Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 301830
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1230 PM MDT TUE SEP 30 2014

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT

PREVIOUS FORECAST LOOKS TO BE ON TRACK...MOST OF THE ACTIVITY WILL
BE EAST OF THE AREA TODAY AS WE TRANSITION TO MOIST WESTERLY FLOW.
RAPID LEE CYCLOGENESIS IS ALREADY BEGINNING NEAR THE NE/WY/SD TRIPLE
POINT...WHICH WILL TRANSLATE TO A NOTICEABLE INCREASE IN WESTERLY
WINDS ACROSS THE FORECAST AREA... ESPECIALLY ACROSS THE SOUTH EARLY.
THE LOW WILL MOVE NORTH AND EAST DURING THE MORNING...SWITCHING
WINDS TO THE NORTHWEST ACROSS OUR NORTHERN HALF OF THE FORECAST
AREA...AND ENCOURAGING A COLD FRONT TO DIP SOUTH...WHICH COULD LEAD
TO GUSTS OVER 40 MPH WINDS IN NORTHERN JOHNSON COUNTY IF EVERYTHING
LINES UP RIGHT. ASIDE FROM THE WIND...OROGRAPHIC LIFT ACROSS THE
WEST...A COLD FRONT DIPPING INTO THE NORTH...AND A DEFORMATION AXIS
POKING INTO OUR EASTERN ZONES COULD KEEP SOME MORE PERSISTENT RAIN
GOING IN THESE AREAS...WITH SNOW ABOVE 8500FT IN THE WESTERN
MOUNTAINS AND YELLOWSTONE. IT WILL BE VERY WEAKLY UNSTABLE
ELSEWHERE...AND THAT COMBINED WITH DECENT RESIDUAL MOISTURE COULD
ALLOW FOR SOME ISOLATED AFTERNOON SHOWERS IN BETWEEN. IT WILL
DEFINITELY STILL BE A COOL...MOIST AND RAW DAY FOR MUCH OF THE AREA.

INTO WEDNESDAY...A REINFORCING SHOT COULD ARRIVE IN THE WESTERLY
FLOW...WITH YET ANOTHER WEATHER SYSTEM FOR WEDNESDAY KEEPING SHOWERS
IN THE FORECAST AND DIPPING SNOW LEVELS DOWN BELOW 7000FT ACROSS THE
WEST AND NORTH. THESE NEXT COUPLE OF SYSTEMS ARE NOT EXPECTED TO
AMOUNT TO MUCH PRECIPITATION BUT THEY HAVE A BETTER SHOT AT LAYING
DOWN A WETTING RAIN AND A MOUNTAIN SNOW ACROSS THE NORTH...BASICALLY
THE ONLY AREA IN OUR CWA THAT DID NOT GET MUCH OUT OF THE WEEKEND
STORM. COULD SEE A DECENT QUARTER TO HALF INCH OF PCPN IN THE NW
MOUNTAINS WITH 2 TO 4 INCHES OF SNOW ABOVE 9K...MAYBE AN INCH OR TWO
DOWN TO AS LOW AS 7-8K AND A BRIEF CHANGEOVER DOWN TO AS LOW AS 6K
IN THE CODY FOOTHILLS EARLY WEDNESDAY MORNING. OUR LAST WAVE SHOULD
EXIT WEDNESDAY EVENING LEAVING BEHIND A VERY COOL AND FROSTY NIGHT
FOR MUCH OF THE FORECAST AREA.

THE NEXT APPROACHING SHORTWAVE FOR THURSDAY LOOKS TO BE A GLANCING
BLOW WITH JUST A SLIGHT CHANCE OF RAIN IN THE FAR NRN/ERN ZONES
THURSDAY WITH GUSTY NORTH WINDS AND CLOUDS. COULD ALSO SEE SOME
GUSTY WINDS IN THE CODY FOOTHILLS WEDNESDAY NIGHT INTO THURSDAY
MORNING AHEAD OF THIS SYSTEM. ELSEWHERE...IT WILL BE MAINLY DRY AND
REMAINING COOL WITH SWIFT NORTHWEST FLOW ALOFT TRANSLATING TO A FEW
20 TO 35 MPH BREEZES DEVELOPING ACROSS THE SOUTH.

