Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 280551
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1151 PM MDT SUN JUL 27 2014

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 330 PM MDT SUN JUL 27 2014

THE AFTERNOON WATER VAPOR LOOP REVEALED TWO FEATURES: A POTENT
SHORTWAVE TROUGH AFFECTING THE GREAT LAKES AND OH VALLEY...AND
A UPPER RIDGE FROM THE SOUTHERN GREAT PLAINS TO THE PACIFIC
NORTHWEST. ABUNDANT SUBTROPICAL MOISTURE WAS SPREADING NORTH AND
EAST UNDER THE RIDGE THROUGH THE CENTRAL/SOUTHERN ROCKIES AND
DESERT SOUTHWEST. INSTABILITY FROM DAYTIME HEATING RESULTED IN
A GOOD COVERAGE OF CONVECTION ACROSS CENTRAL/SOUTHERN COLORADO.
MORE ISOLATED SHOWERS/STORMS WERE FORMING OVER THE NORTHERN
COLORADO FRONT RANGE INTO FAR SOUTHERN WYOMING MOUNTAINS. FOR THE
REMAINDER OF THE AFTERNOON...TSTORM COVERAGE WILL BE ISOLATED
OVER THE SOUTHEAST WYOMING FRONT RANGE AND POSSIBLY AS FAR EAST
AS CHEYENNE. WEAK SHEAR AND SBCAPES BELOW 1000 J/KG SHOULD
PRECLUDE SEVERE THREAT. THE CONVECTION WILL LINGER THROUGH EARLY
EVENING THEN DISSIPATE WITH LOSS OF DAYTIME HEATING.

THE SHORT RANGE MODEL GUIDANCE IS IN GOOD AGREEMENT PROGGING THE
UPPER RIDGE AXIS TO BUILD WHILE HOLDING NEARLY STATIONARY OVER
THE INTERMOUNTAIN WEST THROUGH THE PERIOD. WITH THE CWA DOWNSTREAM
OF THE RIDGE...NORTHWEST FLOW ALOFT WILL PREVAIL. SHOWER/TSTORM
COVERAGE WILL BEGIN TO INCREASE MONDAY AFTERNOON OVER THE SOUTHERN
CWA AS SUBTROPICAL PLUME SHIFTS NORTH FROM COLORADO. WHILE THE
MAJORITY OF THE CONVECTION WILL BE DIURNALLY DRIVEN...CANNOT RULE
OUT AT LEAST ISOLATED COVERAGE MONDAY NIGHT. TUESDAY WILL BEGIN
A 24 TO 48 PERIOD OF MORE WIDESPREAD CONVECTION AS DEEPER SUBTROPICAL
MOISTURE AFFECTS THE REGION. THE MAJORITY OF THE MODELS DEPICT
PRECIP WATER VALUES IN THE 1.0-1.5 INCH RANGE TUESDAY AFTERNOON/EVENING.
SBCAPES PEAK BETWEEN 400 AND 800 J/KG WITH WEAK SHEAR PROFILES
LIMITING THE SEVERE POTENTIAL. MAIN CONCERN WILL BE HEAVY RAINFALL
WHICH MAY PRODUCE MINOR FLOODING. 6-HOURLY QPF CONSENSUS PROGS ONE
TO TWO INCHES OF RAINFALL BETWEEN 18Z TUESDAY AND 12Z WEDNESDAY
OVER MUCH OF SOUTH CENTRAL AND SOUTHEAST WYOMING.

LOW TEMPERATURES TONIGHT WILL BE MOSTLY IN THE 40S AND 50S WITH
LIMITED CLOUD COVER. MONDAY AND TUESDAY NIGHTS WILL BE MILDER WITH
MORE LOW LEVEL MOISTURE IN PLACE RESULTING IN LOWS MOSTLY IN THE
50S TO LOWER 60S. MONDAY WILL BE A SEASONABLY WARM DAY WITH HIGHS
IN THE 70S AND 80S WITH 60S OVER THE MOUNTAINS. GREATER CLOUD
AND SHOWER COVERAGE WILL KEEP HIGH TEMPERATURES 5-10 DEGREES
COOLER THAN MONDAY ESPECIALLY ALONG AND WEST OF THE LARAMIE RANGE.
A LOOSE PRESSURE GRADIENT AND WEAK WINDS ALOFT WILL KEEP SUSTAINED
SURFACE WINDS 15 KT OR LESS DURING THE PERIOD. THE EXCEPTION WILL
BE IN AND NEAR SHOWER/TSTORM ACTIVITY WITH ERRATIC AND GUSTY WINDS.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 230 PM MDT SUN JUL 27 2014

MILD TEMPERATURES EXPECTED WEDNESDAY ESPECIALLY OVER SE WYOMING
WHERE CLOUDS AND UPSLOPE-INDUCED PCPN WILL KEEP TEMPS DOWN...NOT
EVEN REACHING THE 70S OVER THE HIGH PLAINS. NW FLOW ALOFT WILL BE
OVER THE AREA WITH IMPULSES RIDING SE ACROSS THE AREA AND
INTERACTING WITH GOOD MOISTURE AVAILABILITY BANKED UP AGAINST THE
MTNS. MOISTURE WILL BEGIN BEING SUPPRESSED SOUTH ON THURSDAY AND
FRIDAY THUS EXPECT CONVECTIVE ACTIVITY TO FALL OFF TO A MORE
ISOLATED BASIS. GENERALLY DRY WEATHER FOR SATURDAY AND SUNDAY
THOUGH SOME CONVECTION STILL POSSIBLE OVER THE MTNS. TEMPS WILL
WARM SLOWLY LATE IN THE WEEK AND WEEKEND BUT STILL BE AT OR EVEN A
BIT BELOW SEASONAL AVERAGES PARTICULARLY OVER THE PLAINS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY EVENING)
ISSUED AT 1129 PM MDT SUN JUL 27 2014

GENERALLY VFR ACROSS THE AREA TONIGHT BUT COULD SEE SOME LOW CIGS
AND FOG NEAR THE LARAMIE RANGE TOWARDS SUNRISE MONDAY. ANY FOG OR
LOW CLOUDS WOULD QUICKLY LIFT AFTER SUNRISE. SCATTERED SHOWERS AND
THUNDERSTORMS WILL DEVELOP ALONG AND WEST OF THE SOUTHERN LARAMIE
RANGE MONDAY AFTERNOON. HEAVY RAIN MAY PRODUCE LOW VISIBILITIES
WITH SOME OF THE SHOWERS AND THUNDERSTORMS. SHOWER AND
THUNDERSTORMS ACTIVITY WILL LINGER LATE INTO MONDAY NIGHT.

&&

.FIRE WEATHER...
ISSUED AT 213 PM MDT SUN JUL 27 2014

RELATIVE HUMIDITIES WILL INCREASE THROUGH MID WEEK WITH A PREVAILING
MOIST SOUTHERLY FLOW. MODEST UPSLOPE WINDS AND WEAK DISTURBANCES
ALOFT WILL RESULT IN GREATER CHANCES OF SHOWERS AND THUNDERSTORMS...
ESPECIALLY TUESDAY AND WEDNESDAY WHEN THE POTENTIAL FOR HEAVY
RAINFALL WILL EXIST. BELOW AVERAGE TEMPERATURES ARE EXPECTED. SHOWER
CHANCES WILL DECREASE AND TEMPERATURES WILL WARM LATER IN THE WEEK
AND NEXT WEEKEND.

&&

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

$$

SHORT TERM...JAMSKI
LONG TERM...EMANUEL
AVIATION...SML
FIRE WEATHER...JAMSKI






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