Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 220938
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
338 AM MDT TUE JUL 22 2014

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT

ONCE AGAIN MOTHER NATURE AS DECIDED TO THROW A CURVEBALL AT THE
FORECAST THIS EVENING. SINCE AROUND 11 PM SOME THUNDERSTORMS HAVE
FIRED ALONG A BOUNDARY FROM NORTH OF ROCK SPRINGS TO WEST OF
CASPER...MORE THAN LIKELY ALONG AN OLD OUTFLOW BOUNDARY THAT MOVED
THROUGH SOME AREAS THIS EVENING. THESE THUNDERSTORMS ENDED AT 3 AM.

AS FOR TODAY...HEIGHTS WILL CONTINUE TO BUILD ACROSS THE STATE
HAS A RIDGE OF HIGH PRESSURE OVER COLORADO CONTINUES TO
STRENGTHEN. THIS SHOULD HELP TO SUPPRESS CONVECTION A BIT MORE
THAN ON MONDAY. IN ADDITION...PRECIPITABLE WATER VALUES OF UNDER
0.50 INCHES WILL MOVE OVER APPROXIMATELY THE SOUTHWESTERN HALF OF
THE AREA. HOWEVER...THERE IS STILL SOME MOISTURE NORTH OF THIS
LINE. SO WE ARE A LITTLE LEARY TO TAKE OUT POPS COMPLETELY. WE
MADE FEW CHANGES AT THIS TIME WITH KEEPING SOME ISOLATED POPS
ACROSS NORTHERN PORTIONS OF THE COUNTY WARNING AREA WITH THE RING
OF FIRE. TEMPERATURES MAY COOL A DEGREE OR TWO TODAY BUT THE
DIFFERENCE WILL LIKELY NOT BE NOTICEABLE. ONE CHANGE IS THAT
HUMIDITY WILL BE A BIT HIGHER AND THERE WILL BE LESS WIND TODAY
WITH LESS OF A PRESSURE GRADIENT. AS A RESULT...FIRE CONDITIONS
WILL IMPROVE AND NO RED FLAG WARNINGS WILL BE ISSUED THIS MORNING.
ANY THUNDERSTORMS SHOULD END THIS EVENING WITH MAINLY QUIET
WEATHER FOR LATE TUESDAY NIGHT AND INTO WEDNESDAY.

THE MODELS CONTINUE TO HAVE SOME AGREEMENTS AND DISAGREEMENTS OVER
BOTH WEDNESDAY AND THURSDAY. AS FOR THE AGREEMENTS...WITH
THICKNESSES RISING IT WILL TURN VERY HOT ACROSS THE AREA WITH LOWER
ELEVATIONS SEEING HIGH TEMPERATURES WELL INTO THE 90S FOR WEDNESDAY
AND THURSDAY. SOME OF THE HOTTER AREAS LIKE THE EASTERN BIG HORN
BASIN MAY SEE SOME TRIPLE DIGIT HIGH TEMPERATURES. ALSO...THE MODELS
SHOW DRIER AIR WORKING INTO THE WESTERN HALF OF THE COUNTY WARNING
AREA SO THE CHANCE OF ANY SHOWER OR THUNDERSTORM ACTIVITY WILL
DWINDLE TO ALMOST NOTHING IN THAT VICINITY BY THURSDAY. IN
ADDITION...GUSTY BREEZES WILL DEVELOP ONCE AGAIN THAT WILL LIKELY
ONCE AGAIN INCREASE FIRE DANGER ACROSS MUCH OF THE AREA. AS FOR THE
DISAGREEMENTS...THE MAIN ONE FOR THE EASTERN HALF OF THE COUNTY
WARNING AREA IS THE POTENTIAL FOR THUNDERSTORMS. THE NAM IS THE
WETTER MODEL AT THIS POINT IN BRINGING PRECIPITABLE WATERS OF OVER
AN INCH IN SOME LOCATIONS TO AREAS EAST OF THE BIGHORNS...ESPECIALLY
ON WEDNESDAY. MEANWHILE...THE GFS CONTINUES TO PRESS DRIER AIR
ACROSS THE ENTIRE AREA WITH LITTLE OR NO CHANCE FOR CONVECTION. AS A
COMPROMISE WE ADDED SOME SLIGHT POPS TO EXTREME EASTERN AREAS.
HOWEVER...CONFIDENCE IS LOW AT THIS POINT.

