Area Forecast Discussion
Issued by NWS Cheyenne, WY

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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 300922
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
322 AM MDT TUE JUN 30 2015

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 300 AM MDT TUE JUN 30 2015

UPPER HIGH CENTERED NR SLC PER MORNING SATELLITE IMAGERY. STRONG
SHORTWAVE SPINNING INTO SRN ALBERTA THIS MORNING...WITH EMBEDDED
WEAKER SHORTWAVES AND ASSOCIATED MOISTURE EVIDENT TO ITS SOUTH
ROTATING THRU THE NRN ROCKIES. A LULL IN NOCTURNAL CONVECTION
LOCALLY TONIGHT...THOUGH UPSTREAM RADARS DO SHOW SOME WK SHOWERS
ACROSS NRN WY AND MT AT THIS HOUR. UPPER HIGH TO DRIFT EVER SO
SLOWLY SOUTH TODAY AS AFOREMENTIONED SHORTWAVES RIDE THE TOP OF THE
RIDGE AND DIVE SOUTHEAST INTO THE HIGH PLAINS. THEIR ASSOCIATED
REFLECTED BOUNDARY AT THE SURFACE ALONG WITH THE TERRAIN WILL BE
THE CATALYST FOR SCATTERED AFTERNOON/EVENING THUNDERSTORMS.
INSTABILITY PROGS ARE SIGNIFICANTLY DIFFERENT LATER TODAY DUE TO
AROUND 10F VARIATION IN LOW LEVEL DEWPOINTS. GFS HANDLED INITIAL
CONDITIONS POORLY WITH SOME AREAS ALREADY OFF BY 5-10F...SO
FAVORED BETTER MOISTURE AVAILABILITY PER THE NAM. AS SUCH...EXPECT
SHOWERS CURRENTLY IN BIG HORN AND WIND RIVER BASINS TO CONTINUE TO
ROTATING EAST/SOUTHEAST REACHING NRN CARBON AND CONVERSE COUNTIES
LATER THIS MORNING. CONVECTIVE COVERAGE WILL INCREASE ACROSS THE
REST OF THE CWFA THRU THE REMAINDER OF THE AFTERNOON. 0-6 KM SHEAR
VALUES OF 30-40 KNOTS ALONG WITH ANTICIPATED MLCAPES 500-1000 J/KG
SUGGEST A FEW OF THESE STORMS MAY BECOME STRONG CONTAINING SMALL
HAIL AND GUSTY WINDS. SEVERE THREAT SHOULD REMAIN FAIRLY LOW...THOUGH
WOULD NOT BE SURPRISED TO SEE A COUPLE NECESSITATE A WARNING LATER
TODAY. CONVECTION WILL DISSIPATE BY LATE EVENING WITH THE DEPARTURE
OF THE SHORTWAVE AND SURFACE HEATING.

UPPER HIGH WILL FLATTEN AND BEGIN SHIFTING WEST THRU THE GREAT BASIN.
MODELS SUGGEST ADDITIONAL WEAK SHORTWAVE ENERGY ROTATING AROUND
THE HIGH PERIPHERY ALONG WITH LOW LEVEL CONVERGENCE ALONG THE
FRONT RANGE WILL BE ENOUGH FOR ANOTHER ROUND OF ISOLATED
THUNDERSTORMS WEDNESDAY AFTERNOON...LIKELY LINGERING INTO THE
OVERNIGHT HOURS. INSTABILITY/SHEAR PARAMETERS LOOK SIMILAR FOR
WEDNESDAY...SO AGAIN WOULD NOT BE SURPRISED TO ENCOUNTER A FEW
STRONGER STORMS. FORTUNATELY TEMPERATURES WILL BE AROUND 5F
COOLER...WHICH MAY INHIBIT THE AVAILABLE INSTABILITY.

ACTIVE NORTHWEST FLOW TO CONTINUE ON THURSDAY AS THE UPPER HIGH
CONTINUES TO RETROGRADE TOWARDS NW NEVADA AND WEAKEN. THE NEXT
SHORTWAVE WILL BE DIVING SOUTH/SOUTHEAST THRU THE DAKOTAS BY
DAYBREAK THURSDAY WITH ITS ASSOCIATED SURFACE BOUNDARY ALREADY
THRU THE CWFA. THE FROPA TIMING WILL JUST NOT BE OPTIMAL FOR ANY
SIGNIFICANT CONVECTIVE CHANCES...THOUGH STILL CANT RULE OUT SOME
ISOLATED ACTIVITY MAINLY IN THE VICINITY OF THE SOUTHEAST WYOMING
MOUNTAINS AND THE SRN NEBRASKA PANHANDLE WHERE UPSLOPE FLOW AND
PROXIMITY OF THE SHORTWAVE ARE MAXIMIZED.

