Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 212333
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
533 PM MDT MON JUL 21 2014

.SHORT TERM...(TONIGHT THROUGH WEDNESDAY NIGHT)
ISSUED AT 345 PM MDT MON JUL 21 2014

EARLY AFTERNOON SATELLITE PIX SHOW A FAIRLY WIDESPREAD CU FIELD
DEVELOPING ACROSS THE ENTIRE AREA. VISUALLY...MOST OF THIS ACTIVITY
HAS BEEN SHALLOW...BUT A FEW HAVE RECENTLY HAVE REACH DEPTHS RETURN
ECHOES OFF OF KCYS 88D. MOST OF THE ORGANIZED CONVECTIVE ACTIVITY
THUS FAR HAS BEEN OVR WRN AND CENTRAL WYOMING WHICH IS IN CLOSER
PROXIMITY TO THE PRIMARY SHORTWAVE. PROGD SOUNDINGS ARE SOMEWHAT
UNSTABLE WITH SBCAPES OF 400-700 J/KG. THE DRY SUB-CLOUD LAYER AND
INVERTED-V SOUNDINGS WILL BE A LIMITING FACTOR IN CONVECTIVE
COVERAGE AND STRENGTH. EVEN SO...HAVE INCLUDED SOME SMALL CHANCES
FOR SHOWERS AND A FEW WEAK THUNDERSTORMS EAST OF THE LARAMIE RANGE
THIS EVENING. DO NOT ANTICIPATE MUCH IN THE WAY OF RAINFALL WITH
THIS ACTIVITY...HOWEVER WIND GUSTS TO 40 MPH WILL BE POSSIBLE AS
EVAPORATIVE COOLING OCCURS BENEATH CLOUD-BASE. CONVECTION WILL BE
HEAVILY TIED TO INSOLATION...SO EXPECT QUICK DISSIPATION WITH
SUNSET. HIGH PRESSURE WILL BUILD NORTH INTO THE REGION ON TUESDAY.
WARMER MID-LEVEL TEMPERATURES ASSOCIATED WITH THIS FTR WILL
EFFECTIVELY CAP ANY CONVECTIVE CHANCES ON TUESDAY. ADDITIONALLY...
THE LLVLS WILL BE SLIGHTLY COOLER BEHIND A WIND SHIFT THAT WILL
OCCUR EARLY TUESDAY. THE COMBINATION WILL RESULT IN A MORE CAPPED
ENVIRONMENT. HIGH TEMPERATURES ON TUESDAY WILL RETREAT FROM THE
TRIPLE DIGITS OVR THE WRN NEBRASKA PANHANDLE...WITH MID 80S TO MID
90S COMMON.

WEDNESDAY STILL LOOKS LIKE THE MOST CONVECTIVELY ACTIVE DAY OF THE
WEEK AS HEIGHTS FALL WITH THE APPROACH OF SHORTWAVE ENERGY.
MEANWHILE...INSTABILITY AXIS WILL AMPLIFY ALONG THE FRONT RANGE AND
ERN PLAINS PROGD SBCAPES OF 2500-3500 J/KG WILL BE FOUND OVR THE ERN
PLAINS. DEEP LAYER SHEAR LOOKS LESS IMPRESSIVE THAN IT DID ON
YESTERDAYS RUN...NOW ADVERTISING GENERALLY 25-35 KNOTS. THE
COMBINATION WILL DEFINITELY BE SUFFICIENT FOR A FEW STRONG TO
LOCALLY SEVERE STORMS WEDNESDAY AFTERNOON AND EVENING....ESPECIALLY
OVR LOCATIONS EAST OF THE LARAMIE RANGE. SE WYOMING LOOKS TO SEE THE
BEST SHOWER/THUNDERSTORM CHANCES DURING THE AFTERNOON HOURS...WITH
LOCATIONS IN THE WRN NEBRASKA PANHANDLE HOLDING OFF UNTIL THE
EVENING. UNSEASONABLE WARMTH CONTINUES ON WEDNESDAY WITH HIGHS AGAIN
REACHING THE MID 80S TO MID 90S.

