOWN INTO THE SOUTHERN
PLAINS AND RETURN FLOW SETS UP OVER THE CWA. DRY AND MILD WEATHER
EXPECTED OVER THE WEEKEND AS A LOW-AMPLITUDE UPPER RIDGE MOVES
ACROSS THE REGION. WINDS SHOULD INCREASE A BIT ON SUNDAY AS WSW
UPPER FLOW DEVELOPS AND LEE TROUGHING DEEPENS OVER THE HIGH
PLAINS. CONTINUED MAINLY DRY ON MONDAY BUT A LITTLE COOLER OVER
THE PLAINS BEHIND A COOL FRONT THAT LOOKS TO PASS ACROSS MONDAY
MORNING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1127 AM MDT TUE MAR 31 2015

THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE TIMING OF THE
BOUNDARY MOVING THROUGH WEDNESDAY MORNING.

LATEST SATELLITE LOOP WAS SHOWING MAINLY CLEAR SKIES WITH FAIRLY
LIGHT WIND SPEEDS. THE WIND SPEEDS SHOULD GRADUALLY INCREASE THIS
AFTERNOON AS THE BOUNDARY LAYER BEGINS TO MIX. OTHERWISE...A SURFACE
FRONT WILL PUSH THROUGH THE NORTHERN PORTION OF THE FORECAST AREA
AFTER 12Z. THIS WILL PRIMARILY IMPACT THE CDR TAF SITE THE
EARLIEST WITH SNY BEING THE LATEST AROUND 16Z OR SO. NO PRECIPATION
IS EXPECTED AS THIS BOUNDARY PASSES THROUGH.



&&

.FIRE WEATHER...
ISSUED AT 312 AM MDT TUE MAR 31 2015

RED FLAG WARNINGS ARE IN PLACE TO DAY FOR THE NEBRASKA PANHANDLE
AND PORTIONS OF SOUTHEAST WYOMING. THE STRONGEST WINDS WILL BE
FOUND OVER SOUTHEAST WYOMING WHERE GUSTS OF 30 TO 35 MPH WILL BE
COMMON THIS AFTERNOON. CRITICAL CONDITIONS ARE MUCH MORE MARGINAL
INTO THE NEBRASKA PANHANDLE WHERE GUSTS ARE GENERALLY EXPECTED TO
BE AROUND 25 MPH WITH AFTERNOON. MAY NOT ACTUALLY SEE WIND GUSTS
TO 25 MPH NEAR THE INTERSTATE 80 CORRIDOR IN THE SOUTHERN NEBRASKA
PANHANDLE BUT GIVEN HUMIDITY VALUES NEAR 10 PERCENT...DECIDED NOT
TO SPLIT HAIRS ON WIND SPEEDS...ESPECIALLY WITH WFO NORTH PLATE
PLACING ZONE 204 INTO A RED FLAG WARNING.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR WYZ310.

     RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR WYZ301-302-306.

NE...RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR NEZ311>313.

&&

$$

SHORT TERM...SML
LONG TERM...RE
AVIATION...REC
FIRE WEATHER...SML



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