Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 090911
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
311 AM MDT WED APR 9 2014

.SHORT TERM...WEDNESDAY THROUGH FRIDAY NIGHT

THINGS LOOK FAIRLY UNEVENTFUL THIS MORNING. THE POSSIBLE EXCEPTION
WILL BE NEAR THE CODY FOOTHILLS WHERE THERE COULD BE SOME NEAR
WARNING GUSTS OF WIND...MAINLY AROUND CLARK. HOWEVER...SINCE THERE
IS A NAME FOR THAT IN CLARK...WEDNESDAY...WE WILL NOT ISSUE ANY HIGH
WIND HIGHLIGHTS. THINGS DO LOOK TO GET A BIT MORE ACTIVE THIS
AFTERNOON AS A COLD FRONT AND ASSOCIATED UPPER LEVEL DISTURBANCE
DROP SOUTHWARD OUT OF MONTANA AND INTO NORTHERN WYOMING THIS
AFTERNOON AND EVENING. ACROSS NORTHERN WYOMING...LIFTED INDICES DO
DROP DOWN AS LOW AS MINUS 3 AND WITH A BIT OF CAPE THERE WILL BE A
FEW SHOWERS AND THUNDERSTORMS AROUND. HOWEVER...AT THIS TIME
COVERAGE DOES NOT LOOK TO BE WIDESPREAD DUE TO LIMITED MOISTURE
AVAILABILITY. HOWEVER...WITH THE INVERTED V SOUNDINGS ANY STORM
COULD HAVE SOME STRONG WIND GUSTS. THE COVERAGE OF THE STORMS IN
CONTINUITY LOOKED REASONABLE SO WE MADE FEW CHANGES. ELSEWHERE...THE
MAIN STORY WILL BE WIND AS THE PRESSURE GRADIENT TIGHTENS AHEAD OF
THE FRONT. THINGS WILL GET BLUSTERY ACROSS MOST OF THE AREA.
HOWEVER...AGAIN THINGS LOOK TO STAY SUB WARNING AS 700 MILLIBAR
WINDS DO NOT QUITE SUPPORT HIGH WIND HIGHLIGHTS. THERE COULD BE A
STRAY GUST TO 60 MPH IN A PLACE LIKE FALES ROCK...BUT SINCE THERE IS
NOTHING THERE BUT RATTLESNAKES AND DEER...IMPACTS WOULD BE MINIMAL.
WITH THE DOWNSLOPING FLOW EXPECT ANOTHER DAY OF ABOVE NORMAL
TEMPERATURES WITH SOME LOCATIONS CRACKING 70 FOR HIGH TEMPERATURES.

THIS FRONT WILL WASH OUT LATER TONIGHT WITH ANY PRECIPITATION
FADING. ANOTHER SHORTWAVE WILL CROSS THE STATE TOMORROW.
HOWEVER...AGAIN WITH VERY LIMITED MOISTURE WE HAVE KEPT POPS MAINLY
IN THE SILENT CATEGORY FOR MOST LOCATIONS. ONE WRINKLE IS THAT THE
18Z NAM DID HAVE SOME CONVECTION OVER THE AREA. HOWEVER THE 18Z RUNS
OF MODELS ARE NOTORIOUSLY UNRELIABLE AND THE MODEL NOW HAS LITTLE
PRECIPITATION. TEMPERATURES WILL COOL SOMEWHAT ON THURSDAY BUT STILL
REMAIN ABOVE NORMAL. AS WELL...WINDS WILL DECREASE SOMEWHAT BUT
BREEZY CONDITIONS WILL STILL BE COMMON ACROSS MANY AREAS.

BY FRIDAY FLAT RIDGING ACROSS THE STATE WILL BRING ANOTHER DRY AND
MILD DAY WITH GUSTY BREEZES ACROSS THE FAVORED LOCATIONS ONCE AGAIN.
THE NEXT WEATHER MAKER IN THE FORM OF A COLD FRONT WILL DROP
SOUTHWARD FROM MONTANA ON FRIDAY NIGHT...BUT ANY EFFECTS OF THIS
SHOULD HOLD OFF FOR MOST AREAS UNTIL SATURDAY. MY ESTEEMED COLLEAGUE
WILL HAVE MORE ON THIS IN THE LONG RANGE PORTION OF THE DISCUSSION.

