Area Forecast Discussion
Issued by NWS Cheyenne, WY

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS65 KCYS 072354
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
554 PM MDT TUE JUL 7 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 300 PM MDT TUE JUL 7 2015

SHOWERS AND THUNDERSTORMS ARE BECOMING MORE PREVALENT THROUGH THE
AFTERNOON ALONG AND WEST OF THE LARAMIE RANGE AS THE SHORTWAVE
EVIDENT ON WATER VAPOR APPROACHES FROM THE WEST. AMSU-SSM/I
PRECIPITABLE WATER PLOTS SHOW PW VALUES ROUGHLY 100-120% OF NORMAL
OVER OUR FORECAST AREA...WITH DEEP LAYER MEAN WINDS OF 10-15 KTS
ANALYZED ACROSS SOUTHEAST WYOMING. LOW/MID CLOUDS THINNED QUITE A
BIT OVER SOUTHEAST WYOMING THROUGH THE LATE MORNING AND EARLY
AFTERNOON AS WELL...ALLOWING SOME SUNSHINE TO REACH THE SURFACE. AS
A RESULT...SBCAPES OF 500 TO 1000 J/KG ARE CURRENTLY OVER SOUTHEAST
WYOMING FROM EAST TO WEST...WITH MUCH LESS OVER THE PANHANDLE WHERE
LOW/MID LEVEL CLOUDS ARE MUCH SLOWER TO BREAK UP. WITH THIS
COMBINATION OF PARAMETERS...EXPECT MUCH OF THE CONVECTIVE ACTIVITY
TO REMAIN OVER SOUTHEAST WYOMING ESPECIALLY FROM THE SIERRA MADRES
EASTWARD TOWARD THE LARAMIE RANGE WHERE OROGRAPHIC FORCING AND
COMBINES WITH SHORTWAVE ENERGY. STILL THINKING THAT SOME STORMS
COULD BECOME STRONG OVER THIS AREA WITH INSTABILITY...LIGHT
WINDS...AND HIGH PW`S IN PLACE...SO SMALL HAIL AND HEAVY RAINFALL
ARE STILL A HIGH POSSIBILITY. THEREFORE...MAINTAINED THE FLASH FLOOD
WATCH AS IS FOR THE POSSIBILITY OF OVER AN INCH OF NEW RAINFALL IN A
SHORT AMOUNT OF TIME OVER ALREADY SATURATED SOILS IN THESE AREAS. A
FEW SHOWERS/STORMS COULD TREK EASTWARD INTO THE NEBRASKA PANHANDLE
AS WELL THIS EVENING SO KEPT A 20-40 PERCENT CHANCE HERE...ALTHOUGH
RAINFALL FROM THIS ACTIVITY SHOULD BE MUCH LESS. LLVL SOUTH-
SOUTHEASTERLY FLOW ACROSS THE EASTERN PLAINS WILL LIKELY REDEVELOP
UPSLOPE FOG AND DRIZZLE OVER THE LARAMIE RANGE...BUT NOT CONFIDENT
WITH  TIMING NOR HOW LOW VISIBILITIES WILL GO DUE TO EXPECTED
INTERMITTENT CONVECTION OVERNIGHT SO WILL HOLD OFF ON ANY FOG
ADVISORIES FOR NOW.

WEDNESDAY CONTINUES TO LOOK ACTIVE WITH ANOTHER SHORTWAVE TROUGH
MOVING UP FROM THE SOUTHWEST. THE FOCUS FOR STRONGER ACTIVITY LOOKS
TO PUSH FURTHER EAST CLOSER TO THE LARAMIE RANGE...ALTHOUGH HEAVY
RAIN IS STILL A POSSIBILITY OVER THE HIGHER PEAKS OF THE SNOWIES AND
SIERRA MADRES. STILL THINKING WILL NEED TO REISSUE FLASH FLOOD
WATCHES FOR TOMORROW BUT IT WILL ULTIMATELY DEPEND ON TODAYS
ACTIVITY.

THURSDAY CONTINUES TO LOOK DRIER OVERALL WITH SHORTWAVE RIDGING AND
WARMER TEMPS MOVING OVERHEAD...HOWEVER HIGHER INSTABILITY OF 500-
2000 J/KG IS PROGGED OVER A BROADER PORTION OF THE CWA WHILE A
SHORTWAVE MOVES OVERHEAD MIDDAY...SO WILL STILL SEE SHOWERS AND
STORMS DEVELOP IN THE LATE MORNING AND CONTINUE THROUGH THURSDAY
EVENING.

