Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 292110
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
310 PM MDT TUE JUL 29 2014

.SHORT TERM...(TONIGHT THROUGH THURSDAY NIGHT)
ISSUED AT 200 PM MDT TUE JUL 29 2014

HEAVY RAIN EVENT JUST STARTING WITH CONVECTION DEVELOPING OVER
ALBANY COUNTY NEAR LARAMIE AND UP NEAR SHIRLEY BASIN AT NOON
TODAY. STORMS ARE VERY EFFICIENT RAIN PRODUCERS. PLEASE SEE HYDRO
SECTION BELOW. FORECAST CHALLENGES DEAL WITH TIMING/LOCATION OF
HEAVY RAINFALL THROUGH WEDNESDAY AFTERNOON.

CURRENTLY...WATER VAPOR SHOWING UPPER SHORTWAVE MOVING INTO
NORTHEASTERN UTAH THIS AFTERNOON. SURFACE ANALYSIS SHOWING
STATIONARY FRONT LAYING ACROSS SOUTHWESTERN WYOMING TO JUST NORTH
OF RAWLINS...THEN SOUTHEAST BY SARATOGA...INTO NORTHEASTERN
COLORADO. MOSAIC RADAR SHOWS MOST OF WESTERN WYOMING UNDER
WIDESPREAD RAIN WITH NORTHERN COLORADO FILLING IN THE PAST FEW
IMAGES. STORMS THAT HAVE DEVELOPED IN THE CWFA ARE VERY SLOW
MOVING...WITH A GENERAL WEST TO NORTHWEST MOVEMENT OF 5-10KTS OR
LESS.

GUIDANCE CONTINUES TO FILL IN OUR WESTERN COUNTIES WEST OF THE
LARAMIE RANGE THIS AFTERNOON...SPILLING OVER INTO THE EAST SLOPES
AFTER 22Z TODAY. PWATS HERE AT CHEYENNE CONTINUE TO CLIMB THIS
AFTERNOON...UP TO 1.36 INCHES BY MID EVENING. VERY SLOW MOVEMENT
ON CELLS..UNDER 10KTS THIS AFTERNOON AND EVENING.

VERY STRONG UPSLOPING WINDS THIS EVENING. GFS AND NAM SHOWING 20KT
AT 700MBS THIS EVENING. SO WE ARE GOING TO HAVE A PRETTY GOOD
UPSLOPING EVENT FOR AREAS EAST OF THE LARAMIE RANGE. THINK THAT WE
WILL SEE A FAIRLY WIDESPREAD STRATIFORM EVENT WITH MODERATE
RAIN...MAYBE SOME ISOLATED THUNDERSTORMS EMBEDDED IN THE STRATUS.
WENT AHEAD AND UPPED POPS AND CONTINUED HEAVY RAIN THROUGH
WEDNESDAY AFTERNOON.
STRONG SHORTWAVE MOVES THROUGH INTO COLORADO WEDNESDAY NIGHT WITH
RAIN ENDING FROM NORTH TO SOUTH. RAIN TO COME TO AN END BY
MIDNIGHT THURSDAY MORNING.

.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 310 PM MDT TUE JUL 29 2014

LONG RANGE MODELS SHOW LITTLE CHANGE TO THE OVERALL WEATHER
PATTERN INTO NEXT WEEK...WITH A BROAD UPPER LEVEL RIDGE OVER THE
WESTERN THIRD OF THE UNITED STATES AND A LARGE SCALE TROUGH OVER
THE OTHER TWO THIRDS OF THE COUNTRY. WITH THE EXCEPTION OF THE
RELATIVELY STRONG TROUGH OVER THE EASTERN UNITED STATES...THIS
PATTERN IS TYPICAL FOR EARLY AUGUST WITH MONSOON FLOW OVER THE
WEST. THEREFORE...CAN NOT RULE OUT A DAILY CHANCE OF SHOWERS AND
TSTORMS ACROSS MOST OF THE FORECAST AREA THROUGH THE WEEKEND.
MODELS SHOW PW/S INCREASING OVER ONE INCH ACROSS THE FORECAST
AREA THIS WEEKEND WITH DECENT LLVL INSTABILITY. WEAK SHORTWAVE
ENERGY MAY ENHANCE THE POTENTIAL FOR SHOWERS AND TSTORMS AS WELL
FRIDAY AND AGAIN ON SUNDAY. KEPT POP BETWEEN 20 TO 40 PERCENT
MAINLY ACROSS SOUTHEAST WYOMING...WITH VALUES BELOW 20 PERCENT
ACROSS WESTERN NEBRASKA DUE TO DRY AIR ALOFT. TEMPERATURES WILL BE
NEAR OR SLIGHTLY BELOW NORMAL WITH HIGHS IN THE 70S TO MID 80S.
SUNDAY APPEARS TO BE THE WARMEST DAY AHEAD OF A WEAK COOL
FRONT...WITH HIGHS IN THE 80S TO NEAR 90 POSSIBLE.