.LONG TERM...FRIDAY THROUGH TUESDAY

THE LONG RANGE MODELS ARE IN GOOD AGREEMENT THROUGH SUNDAY WITH THE
WEATHER PATTERN. ON MONDAY AND TUESDAY THE GFS AND GEM MODELS TRY TO
SAG A COLD FRONT ALONG THE MONTANA/WY BORDER WITH PRECIP GETTING
CLOSE MONDAY NIGHT AND TUESDAY ALONG THE BORDER. THE ECMWF IS
DIFFERENT EARLY NEXT WEEK AND KEEPS THE COOLER AIR IN SOUTHERN
CANADA/NORTHERN MONTANA AND DRY WEATHER ALONG THE NORTHERN WY
BORDER. FOR NOW WILL COMPROMISE AND KEEP THE FORECAST DRY AND KNOCK
A DEGREE OR TWO OFF THE HIGH TEMPS IN THE FAR NORTH MONDAY AND
TUESDAY. THERE WILL BE PERIODS OF MID AND HIGH CLOUDS MOVING THROUGH
THE AREA FRIDAY THROUGH TUESDAY WITH LIMITED AMOUNTS OF CUMULUS
CLOUDS. HIGH TEMPS WILL BE SEASONAL TO SLIGHTLY ABOVE NORMAL FRIDAY
THROUGH NEXT TUESDAY. EXPECT BREEZY AREAS IN THE AFTERNOON THROUGH
SUNSET OVER THE WEEKEND INTO EARLY NEXT WEEK. BOTTOM LINE...GOOD
FALL WEATHER FOR SEEING FALL FOLIAGE OR OTHER OUTDOOR ACTIVITIES.

&

.AVIATION.../18Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

A NEW WEATHER SYSTEM WILL PUSH A COLD FRONT SOUTH ACROSS THE AREA
OVERNIGHT INTO WEDNESDAY MORNING WITH LOWERING CEILINGS BEHIND THE
FRONT. WIDESPREAD SHOWERS ARE LIKELY IN AND NEAR THE MOUNTAINS
WITH WIDELY SCATTERED TO SCATTERED SHOWERS IN THE SOUTH. ISOLATED
THUNDERSTORMS ARE POSSIBLE. RAIN WILL LIKELY CHANGE TO SNOW IN THE
CODY FOOTHILLS BY SUNRISE. MVFR CONDITIONS WITH MOUNTAIN AND
HIGHER TERRAIN OBSCURATION WILL INCREASE BEHIND THE COLD FRONT...
ESPECIALLY AROUND KCOD BUT AREAS OF MVFR CONDITIONS WILL OCCUR
ACROSS THE SOUTH TONIGHT AND WEDNESDAY AND WILL DEVELOP BEHIND THE
COLD FRONT SLIDING SOUTH.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

WIDESPREAD RAIN SHOWERS CAN BE EXPECTED INTO THE EARLY EVENING
ACROSS THE VALLEYS WITH OCCASIONAL MOUNTAIN SNOW AND WIDESPREAD
MOUNTAIN AND FOOTHILL OBSCURATION. LOW VFR TO OCNL MVFR WILL
PREVAIL. A NEW STORM SYSTEM WILL BRING WIDESPREAD SNOW TO THE FAR
NORTHWEST OVERNIGHT AND THEN SPREAD INTO THE SOUTHWEST DURING THE
DAY WEDNESDAY. CONSIDERABLE MOUNTAIN OBSCURATION WILL CONTINUE WITH
MVFR CONDITIONS AT TIMES AND LOCALIZED IFR DURING MODERATE TO
HEAVY SNOW SHOWERS.

&

.FIRE WEATHER...

WETTING RAIN POSSIBLE ACROSS WESTERN AND CENTRAL WYOMING AGAIN
TODAY...THOUGH NOT AS MUCH AS THERE WAS THIS WEEKEND. SHOWERS WILL
BE MORE SCATTERED TODAY ACROSS THE NORTH...WEST AND EAST WITH
ISOLATED SHOWERS AND A THUNDERSTORM OR TWO ACROSS THE SOUTH. IT WILL
REMAIN COOL AND CLOUDY THROUGH THURSDAY AS A SERIES OF DISTURBANCES
AND COLD FRONTS MOVE THROUGH THE REGION. IT WILL BE WARMER AND DRIER
ON FRIDAY WITH SWIFT WEST TO NORTHWEST FLOW CONTINUING.

&&

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

&&

$$

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










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