Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 242039
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
220 PM MDT SUN AUG 24 2014

.SHORT TERM...TONIGHT THROUGH MONDAY

WV IMAGERY SHOWING UPR CLOSED LOW AND TROF NOW OFF TO THE NE AND
OVR THE NRN PLAINS...CENTERED OVR MT/ND BORDER. SFC LOW TILTED WELL
TO THE E OF THE UPR LOW AND OVR NERN ND. NRN WY STILL FEELING SOME
INFLUENCE FROM THE UPR TROF AS A SMALL VORTMAX JUST NOW PUSHES INTO
PARK COUNTY AND POINTS E...W/ CLOUD AND A FEW LIGHT SHOWERS AROUND
EARLY THIS AFTERNOON OVR THE FAR NRN ZONES. UPSTREAM...BROAD WRN
CONUS LOW IN PLACE. EMBEDDED...JUST BARELY DISCERNIBLE IN
IMAGERY...WEAK DISTURBANCE IN NCNTRL UT. A COUPLE OF STRONGER SW/JET
MAX(ES) ARE CURRENTLY RUSHING DOWN THE BACKSIDE OF THE BROAD WRN
CONUS TROF THRU CNTRL CALIFORNIA AND THEN TO THE N AND INTO NRN OR
AND WRN WA. THESE WILL EVENTUALLY (RE)DEVELOP ANOTHER DEEP/DIGGING
TROF ACROSS THE WEST.

LATE AFTERNOON AND TONIGHT...NRN UT DISTURBANCE WILL ARRIVE OVR/NEAR
THE SRN BORDER REGION OF SWEETWATER COUNTY WITH A FEW MAINLY
ISOLATED SHRA/ISO TSRA CONTINUING IN THIS AREA THROUGH THE EVENING
PERIOD. A FEW ADDITIONAL SHOWERS MAY BE FOUND LATER THIS AFTERNOON
AND EARLY EVENING WITH SOME DIURNAL/TERRAIN FORCING ACROSS THE NWRN
MOUNTAINS AS THE WAVE ASSOCIATED WITH THE SMALL VORTMAX...NOW
PUSHING THROUGH THE NW ZONES...ALIGNS ITS AXIS OVR THE NWRN
MOUNTAINS AND PROVIDES A SMALL CHANCE FOR ISOLATED TO WIDELY
SCATTERED SHOWER ACTIVITY EARLY...BECOMING MUCH MORE ISOLATED THRU
THIS EVENING.

BY MONDAY MORNING...THE THE FIRST OF THE STRONGER UPSTREAM SWS...
NOW OVR CNTRL CA...WILL BEGIN TO ARRIVE NEAR THE SWRN PORTION OF THE
FA...WITH INSTABILITY SHOWERS BREAKING OUT OVR THE SW QUARTER OF THE
FA WHILE HELPING TO DEVELOP LOW PRESSURE INTO THIS REGION AT THE
SAME TIME. THESE SHOWERS MAY MAKE IT INTO CENTRAL WY BY LATE
MORNING. THIS WILL ALSO HAVE THE EFFECT OF CREATING A BOUNDARY OVR
THE SRN TO SERN CWA DURING THE DAY WHICH MAY BECOME A FRONTAL
BOUNDARY...HAVING A FOCUS EFFECT LATER IN THE AFTERNOON CONCERNING
CI. FROM MID-DAY ON...A WRN CONUS TROF WILL HAVE REDEVELOPED WITH A
FEW UPR WAVES EJECTING OUT AHEAD OF THIS FEATURE AND INTO WY...ALONG
WITH ANOTHER BATCH OF EPAC MOISTURE. FORCING FROM ALOFT IN ADDITION
TO SOME MODEST HEATING AND THE TERRAIN ITSELF WILL ALLOW FOR SHOWERS
AND ISOLATED THUNDER TO BLOSSOM ACROSS THE WRN MOUNTAINS. THESE
SHOWERS/STORMS SHOULD BEHAVE FOR THE MOST PART...HOWEVER A COUPLE OF
STRONGER STORMS MAY BE FOUND ACROSS THE TETONS TO THE SOUTHERN
ABSAROKAS.  ADDITIONALLY...A FEW STRONGER STORMS MAY BE FOUND ALONG
AND SOUTH OF THE DEVELOPING BOUNDARY/FRONT LOCATED SOMEWHERE OVR ERN
SWEETWATER COUNTY AND LIFTING N INTO POSSIBLY ERN FREMONT AND
NATRONA COUNTIES BY LATE AFTERNOON. MORE SUNSHINE AND SOME LOW END
MOISTURE RETURN OUT OF COLORADO...WILL COMBINE TO GIVE MID-DAY CAPE
VALUES FROM BETWEEN 500 AND 1000 J/KG. WITH DEEP SHEAR OF 35 TO 40
KTS...THIS THIN AREA OVER AND AROUND THE FRONT MAY PRODUCE SOME
STRONG STORMS WITH SMALL TO MARGINAL SVR HAIL AND STRONG WIND GUSTS
FOR A SHORT PERIOD MONDAY AFTERNOON. THE FURTHER SOUTH TO SOUTHEAST
OF THE FRONT...THE STRONGER THE WIND GUSTS.

