Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 100020 AAA
AFDCYS

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHEYENNE WY
620 PM MDT WED JUL 9 2014

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 342 PM MDT WED JUL 9 2014

THE SHORTWAVE FEATURE THAT BROUGHT SCATTERED SHOWERS AND TSTORMS TO
THE EASTERN PLAINS THIS MORNING IS EVIDENT ON WATER VAPOR IMAGERY
MOVING SOUTHEAST ACROSS THE CWA TODAY. THIS FEATURE IS RIDING ON
THE EASTERN PERIPHERY OF THE UPPER LEVEL RIDGE SITUATED FROM
MONTANA TO UTAH. ADDITIONAL MIDLEVEL ENERGY WILL CONTINUE TO APPROACH
FROM THE WEST THIS AFTERNOON AND EVENING AND WILL INDUCE LEESIDE
TROUGHING. LOOKING AT GUSTY EAST/SOUTHEAST SFC WINDS TO CONTINUE ACROSS
THE PLAINS...TURNING PERHAPS MORE NORTHEAST OVER THE NEXT FEW
HOURS ALONG THE CHEYENNE RIDGE ON THE NORTHERN EDGE OF A WEAK SFC
LOW DEVELOPING WITHIN THE SFC TROUGH IN NORTHERN COLORADO. MODELS
SHOW DEWPOINTS REMAINING IN THE LOW TO MID 50S ACROSS THE
PLAINS...WITH RESULTANT SBCAPE VALUES OF BETWEEN 1000 AND 2000
J/KG. THEREFORE...WILL CONTINUE TO ADVERTISE ISOLATED TSTORMS...WITH
A FEW STRONGER STORMS POSSIBLE THRU EARLY THIS EVENING WHERE DEEP
LAYER SHEAR IS ON THE ORDER OF 30 TO 40KTS. STRONGER SFC
CONVERGENCE IN EASTERN LARAMIE COUNTY/SOUTHERN NEBRASKA PANHANDLE
BETWEEN THE ZONE OF SOUTHEASTERLY WINDS AND NORTHEASTERLY WINDS
COULD FOCUS THE STRONGEST STORMS HERE. LOOKING AT LARGE HAIL THE
MAIN THREAT OUT OF THESE STORMS...WITH GUSTY WINDS A SECONDARY
CONCERN. FURTHER WEST ACROSS THE HIGH COUNTRY...MEAGER MIDLEVEL
MOISTURE WILL COMBINE WITH LI VALUES RANGING FROM MINUS 1 TO MINUS
2 TO SUPPORT A FEW TSTORMS...ESPECIALLY OVER THE HIGH PEAKS. WINDS
AT THE TOP OF THE MIXED LAYER WHICH WILL BE AROUND 550 TO 600 MB
ARE ONLY ABOUT 15 TO 20 KTS...SO DO THINK GUSTY AND ERRATIC WINDS
WILL BE AN ISSUE FROM TSTORMS BUT LIKELY ONLY AROUND 40 MPH OR SO.

A SHORTWAVE RIDING ATOP THE RIDGE AND OVER WYOMING TONIGHT COULD
MAINTAIN ISOLATED ACTIVITY...ESPECIALLY AS A WEAK LLVL JET DEVELOPS.
THIS SHORTWAVE WILL FLATTEN THE RIDGE AXIS FOR THURSDAY...ALLOWING A
BETTER FETCH OF MOISTURE AND STRONGER MIDLEVEL ENERGY TO MOVE
OVERHEAD THROUGH THE DAY. THE LEESIDE SFC TROUGH WILL SHIFT EAST
INTO NEBRASKA THRU THE MORNING WITH A WEAK COOL FRONT MOVING SOUTH
ACROSS THE CWA IN THE AFTERNOON. LOOKING AT A MORE SCATTERED
COVERAGE OF TSTORMS WITH COMBINATION OF SFC AND UPPER FORCING...AND
MORE AVAILABLE MOISTURE. PWATS WILL INCREASE TO BE ROUGHLY 1 TO 1.3
INCHES BY THE LATE AFTERNOON...SO LOOKING AT MAINLY A THREAT FOR
HEAVY RAIN AND PERHAPS SMALL TO MARGINALLY SEVERE HAIL WITH STORMS
AHEAD OF THE FRONT.