.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 345 PM MDT MON JUL 21 2014

MEDIUM RANGE MODEL GUIDANCE IS IN EXCELLENT AGREEMENT THROUGH MOST
OF THE EXTENDED FCST PERIOD. STRONG SHORTWAVE MOVES NORTH INTO THE
NORTHERN HIGH PLAINS FROM THE INTERMOUNTAIN WEST WITH CONTINUED
UPPER RIDGING ON THU. AS SUCH...THU WILL BE THE WARMEST DAY OF THE
PERIOD WITH BOTH THE ECMWF AND GFS SHOWING H7 TEMPS ABOVE 17 C FOR
MOST OF THE CWA. MAY SEE ONE MORE DAY OF TRIPLE DIGITS IN THE NE
PANHANDLE AS MOS GUIDANCE WOULD SUGGEST. THE MODELS SUGGEST A
FLATTENING UPPER RIDGE INTO THE WEEKEND...WITH ZONAL FLOW BECOMING
THE RULE UNTIL EARLY NEXT WEEK. A FEW IMPULSES WILL TRAVERSE THE
FLOW ALONG THE EDGE OF THE RIDGE ALONG WITH SOME SHOTS OF MONSOONAL
MOISTURE. CONTINUED LOW-END POPS EACH AFTN AND EVE...MAYBE LINGERING
INTO THE OVERNIGHT HOURS SOME NIGHTS. THE BEST CHANCES FOR PCPN LOOK
TO BE ON SUN AND MON AS LLVL UPSLOPE RETURNS TO THE LARAMIE RANGE
AND ADJACENT HIGH PLAINS. TEMPERATURES WILL BE NEAR TO SLIGHTLY
ABOVE NORMAL THROUGH THE WEEKEND WITH THE LACK OF ANY NOTABLE
WEATHER SYSTEMS. CERTAINLY SOME RELIEF FROM THE HEAT.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY AFTERNOON)
ISSUED AT 529 PM MDT MON JUL 21 2014

THROUGH 02Z...ISOLATED THUNDERSTORMS PRIMARILY AFFECTING THE
SCOTTSBLUFF AND ALLIANCE TAFS PRODUCING GUSTY AND ERRATIC WINDS
TO 45 KNOTS...THEN WINDS DIMINISHING. VFR PREVAILS ON TUESDAY WITH
NO THUNDERSTORMS EXPECTED.

&&

.FIRE WEATHER...
ISSUED AT 345 PM MDT MON JUL 21 2014

CRITICAL CONDITIONS WILL CONTINUE ACROSS THE SOUTHEAST WYOMING
PORTION OF THE DISTRICT THROUGH SUNSET. THE RED FLAG WARNING REMAINS
IN EFFECT FOR FWZ301-302-306 THROUGH 8 PM. WILL ALSO SEE SOME
ISOLATED SHOWER AND WEAK THUNDERSTORM ACTIVITY INTO THE EVENING AS
WELL...PARTICULARLY EAST OF THE LARAMIE RANGE. LITTLE IF ANY
RAINFALL IS ANTICIPATED FROM THIS ACTIVITY. DRY AND SLIGHTLY COOLER
CONDITIONS ARE EXPECTED FOR TUESDAY. ALTHOUGH MINIMUM RELATIVE
HUMIDITIES WILL REACH CRITICAL LEVELS AGAIN ON TUESDAY...WIND GUSTS
OF LESS THAN 20 MPH WILL LIMIT ANY FIRE WEATHER CONCERNS. MONSOONAL
MOISTURE PLUME WILL RETURN ON WEDNESDAY. THIS MOISTURE COMBINED WITH
A PASSING WEATHER DISTURBANCE WILL SET THE STAGE FOR THE BEST CHANCE
FOR SHOWERS AND THUNDERSTORMS OF THE WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR WYZ301-302-306.

NE...NONE.
&&

$$

SHORT TERM...HAHN
LONG TERM...HAMMER
AVIATION...RUBIN
FIRE WEATHER...HAHN





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