.LONG TERM...MONDAY NIGHT THROUGH SUNDAY

MONDAY NIGHT WILL SEE THE SOUTHERN STREAM OF SHORTWAVE ENERGY WIN
OUT WITH SCATTERED SHOWERS AND ISOLATED AFTERNOON AND EVENING
THUNDERSTORMS AS THE NORTHERN PORTION OF THE TROUGH MOVES EAST INTO
THE NORTHERN PLAINS.  WITH WARM AIR ADVECTION COMING UP FROM THE
GREAT BASIN...SLIGHT WARMING IS EXPECTED.

TUESDAY AND TUESDAY NIGHT A PORTION OF THE LONG WAVE TROUGH WILL
DEEPEN OVER WESTERN IDAHO WITH INCREASING ENERGY AND MOISTURE IN THE
SOUTHERN STREAM ADVECTING NORTHWEST FROM THE GREAT BASIN OVER
SOUTHERN AND WESTERN WYOMING.  ANOTHER ROUND OF SCATTERED SHOWERS
AND ISOLATED AFTERNOON AND EVENING THUNDERSTORMS IS EXPECTED WITH
CONTINUED GRADUAL WARMING.  THE WESTERN IDAHO LOW WILL TRACK EAST
THROUGH CENTRAL WYOMING LATE TUESDAY NIGHT WITH DRYING LATE.

WEDNESDAY AND WEDNESDAY NIGHT THE LOW WILL BECOME CUT OFF AND APPEARS
TO SLOW AS IT MOVES EAST ACROSS SOUTHERN WYOMING KEEPING SOME
SHOWERS AND ISOLATED THUNDERSTORMS OVER THE AREA THROUGH THE EVENING
WITH THE NORTHWEST DRYING.  A DRY HIGH PRESSURE RIDGE IS EXPECTED TO
BUILD OVER THE WESTERN U.S. WITH NORTHERLY FLOW ALOFT OVER WESTERN
AND CENTRAL WYOMING LATER WEDNESDAY NIGHT WITH CLEARING WITH WARMING
CONTINUING.

THURSDAY AND THURSDAY NIGHT  THE WESTERN U.S. HIGH PRESSURE RIDGE
ALOFT WILL BUILD NORTH AND SLOWLY MOVE EAST WITH DRY CONDITIONS WITH
NORTH TO NORTHWEST FLOW ALOFT.  WARMING IS EXPECTED TO CONTINUE.

FRIDAY AND FRIDAY NIGHT  THE HIGH PRESSURE RIDGE WILL BEGIN MOVING
EAST THROUGH THE AREA WITH SOUTHWEST FLOW ALOFT DEVELOPING FRIDAY
NIGHT AS THE RIDGE AXIS MOVES INTO THE NORTHERN AND CENTRAL HIGH
PLAINS. DRY CONDITIONS WITH CONTINUED WARMING IS EXPECTED AT LEAST
UNTIL LATE FRIDAY NIGHT WHEN CLOUDS AND ISOLATED SHOWERS WILL MOVE
INTO THE NORTHWEST.  INCREASING SOUTHWEST WINDS WILL OCCUR ACROSS
SOUTHERN AND CENTRAL AREAS.

