Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 311116
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
516 AM MDT FRI JUL 31 2015

.SHORT TERM...(TODAY AND SUNDAY NIGHT)
ISSUED AT 300 AM MDT FRI JUL 31 2015

TODAY...FLOW ALOFT IS NORTHWEST. INCREASED LOW LEVEL MOISTURE FROM
24 HOURS AGO. DECENT 850/700 MB THETA-E RIDGE AXIS ACROSS SOUTHEAST
WYOMING WITH LOW LEVEL POSITIVE THETA-E ADVECTION...THUS AGREE WITH
THE NAM DEPICTION OF ISOLATED AFTERNOON THUNDERSTORMS ALONG AND EAST
OF INTERSTATE 25.

TONIGHT...THUNDERSTORMS WILL DIE OFF WITH LOSS OF DAYTIME HEATING IN
THE ABSENCE OF UPPER LEVEL ENERGY.

SATURDAY...LOW AND MID LEVEL WINDS SWITCH TO A NORTH DIRECTION WITH
DRIER AND MORE STABLE AIRMASS IN PLACE...THOUGH STILL ENOUGH
INSTABILITY FOR A SLIGHT CHANCE OF AFTERNOON THUNDERSTORMS MAINLY
ACROSS WESTERN NEBRASKA.

SATURDAY NIGHT/SUNDAY/SUNDAY NIGHT...FLOW ALOFT REMAINS NORTHWEST.
LOW AND MID LEVEL THETA-E RIDGE AXIS WILL LIE JUST SOUTH OF THE
COLORADO STATE LINE AND THERE WILL BE ENOUGH POSITIVE THETA-E
ADVECTION FOR ISOLATED THUNDERSTORMS JUST NORTH OF THE STATE LINE IN
THE AFTERNOON...THEN STORMS ENDING IN THE EVENING WITH LOSS OF
DAYTIME HEATING.

.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 300 AM MDT FRI JUL 31 2015

RIDGE AXIS STILL FORECAST TO DRIFT OFF TO THE EAST OF THE CHEYENNE
CWFA MONDAY ALLOWING MONSOONAL MOISTURE TO DRIFT NORTH INTO THE
AREA. SHORTWAVE ENERGY MONDAY NIGHT INTO TUESDAY MORNING MOVES
THROUGH THE AREA. BOTH THE GFS AND ECMWF SHOW THIS HAPPENING.
ECMWF MORE BULLISH ON QPF WHILE GFS KEEP MOST RAINFALL SOUTH IN
COLORADO. FOLLOWED THE ECMWF SOLUTION IN OUR FORECAST AND RAISED
POPS OVER GUIDANCE MONDAY AFTERNOON AND EVENING.

NEED TO BE WATCHING TUESDAY AND WEDNESDAY AS WE COULD BE LOOKING
AT SEVERE THUNDERSTORMS. HAVE A 60KT JET MOVING OVER THE AREA THAT
WILL INTERACT WITH A STALLED OUT FRONTAL BOUNDARY EAST OF THE
LARAMIE RANGE. GFS HAS JET FURTHER NORTH THAN THE ECMWF. WEATHER
DEFINITELY MORE UNSETTLED THROUGH MUCH OF NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 513 AM MDT FRI JUL 31 2015

HRRR USED FOR TIMING OF CONVECTION ALONG THE I-80 CORRIDOR THIS
AFTERNOON. HAS CONVECTION DEVELOPING ACROSS THE SOUTH LARAMIE
RANGE AND NORTHERN COLORADO...DRIFTING NORTHEAST INTO THE PLAINS
AFTER 22Z OR SO. CONTINUED VCTS WORDING FOR KCYS...KLAR AND KSNY.

&&

.FIRE WEATHER...
ISSUED AT 152 AM MDT FRI JUL 31 2015

LOW AFTERNOON RELATIVE HUMIDITIES AGAIN IN THE
AFTERNOON WEST OF INTERSTATE 25 THE NEXT FEW DAYS...THOUGH
FORTUNATELY WINDS WILL BE RELATIVELY LIGHT.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RUBIN
LONG TERM...GCC
AVIATION...GCC
FIRE WEATHER...RUBIN


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