PRECIPITATION AND TSTORM CHANCES INCREASE EARLY NEXT WEEK WITH ALL
MODELS SHOWING A STRONG SHORTWAVE MOVING CLOCKWISE AROUND THE
UPPER LEVEL HIGH. THE AXIS OF MONSOON MOISTURE WILL BE RIGHT ALONG
THE FRONT RANGE BY MONDAY AND TUESDAY. THE ECMWF SHOWS THIS
SHORTWAVE BECOMING NEARLY STATIONARY ACROSS THE AREA AS WELL.
CONTINUED TO INCREASE POP EARLY NEXT WEEK WITH A FAVORABLE HEAVY
RAINFALL PATTERN WITH EAST TO SOUTHEAST UPSLOPE FLOW AND GOOD
INSTABILITY ALONG WITH PLENTY OF MOISTURE. A WEAK COOL FRONT WILL
PUSH ACROSS THE REGION...WHICH WILL RESULT IN COOLER THAN NORMAL
TEMPERATURES OVER THE AREA. LOWERED TEMPERATURES ON TUESDAY...INTO
THE MID TO UPPER 70S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH NOON WEDNESDAY)
ISSUED AT 159 PM MDT TUE JUL 29 2014

WIDESPREAD RAIN AND THUNDERSTORMS WILL CONTINUE INTO LATE THIS
EVENING ACROSS MOST OF THE AREA...WITH THE EXCEPTION OF KCDR AND
KAIA WHICH WILL LIKELY BE NORTH OF THE HEAVIEST RAINFALL.
THUNDERSTORMS WILL GRADUALLY BECOME MORE ISOLATED AFTER MIDNIGHT
WITH THE LOSS OF SURFACE HEATING. HOWEVER...HEAVY RAINFALL IS
EXPECTED TO CONTINUE ACROSS MOST TERMINALS...ESPECIALLY SOUTHEAST
WYOMING AND FAR WESTERN NEBRASKA. KEPT IFR VIS DUE TO VERY HEAVY
RAIN...WITH THE POSSIBILITY FOR FOG AND LOW CIGS NEAR THE LARAMIE
RANGE. RAIN IS EXPECTED TO CONTINUE THROUGH WEDNESDAY MORNING.

IN ADDITION...LLVL WINDS WILL INCREASE NEAR THE LARAMIE RANGE AS A
700MB LOW DEVELOPS NEAR THE COLORADO/WYOMING BORDER TONIGHT. THIS
MAY RESULT IN STRENGTHENING SURFACE WINDS AND WIND DRIVEN RAIN FROM
KCYS...WESTWARD TO KRWL TONIGHT.

&&

.FIRE WEATHER...
ISSUED AT 200 PM MDT TUE JUL 29 2014

MINIMAL FIRE WEATHER CONCERNS. A STRONG STORM SYSTEM COMBINED
WITH MONSOON MOISTURE WILL GIVE WAY TO WIDESPREAD SHOWERS AND
THUNDERSTORMS ON TUESDAY AND WEDNESDAY. THE GREATEST COVERAGE WILL
BE ALONG AND ON EITHER SIDE OF THE LARAMIE RANGE WHERE A GENERAL 1
TO 2 INCHES OF RAIN CAN BE EXPECTED. COOLER TEMPERATURES AND NEW
MOISTURE WILL MITIGATE ANY FIRE WEATHER CONCERNS THROUGH MID WEEK.

&&

.HYDROLOGY...
ISSUED AT 200 PM MDT TUE JUL 29 2014

ALMOST A TROPICAL ENVIRONMENT OVER THE CWFA THIS AFTERNOON. STORMS
ARE PRODUCING VERY HEAVY RAIN FALL AMOUNTS. FOR EXAMPLE...LARAMIE
RECEIVED OVER A HALF INCH OF RAINFALL IN 45 MINUTES AND A REPORT
TO THE NORTHEAST OF LARAMIE SHOWED ALMOST .9 INCHES OF RAIN IN
JUST 35 MINUTES. FORECAST IS STILL ON TRACK WITH HEAVY RAIN
BECOMING MORE WIDESPREAD AS THE AFTERNOON WEARS ON. THINK WE WILL
BE SEEING MANY LOCATIONS WITH 1+ INCHES OF RAINFALL THIS AFTERNOON
AND EVENING. FLASH FLOOD WATCH CONTINUES.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...

WY...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR WYZ103-106-112-
     114>118.

NE...NONE.
&&

$$

SHORT TERM...CLAYCOMB
LONG TERM...TJT
AVIATION...TJT
FIRE WEATHER...CLAYCOMB
HYDROLOGY...CLAYCOMB








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