Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 131126
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
526 AM MDT SUN JUL 13 2014

.SHORT TERM...TODAY THROUGH TUESDAY NIGHT

THE SHOWERS AND THUNDERSTORMS OF LAST EVENING...ALL OF THE GARDEN
VARIETY...NON SEVERE TYPE HAVE ENDED AS OF NOW. MOST AREAS SHOULD
HAVE A DRY MORNING AS WELL. THERE COULD BE SOME LOCAL FOG IN AREAS
THAT SAW THE RAIN LAST EVENING. HOWEVER...WE DID NOT PUT ANY IN THE
GRIDS THIS MORNING SINCE IT SHOULD BE FAIRLY ISOLATED AND SHOULD
BURN OFF QUICKLY WITH THE STRONG JULY SUN. WITH HEIGHTS RISING A BIT
TODAY AS RIDGING OVER THE GREAT BASIN SHIFTS A BIT FURTHER EAST
TODAY...WE EXPECT SOMEWHAT LESS ACTIVITY THEN THE PREVIOUS FEW DAYS.
HOWEVER...WITH PRECIPITABLE WATER VALUES STILL APPROACHING ONE INCH
IN MANY LOCATIONS AND DEW POINTS REMAINING IN THE 50S THERE WILL
STILL BE ISOLATED ACTIVITY IN MANY AREAS. THE MOST ACTIVITY WILL BE
OVER THE MOUNTAINS WITH THE LEAST ACTIVITY OVER SOUTHWESTERN
WYOMING. WITH THE RIDGING STRENGTHENING...TEMPERATURES COULD BE A
FEW DEGREES WARMER IN SOME AREAS. MOST CONVECTION SHOULD END LATE
TONIGHT WITH THE LOSS OF DAYTIME HEATING.

THINGS MAY BECOME A BIT MORE ACTIVE FOR MONDAY HOWEVER. MODELS SHOW
A SHORT WAVE MOVING OVER THE TOP OF THE RIDGE FOR MONDAY AFTERNOON.
THIS SHOULD ENHANCE INSTABILITY AS WELL AS CREATE A BIT MORE SHEAR.
ALSO...THE MODELS SHOW SOMEWHAT HIGHER PRECIPITABLE WATER VALUES
RETURNING TO THE AREA WITH OVER 1 INCH VALUES IN THE BIG HORN
BASIN.  THE STORM PREDICTION CENTER HAS THE AREA IN A SEE TEXT AREA
WITH THE CHANCE OF SOME STRONGER STORMS. AT THIS TIME...WE WILL ADD
SOME ENHANCED WORDING FOR SMALL HAIL AND GUSTY WINDS. TEMPERATURES
MAY BE A BIT COOLER AS WELL WITH MORE CLOUD COVER.

IT COULD BE ANOTHER ACTIVE DAY ACROSS THE AREA FOR TUESDAY AS WELL.
A COMBINATION OF ANOTHER APPROACHING SHORTWAVE AND INCREASING UPPER
LEVEL DIVERGENCE WILL ONCE AGAIN DESTABILIZE THE ATMOSPHERE. IN
ADDITION...WE WILL HAVE THE FAVORED NORTHWESTERLY FLOW ALOFT THAT
FAVORS STRONGER THUNDERSTORMS. SHEAR PROFILES ARE ALSO EXPECTED TO
BECOME FAVORABLE ONCE AGAIN FOR THE POTENTIAL OF STRONGER STORMS.
THE STORM PREDICTION CENTER HAS ALREADY ISSUED A SLIGHT RISK FOR
SOUTHEASTERN WYOMING SO THIS WILL HAVE TO BE WATCHED. ONE CHANGE WE
DID MAKE WAS FOR TUESDAY NIGHT WITH THE MODELS SHOWING DRIER AIR
MOVING IN BEHIND THE SHORTWAVE AND ASSOCIATED COLD FRONT SO WE
REDUCED AND REMOVED SOME POPS...ESPECIALLY ACROSS THE WESTERN TWO
THIRDS OF THE COUNTY WARNING AREA.

