Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 281938
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
138 PM MDT SUN JUN 28 2015

.SHORT TERM...TONIGHT THROUGH MONDAY

WV IMAGERY SHOWS LARGE AMPLIFIED BUBBLE HIGH OVR THE WRN CONUS WITH
EMBEDDED DISTURBANCES AND BITS OF MID/UPR MOISTURE ROTATING AROUND
THE HIGH. SMALL EMBEDDED SW JUST NOW ENTERING THE NWRN FA. UPSTREAM
AND OFF THE WCST...SW TROF W OF NRN CALIFORNIA. AMPLIFIED TROF ERN
CONUS. H7 TEMPS RANGE FROM 13 TO 18 DEG C FROM E TO W. SFC HAS WY
UNDER MOSTLY HIGH P...WITH A WEAK HEAT LOW CENTERED OVR THE CNTRL
AND NRN BASINS...AND A WEAK SFC BOUNDARY/FRONT FROM ERN ID AND
ACROSS SRN MT.

OVERALL...PERHAPS THE BIGGEST THREAT THRU THE FCST WILL BE THE
POSSIBILITY OF AN ISOLATED LIGHTNING INDUCED FIRE START IN THE
MOUNTAINS.

TODAY/TONIGHT...STABLE ATMOSPHERE TO 600MB OR HIGHER. MOST CI WILL
START IN THE HEAT OF THE DAY OVR THE HIGHER MOUNTAIN PEAKS THIS
AFTERNOON...HAVING A HARD TIME MOVING OFF THE MOUNTAINS...WITH
PERHAPS A LITTLE BETTER CHANCE LATER THIS EVENING AS THE NRN
BOUNDARY/FRONT PUSHES SWD. TERRAIN FORCED CONVERGENCE IN SHALLOW
RELATIVELY MOIST NORTH FLOW AROUND THE BIGHORNS MAY BE SUFFICIENT TO
ALLOW A COUPLE OF STORMS TO PROPAGATE FROM WRN NATRONA COUNTY...SEWD
THIS EVENING. INVERTED V SOUNDINGS WITH WEAK FLOW THRU DEPTH WILL
OFFER UP MAINLY GUST BUSTER STORMS WITH LIGHTNING AND GUSTY OUTFLOW
TO 45KTS OR SO. AN ISOLATED SEVERE GUST WOULD NOT BE OUT OF THE
QUESTION.

MONDAY...POSSIBLY THE HOTTEST DAY OF THE WEEK WITH HIGH TEMPS AT OR
SLIGHTLY ABOVE 100 IN THE BIGHORN BASIN...90S OVR MOST OTHER LOWER
ELEVATIONS AND EVEN INTO THE 80S FOR SOME MOUNTAIN LOCATIONS.
OTHERWISE...WEAKER FLOW ALOFT...CAPPING MUCH DEEPER THAN
SUNDAY...AND WITHOUT ANY ADDITIONAL FORCING...FEWER THUNDERSTORMS
SHOULD PRESENT THEMSELVES. AGAIN...ANY THAT DO WILL BE TIED TO
MOUNTAINS AND BE WITHOUT MUCH PRECIPITATION.

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY

MONDAY NIGHT LOOKS TO BE WARM AND GENERALLY DRY.

GREAT BASIN UPPER LEVEL RIDGE BEGINS TO BREAK DOWN BY TUESDAY WITH
COOLER AIR SPREADING INTO WYOMING BOTH AT THE SURFACE AND ALOFT.
REGARDLESS...NORTHWEST FLOW SETS UP ALOFT FOR THE REST OF THE WEEK.
THIS PATTERN SHOULD ALLOW A FEW COLD FRONTS TO MOVE ACROSS MOST OF
THE FORECAST AREA. DIFFICULT TO PINPOINT BOTH THE FRONTS AND ANY
SHORTWAVES ALOFT...ESPECIALLY WEDNESDAY AND BEYOND.

MEDIUM RANGE MODELS DO HINT AT MORE INSTABILITY AND ACTIVE WEATHER
TUESDAY AFTERNOON AND EVENING. AFTER TUESDAY...COULD BE THE TYPICAL
ISOLATED TO WIDELY SCATTERED AFTERNOON AND EVENING THUNDERSTORMS FOR
BOTH MOUNTAINS AND BASINS. TEMPERATURES SHOULD BE AROUND NORMAL
THROUGH THE EXTENDED PERIOD.

&&

.AVIATION.../00Z ISSUANCE/

VFR CONDITIONS WILL PREVAIL AT ALL TERMINAL SITES THROUGH THE
FORECAST. THE GREATEST THREAT TODAY WILL REVOLVE AROUND HIGH BASED
MAINLY MOUNTAIN THUNDERSTORMS THAT WILL PUT OUT FREQUENT LIGHTNING
AND GUSTY OUTFLOW WINDS IN EXCESS OF 35 MPH WELL AWAY FROM THE STORM
ITSELF. QUIET OVERNIGHT...WITH FEWER CHANCES FOR ISOLATED
THUNDERSTORMS MONDAY AFTERNOON.

&&

.FIRE WEATHER...

FIRE DANGER WILL REMAIN BELOW CRITICAL AS WINDS WILL BE RELATIVELY
LIGHT AND AND FUELS REMAIN IN GREEN-UP. HOWEVER...FIRE DANGER WILL
BE ENHANCED BOTH TODAY AND TOMORROW ACROSS THE SOUTHERN HALF OF THE
FORECAST AREA AS HOT DAY TIME TEMPERATURES CONTINUE WITH MINIMUM RH
VALUES IN THE MID AND UPPER TEENS. WINDS WILL ALSO OCCASIONALLY GUST
GREATER THAN 25 MPH FOR SHORT PERIODS NEAR HIGH BASED
THUNDERSTORMS...MAINLY IN AND ADJACENT TO THE MOUNTAINS THROUGH THE
EARLY EVENING. NOT MUCH IN THE WAY OF MEASURABLE PRECIPITATION IS
EXPECTED FROM ANY STORMS THAT DO FORM TODAY OR MONDAY.

&&

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

$$

SHORT TERM...BRAUN
LONG TERM...KPL
AVIATION...BRAUN
FIRE WEATHER...BRAUN



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