Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 081028
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
428 AM MDT TUE JUL 8 2014

.SHORT TERM...(TODAY THROUGH THURSDAY NIGHT)
ISSUED AT 428 AM MDT TUE JUL 8 2014

SFC HIGH CENTERED OVR MONTANA WILL WEAKEN AS IT SLIDES SOUTHEAST
ALONG THE FRONT RANGE AND INTO THE PLAINS TODAY. IN THE WAKE OF
YESTERDAYS COOL FROPA...SFC DEW POINTS HAVE INCREASED...NOW IN THE
50S AT MOST SITES. THESE MOIST SFC CONDITIONS HAVE COMBINED WITH
PERSISTENT NORTHEAST UPSLOPE FLOW TO SPARK A FEW SHOWERS AND WK
THUNDERSTORMS EARLIER THIS MORNING OVR LARAMIE AND KIMBALL
COUNTIES. THIS CONVECTIVE ACTIVITY HAS SINCE SHIFTED SOUTH INTO
COLORADO AND WEAKENED. 09Z 11-3.9 SATELLITE FOG PRODUCT SHOWS
FAIRLY EXTENSIVE AREA OF LOW CLOUDS EXTENDING FROM CENTENNIAL AND
ARLINGTON AREAS EAST TO HAWK SPRINGS AND PINE BLUFFS. THESE LOW
CLOUDS WHICH ARE AROUND 4500 FEET AT 09Z AT KCYS INTERCEPT THE
LARAMIE RANGE CLOSE TO THE SUMMIT. FOG LOOKS FAIRLY THIN RIGHT
NOW...BUT DID ADD ITS MENTION THERE THRU 15Z. OTHERWISE...TODAY
LOOKS TO BE A TRANSITION DAY AS DRY NORTHWEST FLOW RIDES ATOP
RELATIVELY COOL POST-FRONTAL LLVLS. FORECAST SOUNDINGS SHOW STOUT
CAP AROUND H7. MID-LEVEL MOISTURE MAY INCREASE ENOUGH TO GET SOME
WK CONVECTION GOING NR THE MOUNTAINS BY LATE THIS AFTERNOON. IF
ABLE TO DEVELOP...THIS ACTIVITY WOULD BE ANCHORED TO THE TERRAIN.
OTHERWISE...EXPECT A NOTICEABLY COOLER DAY TODAY AS HIGHS ONLY
REACH THE 70S AND LOW 80S.

UPPER-LEVEL HIGH PRESSURE WILL SHIFT SOUTHEAST INTO THE SRN
PLAINS BY LATE WEDNESDAY. THIS WILL CAUSE MID-LEVEL HEIGHTS TO
FALL AS SUB-TROPICAL MOISTURE ASSOCIATED WITH EMBEDDED SHORTWAVE
ENERGY ROTATES INTO THE CWFA. MODELS SUGGEST A RELATIVELY LATE
ARRIVAL OF THIS MOISTURE...REACHING CARBON/ALBANY COUNTIES BY
LATE AFTERNOON. ERLY UPSLOPE FLOW WILL COMBINE WITH 1000-2000 J/KG
SBCAPE AXIS TO PRODUCE A DECENT COVERAGE OF AFTERNOON
SHOWERS/THUNDERSTORM...EARLIEST OVR WRN ZONES BEFORE SPREADING
EAST IN THE EVENING. DEEP LAYER SHEAR OF 30-40 KNOTS SUGGEST A FEW
MAY BECOME STRONG OR BORDERLINE SEVERE EAST OF THE LARAMIE RANGE.
TEMPERATURES WILL BE WARMER ON WEDNESDAY WITH HIGHS RETURNING INTO
THE 80S AND 90S FOR ALL LOWER ELEVATIONS. ANOTHER SHORTWAVE WILL
MOVE THRU WEDNESDAY NIGHT...SUSTAINING THE POSSIBILITY OF
NOCTURNAL CONVECTION. BOTH THE NAM/GFS PAINT BEST NOCTURNAL PRECIP
CHANCES ACROSS EAST CENTRAL WYOMING AND THE NRN NEBRASKA
PANHANDLE. HOWEVER...HAVE BEEN FAIRLY LIBERAL WITH PRECIP
COVERAGE AS MODELS HAVE TROUBLE PINPOINTING NOCTURNAL CONVECTIVE
LOCATIONS.

