Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 020923
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
323 AM MDT SUN AUG 2 2015

.SHORT TERM...TODAY THROUGH TUESDAY NIGHT

WV IMAGERY SHOWING STAGNANT LARGE SCALE PATTERN WITH RIDGE WRN
CONUS...TROF ERN CONUS. UPR LVL CENTER OF THIS HIGH LOCATED OVR SRN
NM WITH A STRONGER EMBEDDED WAVE OVR SFC HEAT LOW OVR AZ. SFC HAS
WEAK HIGH P ACROSS WRN WY WITH PRESSURE LOWERING TO THE NE OVR THE
NRN PLAINS.

TODAY...HOTTEST DAY OF THE PERIOD...WITH MOISTURE STARTING TO SLOWLY
WORK ITS WAY INTO THE FA FROM THE SOUTH THRU THE DAY...ALLOWING FOR
LOW CHANCE PRECIP ACROSS FAVORED HIGH MOUNTAIN RANGES LATER THIS
AFTERNOON/EVENING. HOWEVER...AS UPR WAVE CONTINUES TO SLOW A
BIT...IT DOES LOOK LIKE MOST OF THE PRECIP WILL STILL BE HELD OFF TO
THE SOUTH UNTIL MONDAY AS UPR RIDGE AXIS ROTATES CLOCKWISE...WITH
AXIS CENTERING OVR WY WHILE BETTER MONSOONAL-LIKE MOISTURE FEEDS
ACROSS WY ACCOMPANYING WHAT WAS THE AZ DISTURBANCE/NOW MCV MENTIONED
ABOVE. PWS WILL BE HIGHER THAN NORMAL...APPROACHING AN INCH IN SOME
LOCATIONS...WHILE STORM MOTION WILL BE VARIABLE AROUND THE
DEVELOPING MCV...SOME SLOW MOVING SHOWERS/STORMS THAT COME AND GO
AND SOME FASTER MOVING SHOWERS/STORMS THAT MAY TRAIN FROM SE TO NW
OVR THE WIND RIVER MOUNTAINS. MOST FORCING FOR MONDAY DAY AND NIGHT
WILL COME FROM THIS FEATURE ACROSS WRN AND CNTRL WY...WHILE TUESDAY
WILL ADD A DEVELOPING SFC LEE CYCLONE INTO THE MIX...HELPING TO
INCREASE MOISTURE AND FORCING ACROSS NRN AND NERN WY THRU THE END OF
THE FCST PERIOD. TAKE ALL THESE CONDITIONS TOGETHER...AND THERE WILL
SOME A POSSIBILITY FOR ISOLATED AREAS OF FLASH FLOODING BETWEEN
MONDAY EVENING AND TUESDAY EVENING. HARD TO LOCATE SPECIFIC
LOCATIONS ATTM...HOWEVER AREAS ALONG AND SOUTH OF THE WIND RIVER
MOUNTAINS AND LATE MONDAY...AND IN AND AROUND THE BIGHORN MOUNTAINS
AS THE SFC LOW SPINS UP OVR ERN WY BY LATER TUESDAY AFTERNOON LOOK
TO BE THE MOST SUSCEPTIBLE. ADDITIONALLY...MONDAY AFTERNOON THE ERN
ZONES MAY SEE A BRIEF PERIOD OF ISOLATED STRONGER STORMS WITH GUSTY
STRONG WINDS AND SMALL HAIL POSSIBLE ALONG WITH BRIEF HEAVY RAIN.

