Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 281132
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
532 AM MDT SUN JUN 28 2015

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 342 AM MDT SUN JUN 28 2015

A LINE OF SHOWERS AND THUNDERSTORMS HAVE DEVELOPED EARLY THIS
MORNING DOWNSTREAM OF THE BIG HORNS ON THE NOSE OF THE UPPER LEVEL
JET. ADDED IN ISOLATED THUNDER ALONG THIS LINE WHICH STRETCHES
SOUTHEAST ACROSS EASTERN CONVERSE COUNTY...ALTHOUGH IT APPEARS THIS
CONVECTION IS STRUGGLING TO MAINTAIN AS IT CROSSES THE COUNTY LINE.
OTHERWISE...DRY CONDITIONS PREVAIL ELSEWHERE WITH LIGHT WINDS IN
PLACE. THE 70 KT NW JET WILL MOVE OVERHEAD TODAY ALONG WITH
CONTINUED MID/UPPER LEVEL MOISTURE AND WEAK MIDLEVEL ENERGY ON THE
EASTERN PERIPHERY OF A HIGH AMPLITUDE RIDGE SITUATED OVER THE
WESTERN CONUS. AT THE SFC...WINDS WILL GENERALLY BE OUT OF THE NORTH
TO NORTHEAST DURING PEAK HEATING WITH CONVERGENCE SETTING UP ALONG
THE LARAMIE RANGE AND CHEYENNE RIDGE. MODELS ARE PAINTING SBCAPE
VALUES ANYWHERE FROM 500 TO 1500 J/KG ALONG AND WEST OF I-25 BY THE
AFTERNOON...WITH LESS INSTABILITY FURTHER EAST ACROSS THE PLAINS IN
THIS PATTERN. SO MAINTAINED CHANCE POPS FOR SHOWERS/ISO-T WITHIN THE
HIGHER AREAS OF INSTABILITY OVER THE MOUNTAINS...AND SLIGHT CHANCE
FOR NEARBY LOCATIONS. BULK SHEAR VALUES ARE ON THE ORDER OF 30-40
KTS SO WOULD NOT BE SURPRISED TO SEE GUSTY WINDS AND SMALL HAIL
ALONG WITH MODERATE RAINFALL IN SOME STORMS THAT TAP INTO THE HIGHER
INSTABILITY. THIS ACTIVITY SHOULD WANE QUICKLY WITH SUNSET ALTHOUGH
WITH THE JET STILL OVERHEAD...MAY SEE A STRAY SHOWER OR TWO
OVERNIGHT.

FOR MONDAY...THE UPPER HIGH CENTER STILL LOOKS LIKE IT WILL PUSH
BACK EAST A BIT...BRINGING DRIER AIR AND STRONGER SUBSIDENCE TO THE
FORECAST AREA. OUTSIDE OF A FEW MOUNTAIN SHOWERS/STORMS...EXPECT DRY
AND VERY WARM CONDITIONS TO PREVAIL. THE RIDGE WILL BEGIN TO BREAK
DOWN ON TUESDAY AS STRONGER SHORTWAVE ENERGY RIDES ATOP THE RIDGE
ALONG THE US/CANADIAN BORDER...AND DOWN INTO THE GREAT PLAINS.
INCREASING MIDLEVEL ENERGY ALONG WITH A DEVELOPING LEESIDE SFC
PRESSURE TROUGH WILL ALLOW FOR SOUTHEASTERLY SFC WINDS TO INCREASE
THROUGH THE DAY ACROSS THE PLAINS...ALONG WITH LLVL MOISTURE
ADVECTION. WITH STRENGTHENING SFC CONVERGENCE AND INCREASING
MIDLEVEL PACIFIC MOISTURE AS WELL...WILL SEE A BROADER COVERAGE OF
SHOWERS AND THUNDERSTORMS ACROSS THE CWA FOR TUESDAY AFTERNOON. THE
THERMAL RIDGE WILL MOVE OVERHEAD AS THE UPPER RIDGE AXIS SHIFTS
OVERHEAD...SO EXPECT TEMPS TO RISE A FEW DEGREES FROM MONDAY INTO
THE 80S AND 90S.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 342 AM MDT SUN JUN 28 2015

00Z MODEL OUTPUT IS IN AGREEMENT IN RETROGRADING THE GREAT BASIN
UPPER HIGH WEST TO NRN CALIFORNIA THRU THE END OF THE WEEK.
ALTHOUGH NORTHWEST FLOW WILL PREVAIL THRU THE ENTIRE PERIOD...
HEIGHTS WILL GRADUALLY FALL AS THIS UPPER HIGH SHIFTS WEST AND
FLATTENS. A SERIES OF SHORTWAVES EMBEDDED WITHIN THE NORTHWEST
FLOW WILL DIVE SOUTHEAST FROM THE CANADIAN ROCKIES INTO THE HIGH
PLAINS...EACH DRAGGING WEAK SFC BOUNDARIES THRU AREAS EAST OF THE
LARAMIE RANGE. LLVL CONVERGENCE ALONG THESE BOUNDARIES ALONG WITH
SLIGHTLY COOLER MID-LEVELS WILL CONTRIBUTE TO THE NECESSARY
INSTABILITY FOR NEARLY DAILY AFTERNOON/EVENING THUNDERSTORM
CHANCES ESPECIALLY FOR LOCATIONS IN AND AROUND THE SOUTHEAST
WYOMING MOUNTAINS WED-FRI. TEMPERATURES WILL BE SEASONAL THROUGH
THE PERIOD AS H7 TEMPERATURES HOVER BETWEEN 10-15C. HIGH
TEMPERATURES WILL REACH THE 80S THROUGH MOST OF THE PERIOD...
THOUGH SOME 70S CAN BE EXPECTED ABOVE 5000 FEET THU-SAT.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 527 AM MDT SUN JUN 28 2015

VFR CONDITIONS EXPECTED WITH HIGH PRESSURE OVER THE ROCKIES
THROUGH THE NEXT 24-48 HOURS. COULD SEE SOME ISOLATED
THUNDERSTORMS AROUND KCYS THIS AFTERNOON. CONFIDENCE NOT HIGH ON
THIS HAPPENING THOUGH. SO WILL CONTINUE VCTS WORDING IN THE TAF.

&&

.FIRE WEATHER...
ISSUED AT 342 AM MDT SUN JUN 28 2015

NO FIRE WEATHER CONCERNS ARE EXPECTED THROUGH MUCH OF NEXT WEEK FOR
AREAS EAST OF THE LARAMIE RANGE AS DAYTIME HUMIDITIES WILL
RANGE BETWEEN 25 AND 40 PERCENT. WEST OF THE LARAMIE RANGE...FIRE
WEATHER CONCERNS WILL BE LOW AS WETTING RAINS ARE POSSIBLE THIS
AFTERNOON OVER THE MOUNTAINS AND NEARBY VALLEYS WITH INCREASED
CHANCES FOR SHOWERS AND T-STORMS. MONDAY WILL SEE OVERALL DRIER
CONDITIONS...HOWEVER AN ISOLATED STORM REMAINS POSSIBLE IN THE
AFTERNOON OVER THE HIGH PEAKS. THUNDERSTORM AND WETTING RAINFALL
CHANCES GRADUALLY INCREASE TUESDAY THROUGH FRIDAY ACROSS THE
REGION.

&&

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

$$

SHORT TERM...RJM
LONG TERM...CAH
AVIATION...GCC
FIRE WEATHER...RJM


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