SATURDAY AND SATURDAY NIGHT AS A PACIFIC TROUGH MOVES INTO THE
PACIFIC NORTHWEST... THE SOUTHWEST FLOW ALOFT WILL INTENSIFY WITH
INCREASING PACIFIC MOISTURE IN THE FLOW.  SHOWERS WILL INCREASE
ACROSS THE WESTERN MOUNTAINS WITH GENERALLY ISOLATED THUNDERSTORMS
EXPECTED BY AFTERNOON CONTINUING THROUGH THE EVENING WITH SOME
SHOWERS LINGERING THROUGH THE NIGHT.  SOUTHWEST WINDS WILL CONTINUE
TO INTENSIFY ACROSS SOUTHERN AND CENTRAL AREAS.  SATURDAY SHOULD SEE
THE WARMEST TEMPERATURES THROUGH THE MID AND EXTENDED FORECAST
PERIODS.

SUNDAY A PACIFIC LOW PRESSURE TROUGH WILL MOVE EAST FROM THE PACIFIC
NORTHWEST AND MOVE INTO WESTERN WYOMING THROUGH THE DAY WITH
INCREASED SHOWERS AND ISOLATED THUNDERSTORM ACTIVITY.  SOME COOLING
IS EXPECTED...ESPECIALLY IN THE WEST AND NORTH.  THE SOUTH AND EAST
WILL REMAIN BREEZY TO WINDY AHEAD OF THE TROUGH.  MODELS IN FAIR
AGREEMENT THROUGH THE EXTENDED WITH THE MAIN DIFFERENCES FROM
YESTERDAY IN THE TIMING OF THE LOW WEDNESDAY AND WEDNESDAY NIGHT
BEING SLOWER AND MORE CUT OFF TODAY. THIS LOW MAY CONTINUE TO CAUSE
TIMING AND LOCATION ISSUES INTO THE BEGINNING OF THE WEEK.

&&

.AVIATION.../00Z ISSUANCE/

LOW CIGS AND OCCASIONAL MVFR CONDITIONS HAVE MOSTLY ENDED ACROSS THE
TERMINAL FORECAST AREA TODAY. HOWEVER...KCOD WILL RETURN TO MVFR
CIGS AFTER 02Z AND WILL CARRY VCSH THROUGH 06Z...WITH MVFR CIGS
MAINTAINING THROUGH 16Z. MOUNTAIN OBSCURATION AND OCCASION MVFR
CONDITIONS WILL CONTINUE IN ISOLATED SHOWERS AND LOWER CIGS
THROUGHOUT THE PERIOD. OTHERWISE...ISOLATED SHOWERS WILL OCCUR OVER
THE FAR SOUTH ALONG THE UTAH/COLORADO BORDER UNTIL 06Z.
ELSEWHERE...VFR CONDITIONS WILL PREVAIL AT MOST TERMINAL LOCATIONS
UNTIL 12Z MONDAY. THEN A FEW NEW UPPER LEVEL DISTURBANCES WILL RIDE
INTO AND ACROSS THE AREA IN THE MORNING...KICKING OFF INCREASED
CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH THE DAY AND LOWERING
CIGS AT KPNA AND KBPI TO MARGINAL MVFR LEVEL WITH VCSH AFTER 12Z.
KJAC WILL FOLLOW SUIT AFTER 18Z. THE OTHER TERMINAL SITES SHOULD
REMAIN JUST ABOVE MVFR STATUS THROUGH THE REST OF THE FORECAST.

&&

.FIRE WEATHER...

RELATIVELY COOL LATE SUMMER TEMPERATURES WILL KEEP FIRE WEATHER
CONCERNS LOW AGAIN TODAY...REMAINING LOW THROUGH MOST OF THE WORK
WEEK AS SEVERAL DISTURBANCES ROTATE THROUGH THE REGION...KEEPING
PRECIPITATION CHANCES RELATIVELY HIGH ALONG WITH RELATIVE HUMIDITY.
THE ONLY CONCERN UNTIL NEAR THE END OF THE WEEK...WHEN THE REGION
BEGINS TO DRY OUT SOME...REVOLVES AROUND INCREASED AFTERNOON WINDS
MONDAY THROUGH WEDNESDAY...AND MAINLY ACROSS THE SOUTHERN DISPATCH
ZONES...AS THEY GUST OUT OF THE WEST TO SOUTHWEST AT 20 TO 25 MPH AT
TIMES.

&&

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

$$

SHORT TERM...BRAUN
LONG TERM...C.BAKER
AVIATION...BRAUN
FIRE WEATHER...BRAUN








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