.LONG TERM...WEDNESDAY THROUGH SUNDAY

A COUPLE OF WEATHER SYSTEMS WILL MOVE THROUGH THE AREA WED AND
THURSDAY. SHOWERS AND STORMS WILL BE THE RESULT BOTH DAYS WITH
GREATER COVERAGE OVER AND NEAR THE MOUNTAINS AND ACROSS THE LOWER
ELEVATIONS OF THE NORTH. ISOLATED COVERAGE FOR THE CENTRAL AND
SOUTH ZONES. FRIDAY LOOKS MOSTLY DRY AT THIS POINT WITH A RIDGE OF
HIGH PRESSURE MOVING OVERHEAD. MOISTURE RETURNS IN A SW FLOW ALOFT
ON SATURDAY INTO SATURDAY NIGHT. WIDELY SCATTERED SHOWERS AND
STORMS TO DEVELOP AND THIS ACTIVITY COULD LINGER PAST MIDNIGHT
SATURDAY NIGHT. NEXT SUNDAY LOOKS UNSETTLED AT THIS TIME WITH A
WEATHER SYSTEM PASSING THROUGH THE AREA. GFS MODEL IS MORE
AGGRESSIVE WITH THE SYSTEM WHILE THE ECMWF MODEL WEAKENS THE
SYSTEM AS IT MOVES BY. FOR NOW WIDELY SCATTERED SHOWERS AND STORMS
FOR THE WEST AND NORTH WITH LESSER COVERAGE CENTRAL AND SOUTH.
PLENTY OF TIME TO WATCH THIS WEATHER SCENARIO UNFOLD FOR NEXT
WEEKEND. MODELS ARE TRENDING A LITTLE COOLER WITH HIGH TEMPS
WEDNESDAY AND THURSDAY WITH COOLER 700MB TEMPS AND MORE CLOUDS.
VERY WARM TO HOT ON FRIDAY WITH MORE SUNSHINE AND WARMER 700MB
TEMPS. THEN SLIGHTLY COOLER NEXT SATURDAY AND SUNDAY.

&&

.AVIATION.../12Z ISSUANCE/

VFR CONDITIONS WITH MOSTLY UNLIMITED CIGS WILL PREVAIL THROUGH THE
PERIOD WITH GENERALLY LIGHT WIND LESS THAN 10KTS.  THE PREVAILING
SFC WIND WILL BECOME N-NE IN THE AFTERNOON.

AN UPPER LEVEL DISTURBANCE WILL LIFT NORTH ACROSS THE GREAT BASIN
SUNDAY NIGHT...SPREADING INCREASING MID-LEVEL MOISTURE...SCT-BKN
FL130-150...AND A FEW SHOWERS VCNTY AND SOUTH OF INTERSTATE 80 AFTER
06Z MONDAY.

&&

.FIRE WEATHER...

ENHANCED FIRE DANGER AGAIN TODAY AS HOT AND DRY CONDITIONS CONTINUE
WITH MINIMUM RH VALUES EXPECTED TO REMAIN IN THE LOW TO MID TEENS
ACROSS THE LOWER ELEVATIONS...WITH UPPER TEENS AND 20S OVER THE
MOUNTAINS. EXPECT GENERALLY LIGHT TO MODERATE WINDS TODAY FROM THE
NORTH TO NORTHEAST AT 5 TO 15 MPH. ADDITIONALLY...THE VERY DRY
ATMOSPHERE WITH HIGHER PRESSURE AT THE SURFACE AND ALOFT WILL ALLOW
ONLY ISOLATED CHANCE FOR PRECIPITATION ACROSS THE HIGHER MOUNTAIN
RANGES. CHANGES ARE ON THE WAY HOWEVER...FOR BOTH MONDAY AND TUESDAY
AS AN UPPER LEVEL DISTURBANCE DRAGS ALONG SOME GOOD MONSOONAL-LIKE
MOISTURE INTO THE REGION. INCREASING CHANCES FOR SHOWERS AND
EMBEDDED THUNDER WILL BEGIN MONDAY MORNING ACROSS THE FAR SOUTHERN
ZONES...WITH AREAS WEST OF THE DIVIDE SEEING FIRST DROPS...SPREADING
INTO THE CENTRAL AND NORTHERN FORECAST AREA MONDAY NIGHT...ENDING UP
ACROSS EASTERN/NORTHEASTERN WYOMING BY TUESDAY AFTERNOON...LASTING
INTO THE EVENING. FIRE DANGER WILL DECREASE BOTH MONDAY AND
TUESDAY...EXCEPT FOR A COUPLE OF POSSIBLE FIRE STARTS DUE TO
LIGHTNING STRIKES.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE

&&

$$

SHORT TERM...BRAUN
LONG TERM...AR
AVIATION...AEM
FIRE WEATHER...BRAUN


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