TEMPERATURES WILL BE SHY OF RECORDS TODAY WITH HIGH TEMPERATURES
EXPECTED TO REACH WELL INTO THE 90S MOST PLACES. WOULD NOT BE
SURPRISED TO SEE A FEW TRIPLE DIGITS ALONG THE NORTH PLATTE RIVER
VALLEY IN W NEBRASKA. HIGH TEMPERATURES WILL COOL BACK INTO THE
80S/LOW 90S FOR WEDNESDAY AND 80S VIRTUALLY EVERYWHERE FOR THURSDAY.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 300 AM MDT TUE JUN 30 2015

MEDIUM RANGE MODEL SOLUTIONS HAVE BEEN CONSISTENT WITH THE UPPER
RIDGE POSITION OVER THE GREAT BASIN AND MEAN TROUGH OVER THE
GREAT LAKES/MIDWEST LATE THIS WEEK. WEAK DISTURBANCES TRACKING
SOUTHEAST FROM THE NORTHERN ROCKIES INTO THE HIGH PLAINS WILL
TRIGGER ISOLATED TSTORM ACTIVITY WHICH SHOULD PASS NORTH AND EAST
OF THE REGION. CANNOT RULE OUT AN ISOLATED TSTORM OR TWO OVER THE
SOUTHEAST WY MOUNTAINS UNDER FAVORED OROGRAPHIC FLOW. TEMPERATURES
FRIDAY WILL AVERAGE A FEW DEGREES BELOW NORMAL WITH MID 70S TO MID
80S.

THE CENTER OF THE UPPER RIDGE MOVES BACK EAST TOWARD THE FOUR
CORNERS THIS WEEKEND. 700MB TEMPERATURES RISE TO NEAR 20C SATURDAY...
EQUATING TO HIGH TEMPERATURES IN THE MID 80S TO LOWER 90S. TSTORM
CHANCES WILL BE LESS THAN 15 PERCENT SATURDAY. A WEAK FRONT AND
SHORTWAVE PASS THROUGH THE CWA SUNDAY WITH 20 TO 25 PERCENT POPS
ALONG AND WEST OF THE LARAMIE RANGE WITH MARGINAL INSTABILITY. THE
PLAINS WILL BE CAPPED FOR CONVECTION DESPITE THE SOUTHEAST FLOW.
IT WILL BE A SMIDGE COOLER SUNDAY...ESPECIALLY NORTH AND WEST
PORTIONS OF THE CWA. A WEAK SURFACE LOW AND TROUGH OVER EAST
CENTRAL/SOUTHEAST WY COMBINED WITH AFTERNOON HEATING AND UPSLOPE
WILL KEEP SLIGHT CHANCES FOR AFTERNOON TSTORMS IN THE FORECAST.
HIGH TEMPERATURES MONDAY WILL BE A CARBON COPY OF SUNDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 300 AM MDT TUE JUN 30 2015

VFR CONDITIONS WILL PREVAIL...EXCEPT FOR MVFR VISIBILITY WITH
SCATTERED AFTERNOON/EVENING SHOWERS/TSTORMS. SMALL HAIL AND
GUSTY/ERRATIC WINDS WILL BE POSSIBLE WITH THE STRONGER STORMS.
LIGHT SURFACE WINDS THIS MORNING WILL SHIFT TO THE NORTHWEST
WITH THE PASSAGE OF A COOL FRONT.

&&

.FIRE WEATHER...
ISSUED AT 300 AM MDT TUE JUN 30 2015

STRONG GREAT BASIN HIGH PRESSURE WILL WEAKEN AS IT SLOWLY SHIFTS
WEST THIS WEEK. ONE MORE HOT DAY AHEAD TODAY WITH AFTERNOON HIGH
TEMPERATURES WARMING INTO THE 90S FOR MOST PLACES. SCATTERED
THUNDERSTORM CHANCES WILL RETURN TO THE DISTRICTS TODAY THROUGH
THURSDAY AS A SERIES OF WEATHER DISTURBANCES MOVE THROUGH. THIS
SHOWER ACTIVITY ALONG WITH A COOLING TREND AFTER TODAY WILL KEEP ANY
CRITICAL FIRE WEATHER CONDITIONS AT BAY THROUGH THE END OF THE WEEK.

&&

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

$$

SHORT TERM...CAH
LONG TERM...MAJ
AVIATION...MAJ
FIRE WEATHER...CAH



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