ADDITIONAL SHORTWAVE ENERGY WILL MOVE THRU FOR THURSDAY AND WHEN
COMBINED WITH MORE SUB-TROPICAL MOISTURE ROTATING AROUND THE
UPPER-HIGH...EXPECT ANOTHER ROUND OF PRIMARILY AFTERNOON/EVENING
CONVECTION. CONVECTIVE COVERAGE WILL BE BETTER ON THURSDAY...
ESPECIALLY FOR AREAS EAST OF THE LARAMIE RANGE. INSTABILITY AND
SHEAR PARAMETERS WILL BE SIMILAR ON THURSDAY AS WEDNESDAY. THIS
POINTS AGAIN TO AT THE LEAST THE POTENTIAL FOR A FEW STRONG OR
SEVERE STORMS EAST OF THE LARAMIE RANGE THURSDAY. TEMPERATURES
WILL BE A DEGREE OR TWO WARMER ON THURSDAY.

.LONG TERM...(FRIDAY THROUGH MONDAY)
ISSUED AT 428 AM MDT TUE JUL 8 2014

OUT OF ALL THE DAYS IN THE EXTENDED...IT APPEARS THAT FRI COULD
BE THE MOST CONVECTIVELY ACTIVE. THE MIDLVL MONSOONAL RIDGE SHIFTS
EASTWARD INTO NORTHERN NEW MEXICO WITH GOOD 700-500MB SUBTROPICAL
MOISTURE MOVING ACROSS THE CWA. PW VALUES ARE QUITE
HIGH...GENERALLY 1.25-1.5 INCHES ACROSS THE PLAINS. WITH A WEAK
SHORTWAVE MOVING OVERHEAD AND INTERACTING WITH THIS
MOISTURE...HAVE WIDESPREAD CHANCE POPS ON FRI. FLOW ALOFT BECOMES
MORE NORTHWESTERLY ON SAT AND SUN AS THE SUBTROPICAL RIDGE SHIFTS
WESTWARD. NOT EXPECTING AS MUCH TSTM COVERAGE ON THESE
AFTNS...ALTHOUGH AT LEAST SLIGHT CHANCE POPS ARE WARRANTED. COLD
FRONT PUSHES THROUGH THE AREA LATE ON SUN WHICH WILL RESULT IN
SLIGHTLY COOLER TEMPS FOR EARLY NEXT WEEK. IT APPEARS THAT FLOW
ALOFT WILL BE STRONG ENOUGH TO PROMOTE 25-40 KTS OF BULK SHEAR
EACH AFTN FROM FRI THROUGH MON...SO THERE WILL LIKELY BE A THREAT
OF STRONG TO MARGINALLY SVR STORMS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 114 AM MDT TUE JUL 8 2014

MAINLY VFR CONDITIONS ACROSS THE REGION EXCEPT IN AREAS NEAR THE
LARAMIE RANGE. MOIST EAST TO SOUTHEAST WINDS WILL PRODUCE IFR CIGS
AT CYS AND MVFR CIGS AT LAR THROUGH 12Z. ELSEWHERE...SKIES WILL
GENERALLY BE CLEAR THROUGH THE NIGHT. THE POST FRONTAL AIRMASS
WILL BE MORE STABLE ON TUES AFTN...SO NOT EXPECTING STORMS TO
IMPACT THE TERMINALS.

&&

.FIRE WEATHER...
ISSUED AT 428 AM MDT TUE JUL 8 2014

A MOSTLY DRY AND RELATIVELY COOL DAY AHEAD ACROSS THE DISTRICTS
TODAY. THERE MAY BE JUST ENOUGH MOISTURE AVAILABLE FOR AN ISOLATED
SHOWER OR THUNDERSTORM OVER THE MOUNTAINS BY LATE IN THE AFTERNOON.
CHANCE OF WETTING RAINS WILL NOT BE ALL THAT GREAT FROM THIS
ACTIVITY AS MOISTURE REMAINS LIMITED. GUSTY OUTFLOW WINDS WILL BE
POSSIBLE WITH ANY OF THIS ACTIVITY. THIS ACTIVITY WILL DISSIPATE BY
SUNSET. BETTER CHANCES FOR MOSTLY AFTERNOON/EVENING SHOWER AND
THUNDERSTORM ACTIVITY WILL RETURN FOR WEDNESDAY AND MORE SO ON
THURSDAY AS SLUG OF SUB-TROPICAL MOISTURE MOVES INTO THE REGION.
TEMPERATURES WILL RETURN BACK TO NORMAL VALUES WED-THU AS WELL.
MINIMUM RELATIVE HUMIDITIES WILL DROP INTO THE TEENS WEST AND 20S
EAST THROUGH FRIDAY.

&&

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

&&

$$

SHORT TERM...HAHN
LONG TERM...FINCH
AVIATION...FINCH
FIRE WEATHER...HAHN





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