.LONG TERM...SATURDAY THROUGH WEDNESDAY

GLOBAL MODELS CONTINUE TO INDICATE THE POTENTIAL FOR A SPRING SNOW
STORM ALONG AND EAST OF THE DIVIDE THIS WEEKEND. A COLD FRONT SHOULD
BE ACROSS EXTREME NORTHERN WYOMING BY 12Z SATURDAY...ASSOCIATED WITH
AN INITIAL SHORTWAVE OVER SOUTHERN MONTANA EARLY SATURDAY QUICKLY
PULLING INTO THE NORTHERN PLAINS. ON THE HEELS OF THIS FIRST
SYSTEM...THERE WILL BE A STRONGER SHORTWAVE TROUGH IN THE NORTHWEST
FLOW DIGGING INTO THE NORTHERN INTERMOUNTAIN WEST SATURDAY. THIS
WILL PUSH THE COLD FRONT SOUTH...REACHING THE CONTINENTAL DIVIDE
BY ABOUT 00Z SUNDAY. BY 00Z...GLOBAL MODELS SHOW A STRONG
BAROCLINIC ZONE SETTING UP ALONG THE DIVIDE...WITH THE POSSIBILITY
OF A MID LEVEL CIRCULATION AT 700MB PUSHING SOUTHEAST ALONG THE
DIVIDE INTO SOUTHERN WYOMING SATURDAY NIGHT...WHILE THE MAIN
ENERGY AT 500 MB PUSHES ACROSS SE ID/SW WY/N UT AREA.
PRECIPITATION WILL BE INCREASING ACROSS NORTHERN WYOMING
SATURDAY...ESPECIALLY IN THE AFTERNOON WITH APPROACH OF THE
STRONGER SYSTEM. PRECIPITATION TYPE DURING THE DAY SATURDAY IS
EXPECTED TO MAINLY MOUNTAIN SNOW AND VALLEY RAIN. HOWEVER...RAIN
IN THE LOWER ELEVATIONS SHOULD QUICKLY CHANGE TO SNOW LATE
SATURDAY AFTERNOON INTO SATURDAY EVENING FROM NORTH TO SOUTH...AS
COLDER AIR WORKS INTO THE AREA. ALSO...PRECIPITATION IS EXPECTED
TO INCREASE IN COVERAGE AND INTENSITY SATURDAY EVENING AND LAST
THROUGH THE NIGHT...ESPECIALLY ALONG AND EAST OF THE DIVIDE. THIS
TROUGH IS THEN EXPECTED TO GRADUALLY EXIT THE AREA SUNDAY INTO
SUNDAY EVENING WITH THE 00Z GFS THE QUICKEST TO DRY THINGS OUT.
HAVE INCREASED POPS ACROSS CENTRAL AND SOUTHERN SECTIONS
ESPECIALLY FOR SUNDAY MORNING AS SOME SNOWFALL WILL LIKELY BE
ONGOING. THE 500MB TRACK OF THE TROUGH SATURDAY NIGHT MENTIONED
ABOVE WOULD FAVOR LANDER FOR THE BEST SHOT AT SIGNIFICANT
SNOWFALL...BUT FOR A STORM STILL 4.5 DAYS OUT...A LOT STILL COULD
CHANGE.

A TRANSITORY RIDGE WITH MAINLY DRY AND WARMER CONDITIONS WILL OCCUR
MONDAY. HOWEVER THIS WILL BE SHORT LIVED AS MODELS ARE SHOWING THE
POSSIBILITY OF ANOTHER STORM SYSTEM POSSIBLY IMPACTING THE AREA
TUESDAY AND WEDNESDAY. DUE TO THE UNCERTAINTY IN THE MODELS WILL
BROAD BRUSH MAINLY CHANCE MTN/SLIGHT VALLEY POPS FOR TUESDAY AND
WEDNESDAY.

TEMPERATURES WILL BE TRICKY SATURDAY WITH A COLD FRONT SLIDING
SOUTH...BUT MANY AREAS WILL BE SEASONAL EAST OF THE DIVIDE AND ABOVE
AVERAGE WEST. HIGH TEMPERATURES SUNDAY SHOULD BE 10 TO 20 DEGREES
BELOW AVERAGE...AND HAVE GONE 5-10 DEGREES BELOW MEX MOS GUIDANCE.
TEMPERATURES REBOUND TO SEASONAL LEVELS MONDAY.

&&

.AVIATION.../12Z ISSUANCE/

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

VFR CONDITIONS WILL OCCUR AT THE TERMINAL SITES TODAY AND TONIGHT.
GUSTY WIND WILL OCCUR AT MOST SITES AFTER 18Z UNTIL 02Z. SCATTERED
RAIN SHOWERS WITH HIGH ELEVATION SNOW SHOWERS WILL OCCUR BETWEEN 21Z
AND 05Z AS A COLD FRONT MOVES THROUGH THE REGION THIS EVENING. A FEW
THUNDERSTORMS MAY ALSO OCCUR. LOCAL MVFR CONDITIONS ARE POSSIBLE IN
THE NORTHWEST WY MOUNTAINS FROM 21Z UNTIL 05Z.

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

VFR CONDITIONS WILL OCCUR AT THE TERMINAL SITES TODAY AND TONIGHT. A
GUSTY WIND WILL OCCUR AT MOST TERMINAL SITES AFTER 17Z THROUGH 01Z.
A COLD FRONT WILL PUSH INTO NORTHERN WY BY 22Z WITH A WIND SHIFT TO
THE NORTH. THIS FRONT WILL PUSH SOUTH INTO CENTRAL WY AFTER 01Z WITH
A NORTH WIND DEVELOPING. SCATTERED RAIN SHOWERS WILL OCCUR OVER THE
NORTH AFTER 22Z AND CONTINUE THROUGH 06Z. A FEW THUNDERSTORMS MAY
ALSO OCCUR OVER THE NORTH LATE IN THE AFTERNOON AND EVENING. A FEW
RAIN SHOWERS MAY OCCUR AROUND KCPR AFTER 03Z UNTIL 08Z THURSDAY.

&&

.FIRE WEATHER...

HIGH PRESSURE WILL BRING DRY CONDITIONS ACROSS THE AREA THROUGH
MIDDAY WEDNESDAY. BREEZY CONDITIONS MAY DEVELOP LATER TODAY FROM THE
RED DESERT THROUGH NATRONA COUNTY. WIND WILL INCREASE EAST OF THE
ABSAROKAS TONIGHT ACROSS MUCH OF THE AREA LATE TONIGHT AND TOMORROW
AS A COLD FRONT AND ASSOCIATED UPPER LEVEL DISTURBANCE APPROACH.
THIS FRONT MAY BRING SOME SHOWERS AND THUNDERSTORMS WEDNESDAY
AFTERNOON INTO WEDNESDAY EVENING FROM THE OWL CREEK AND BRIDGER
RANGE AND NORTHWARD. QUIETER AND SOMEWHAT COOLER WEATHER WILL RETURN
FOR THURSDAY. EXPECT WARMER AND BREEZY WEATHER FOR FRIDAY.

&&

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

&&

$$

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







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