.LONG TERM...(FRIDAY THROUGH MONDAY)
ISSUED AT 300 PM MDT TUE JUL 7 2015

IT WILL BE A MOSTLY WARM AND DRY EXTENDED PERIOD AS THE
SUBTROPICAL RIDGE STRENGTHENS TO THE SOUTH OF THE AREA.
STRONG SOUTHWESTERLY FLOW ALOFT WILL BE IN PLACE ON FRI WITH A
DRIER AIRMASS MOVING INTO AREAS WEST OF THE LARAMIE RANGE. THERE
IS SOME DISAGREEMENT BETWEEN THE GFS AND ECMWF OVER THE AMOUNT OF
AFTN AND EVENING CONVECTION ACROSS THE PLAINS WITH THE WETTER
ECMWF LIKELY OVERDONE. KEPT POPS BELOW 30 PERCENT FOR NOW. THE LEE
TROUGH WILL REALLY BECOME ESTABLISHED BY SAT WITH THE BEST
MOISTURE AND INSTABILITY PUSHED WELL EAST OF THE CWA. IT WILL BE A
BREEZY DAY TO THE WEST OF THE LARAMIE RANGE AS 700MB WINDS OF
25-30 KTS MIX DOWN. NOT MUCH CHANGE FOR SUNDAY WITH DRY WESTERLY
BOUNDARY LAYER FLOW IN PLACE. WITH PW VALUES GENERALLY BELOW 0.5
INCHES OVER THE ENTIRE CWA ON SAT AND SUN...WILL HAVE TROUBLE
GETTING MUCH IF ANY CONVECTION GOING. TEMPS WILL WARM BACK UP TO
AROUND NORMAL FOR MID JULY BY THIS WEEKEND. HEIGHTS ALOFT CONTINUE
TO RISE OVER THE INTERMOUNTAIN WEST INTO EARLY NEXT WEEK WITH THE BREAK
IN THE MONSOONAL STORMS PERSISTING.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 550 PM MDT TUE JUL 7 2015

WYOMING TAFS...VFR PREVAILS AT RAWLINS WITH OCCASIONAL IFR IN
SHOWERS AND THUNDERSTORMS THROUGH 03Z. AT LARAMIE AND CHEYENNE...
BECOMING IFR OVERNIGHT IN FOG...RAIN AND LOW CLOUDS...THEN VFR
WEDNESDAY MORNING WITH OCCASIONAL MVFR IN SHOWERS AND
THUNDERSTORMS WEDNESDAY AFTERNOON.

NEBRASKA TAFS...VFR PREVAILS OVERNIGHT...EXCEPT FOR OCCASIONAL
IFR AT SIDNEY AND SCOTTSBLUFF IN FOG AND LOW CLOUDS...THEN
BECOMING VFR WEDNESDAY MORNING WITH OCCASIONAL MVFR IN SHOWERS
AND THUNDERSTORMS WEDNESDAY AFTERNOON.

&&

.FIRE WEATHER...
ISSUED AT 300 PM MDT TUE JUL 7 2015

WIDESPREAD SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THE
AFTERNOON AND EVENING AS A WEATHER DISTURBANCE AND PLENTIFUL
MOISTURE MOVE OVER THE DISTRICT. SOME OF THIS ACTIVITY COULD PRODUCE
VERY HEAVY RAINFALL MAINLY OVER SOUTHERN PORTIONS OF CARBON AND
ALBANY COUNTIES WHERE FLASH FLOODING IS POSSIBLE. WEDNESDAY WILL SEE
ANOTHER ROUND OF MODERATE TO HEAVY RAIN FROM SHOWERS AND
THUNDERSTORMS...WITH SOME OF THE HEAVIER ACTIVITY POSSIBLY AFFECTING
AREAS FURTHER TO THE EAST TOWARD THE LARAMIE RANGE. TEMPERATURES
WILL REMAIN BELOW NORMAL THROUGH THE END OF THIS WEEK BUT WILL TREND
WARMER OVER THE WEEKEND AS HIGH PRESSURE BEGINS TO BUILD OVERHEAD.
CONDITIONS WILL TREND DRIER AS WELL THROUGH THE WEEKEND. AS A RESULT
OF COOLER AND WET CONDITIONS...NO FIRE WEATHER CONCERNS ARE
ANTICIPATED IN THE NEAR TERM.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...FLASH FLOOD WATCH UNTIL MIDNIGHT MDT TONIGHT FOR WYZ109>116.

NE...NONE.
&&

$$

SHORT TERM...RJM
LONG TERM...ZF
AVIATION...RUBIN
FIRE WEATHER...RJM


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.