.LONG TERM...FRIDAY THROUGH TUESDAY

A DRY WEST FLOW ALOFT FOR FRIDAY. A COLD FRONT BOUNDARY WILL LIE
ACROSS THE CENTRAL ZONES EAST OF THE DIVIDE...BUT WILL MIX OUT
FRIDAY AFTERNOON AND THUS ONLY MINOR COOLING OF HIGHS THERE. THE
SOUTH WILL STAY VERY WARM TO HOT. BREEZY AREAS FRIDAY WILL LEAD TO
FIRE WEATHER CONCERNS CENTRAL AND SOUTH. SATURDAY THE FLOW STAYS
WEST NORTHWEST WITH DRY CONDITIONS. HIGH TEMPS REMAIN LITTLE CHANGED
FROM FRIDAY READINGS. AFTERNOON BREEZES IN THE SOUTH AND SOUTHWEST
WILL IMPACT FIRE WEATHER CONCERNS AGAIN AS EACH DAY OF THIS DRIES
OUT THE VEGETATION. ON SUNDAY THE FLOW ALOFT BENDS TO THE NORTHWEST
AS A TROUGH FORMS IN THE MIDWEST AND THE UPPER RIDGE NUDGES INTO THE
GREAT BASIN AND SOUTHWEST STATES. A LITTLE COOLER AIR GETS PUSHED
INTO EASTERN WY AND MAY GET BACK TO THE CONTINENTAL DIVIDE. 700MB
TEMPS ALSO COOL A BIT EAST OF THE DIVIDE. THIS WOULD RESULT IN
SLIGHT COOLING EAST OF THE DIVIDE. OUT WEST THE BUBBLE OF WARMER AIR
RESIDES AND A FEW DEGREES WARMER FOR HIGHS ON SUNDAY. MONDAY AND
TUESDAY FIND THE UPPER RIDGE BUILDING OVER THE WESTERN U.S. AND THE
TROUGH DEEPENING OVER THE GREAT LAKES AND MIDWEST. THIS PUTS WY IN
THE MIDDLE GROUND. MID AND HIGH LEVEL MOISTURE DOES GRADUALLY GET
PULLED AROUND THE RIDGE AND INTO WY MON AND TUE. EVEN A FEW WEATHER
DISTURBANCES ARE NOTED ON THE GFS AND ECMWF MODELS ROTATING INTO THE
REGION. OF COURSE TIMING THAT FAR OUT CAN BE DIFFICULT. FOR NOW WILL
PLAY ISOLATED MAINLY MOUNTAIN STORMS OR SHOWERS MONDAY PM AND NIGHT
AND THEN A LITTLE HIGHER CHANCE ON TUE PM INTO TUE NIGHT. A TAD
WARMER ON MONDAY AND THEN LITTLE CHANGE IN HIGHS NEXT TUE AS MORE
CLOUDS MAY RESULT IN SLIGHT COOLING IN SOME LOCATIONS.

&&

.AVIATION.../12Z ISSUANCE/

A DRIER AIR MASS WILL PUSH NORTH ACROSS THE FORECAST AREA...WHICH
SHOULD LIMIT ISOLATED CONVECTION TO THE HIGHER TERRAIN OVER THE
NORTH. COVERAGE WILL BE TOO LIMITED TO MENTION AT ANY TERMINAL AT
THIS TIME. WINDS ARE EXPECTED TO BE MAINLY LIGHT.

&&

.FIRE WEATHER...

FIRE CONDITIONS SHOULD IMPROVE TODAY AS WINDS WILL SUBSIDE AND
RELATIVE HUMIDITIES RISE A BIT. SHOWERS AND THUNDERSTORMS SHOULD BE
MORE LIMITED THAN ON MONDAY AND CONFINED TO NORTHERN WYOMING. A
COMBINATION OF HOT TEMPERATURES...LOW RELATIVE HUMIDITY AND THE
RETURN OF A GUSTY WEST TO SOUTHWEST WIND WILL LIKELY BRING ELEVATED
FIRE DANGER FOR WEDNESDAY AND INTO THURSDAY AS WELL.

&&

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

&&

$$

SHORT TERM...HATTINGS
LONG TERM...AR
AVIATION...WM
FIRE WEATHER...HATTINGS




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