CONTINUED ENERGETIC AND VERY MOIST MONSOONAL FLOW WILL REMAIN
OVERHEAD FOR FRIDAY...WITH PWATS INCREASING SLIGHTLY BEHIND THE SFC
FRONT AS DEW POINTS INCREASE BACK INTO THE MID TO UPPER 50S/LOW 60S.
SFC WINDS WILL SWITCH TO BECOME MORE UPSLOPE IN NATURE BEHIND THE
FRONT AND AS A POTENT SHORTWAVE APPROACHES FROM THE WEST...INDUCING
THE EASTERLY SFC WIND COMPONENT. FORECAST SOUNDINGS SHOW QUITE A
MOIST PROFILE THROUGH THE ATMOSPHERIC COLUMN...WITH A BROADER
COVERAGE OF SHOWERS AND TSTORMS EXPECTED WITH THE COMBINATION OF SFC
AND MIDLEVEL FORCING. WITH THE MOIST PROFILE IN PLACE...EXPECT SOME
OF THIS ACTIVITY TO PRODUCE MODERATE TO HEAVY RAIN. WINDS ALOFT WILL
BE 15 TO 30 KTS...SO STORMS SHOULD MOVE AT A STEADY PACE EAST-
NORTHEASTWARD. HOWEVER...STILL THINK SOME OF THE STRONGER
ACTIVITY COULD PRODUCE ONE HALF INCH OR MORE OF QPF THROUGH FRIDAY
AFTERNOON...BUT ANY FLASH FLOOD THREAT WILL DEPEND ON THURSDAYS
ACTIVITY DUE TO THE RECENT DRY SPELL.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 342 PM MDT WED JUL 9 2014

UPPER HIGH OVER THE SOUTHERN PLAINS FRIDAY WILL RETROGRADE WEST
DURING THE WEEKEND WITH THE UPPER FLOW OVER THE CWA GRADUALLY
TURNING NW. THIS WILL ALLOW FOR SOME COOLER AIR TO SINK SE OVER
THE PLAINS WITH THE EDGE OF THESE AIR MASSES BACKING UP AGAINST
THE MTNS. NOT A LOT OF COOLING EXPECTED BUT UPSLOPE FLOW
ASSOCIATED WITH THESE COMBINED WITH WEAK IMPULSES RIDING SE OVER
THE REGION AND SOME MONSOONAL MOISTURE SHOULD KEEP CHANCES FOR
MAINLY AFTERNOON AND EVENING CONVECTION GOING ACROSS MUCH OF THE
CWA FOR MOST DAYS. DRIER CONDITIONS MAY ARRIVE BY WEDS AS BETTER
MOISTURE MAY GET SUPPRESSED SOUTHWARD. TEMPERATURES WARM THROUGH
THE PERIOD...GENERALLY IN THE VICINITY OF SEASONAL AVERAGES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY AFTERNOON)
ISSUED AT 620 PM MDT WED JUL 9 2014

VFR CATEGORY EXPECTED FOR ALL TAF SITES OVERNIGHT INTO TOMORROW
MORNING. CURRENT BATCH OF THUNDERSTORMS FROM CHEYENNE EAST ACROSS
EXTREME SOUTHERN NEBRASKA INTO NORTHERN COLORADO WILL CONTINUE TO
WEAKEN THROUGH EARLY EVENING AND SHOULD MISS THE AIRPORT FORECAST
SITES. WE MAY GET SOME ISOLATED SHOWERS LATER TONIGHT AROUND THE
WESTERN SITES (LARAMIE, RAWLINS)...BUT COVERAGE AND CONFIDENCE
LEVEL NOT HIGH ENOUGH TO WARRANT A MENTION IN THE AVIATION
FORECASTS THROUGH MORNING. WE DO EXPECT A GREATER COVERAGE OF
THUNDERSTORMS NEARLY AREA-WIDE TOMORROW AFTERNOON...SO PUT IN A
VICINITY MENTION OF THUNDERSTORMS AFTERNOON TOMORROW.


&&

.FIRE WEATHER...
ISSUED AT 342 PM MDT WED JUL 9 2014

DRY AND BREEZY CONDITIONS WILL CONTINUE WEST OF THE LARAMIE RANGE
THIS AFTERNOON...WITH HUMIDITIES RANGING FROM 10 TO 20 PERCENT
ACROSS THE LOWER ELEVATIONS AND GUSTS 20 TO 30 MPH.
ALSO...ISOLATED SHOWERS AND TSTORMS HAVE DEVELOPED OVER THE HIGH
PEAKS...AND WILL PRODUCE GUSTY DOWNDRAFT WINDS AND LIGHT RAIN
THROUGH THIS AFTERNOON. FURTHER EAST...SHOWERS AND TSTORMS WILL
EXPAND IN COVERAGE THRU THE LATE AFTERNOON...WITH HUMIDITIES
REMAINING 20 PERCENT OR HIGHER. AN ENERGETIC MONSOON FLOW PATTERN
WILL THEN OCCUR OVER THE DISTRICT THE NEXT FEW DAYS...WITH
INCREASING MOISTURE PRODUCING ISOLATED TO SCATTERED TSTORMS
THROUGH THE END OF THE WEEK. THIS ACTIVITY LOOKS TO PRODUCE WETTING
RAINS...WITH SOME LOCATIONS IN SOUTHEAST WYOMING POTENTIALLY
RECEIVING ONE HALF INCH OF QPF OR MORE ON FRIDAY.

&&

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

$$

SHORT TERM...RJM
LONG TERM...RE
AVIATION...GARMON
FIRE WEATHER...RJM





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