.LONG TERM...WEDNESDAY THROUGH SUNDAY

ON WEDNESDAY...EMBEDDED DISTURBANCES IN NORTHWEST FLOW WILL CONTINUE
CHANCES FOR SHOWERS AND THUNDERSTORMS...HOWEVER...WITH LIMITED
INSTABILITY...THE THREAT FOR STRONG TO SEVERE STORMS IS LOW. COOL
CONDITIONS ALSO CONTINUE FOR ONE MORE DAY BEHIND TUESDAYS FRONT.
THURSDAY...A BRIEF RIDGE OF HIGH PRESSURE PUSHES ACROSS THE
REGION...RETURNING MORE NORMAL TEMPERATURES. WEAK INSTABILITY COULD
ALSO BRING A FEW ISOLATED THUNDERSTORMS...MAINLY ACROSS THE HIGHER
TERRAIN OF WESTERN AND NORTHERN WYOMING. FRIDAY AND SATURDAY...RIDGE
EXITS THE REGION AND WESTERLY FLOW WILL CONTINUE WARM TEMPERATURES
IN THE UPPER 80S TO LOW 90S ON FRIDAY. A SHORTWAVE AND ITS
ASSOCIATED COLD FRONT LOOK TO PUSH ACROSS THE REGION FRIDAY AND
SATURDAY...HOWEVER TIMING AND EXACT LOCATION ARE STILL A BIT
UNCERTAIN. GFS STILL A BIT FURTHER NORTH AND MORE PROGRESSIVE THAN
THE ECMWF. EITHER SOLUTION WILL SUPPORT AT LEAST SMALL CHANCES FOR
ISOLATED TO SCATTERED THUNDERSTORMS FRIDAY AND SATURDAY...WITH MORE
WIDESPREAD COVERAGE AND SLIGHTLY COOLER TEMPS ON SATURDAY IF THE
ECMWF PANS OUT. A LARGE RIDGE OF HIGH PRESSURE BEGINS TO DEVELOP
SUNDAY...AND WILL BRING WARM AND DRY SOUTHWEST FLOW TO END THE
WEEKEND.

&&

.AVIATION.../12Z ISSUANCE/

LIGHT WINDS WITH MAINLY SKC CONDITIONS WILL OCCUR THIS MORNING.
ISOLATED CONVECTION IS EXPECTED TO DEVELOP THIS AFTERNOON MAINLY
OVER THE MOUNTAINS...AND SHOULD DECAY RELATIVELY QUICKLY AS THEY
MOVE INTO THE LOWER ELEVATIONS. WEAK FORCING AND INSTABILITY WILL
LIMIT COVERAGE OF SHOWERS...LET ALONE TS. THUS WILL NOT MENTION TS
AT ANY TAF SITE AND LIMIT VCSH TO THOSE TERMINALS NEAR MOUNTAINS.
THE MAIN HAZARD TODAY WILL BE GUSTY OUTFLOW WINDS. THE CONVECTION
OUTFLOW WINDS COULD IMPACT TERMINALS THAT DO NOT HAVE VCSH
MENTIONED. ANY CONVECTION SHOULD QUICKLY WANE THIS EVENING WITH VERY
LITTLE OR NO CONVECTION LEFT BY 03Z. WIND FIELDS WILL BE LIGHT AND
MAINLY NORTHERLY TODAY. THE EXCEPTION OF COURSE WILL BE WINDS
PRODUCED BY CONVECTION.

&&

.FIRE WEATHER...

EXPECT ANOTHER ROUND OF ISOLATED TO WIDELY SCATTERED SHOWERS AND
THUNDERSTORMS ACROSS MUCH OF THE AREA THIS AFTERNOON AND EVENING.
THE BEST COVERAGE WILL BE ACROSS THE MOUNTAINS WITH THE LEAST
COVERING ACROSS SOUTHWESTERN WYOMING. WE SHIFT TO A NORTHWEST FLOW
PATTERN BY MONDAY WITH A COLD FRONT POSSIBLY DROPPING SOUTHWEST INTO
THE DIVIDE DURING THE DAY...AND BEYOND OVERNIGHT. THIS COULD BE THE
FOCUS OF ANOTHER ROUND OF WET SHOWERS AND THUNDERSTORMS ESPECIALLY
ALONG AND EAST OF THE DIVIDE. ANOTHER WAVE OF SHOWERS AND STORMS IS
POSSIBLE ON TUESDAY. RELATIVE HUMIDITY AND WINDS ARE NOT EXPECTED TO
REACH CRITICAL LEVELS FOR THE NEXT FEW DAYS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...HATTINGS
LONG TERM...ANGLIN/WM
AVIATION...WM
FIRE WEATHER...HATTINGS








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