Area Forecast Discussion
Issued by NWS Riverton, WY

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
000
FXUS65 KRIW 250924
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
324 AM MDT SAT OCT 25 2014

.SHORT TERM...TODAY THROUGH MONDAY NIGHT

IMAGERY SHOWS FLAT RIDGING CONTINUING ACROSS THE INTERMOUNTAIN WEST
WITH TROFFING WELL OFF TO THE WEST AND EAST. STRONG JET SURROUNDS
THE WRN AND NRN PORTIONS OF WY. AT THE SFC...WEAK HIGH PRESSURE
ACROSS THE REGION WITH A WEAK NEARLY STATIONARY FRONT STRETCHING
FROM THE NW FA...ALONG THE LEE SIDE OF THE ABSAROKAS AND OFF TO THE
ESE THRU NATRONA COUNTY AND POINTS FURTHER EAST.

OVERALL A BIT SLOWER AND DRIER EVENT SHAPING UP TODAY THRU MONDAY
WHEN COMPARED TO WHAT IT LOOKED LIKE THE PAST FEW DAYS. STRONG FLOW
ALOFT...WARM LL TEMPS WITH GOOD LAPSE RATES UP THRU 600 MB WILL
ALLOW FOR INCREASED WIND TODAY AND SUNDAY. AFTERNOON WINDS WILL COME
UP ACROSS THE SRN/SERN WIND CORRIDOR...WHILE NOCTURNAL WINDS
INCREASE DRAMATICALLY OVER/NEAR THE LEE PORTIONS OF THE MAJOR
MOUNTAIN RANGES...WITH PERHAPS SOME OCCASIONAL SPILL INTO THE LOWER
ELEVATIONS. TONIGHT... OVER/NEAR THE NORTHERN ABSAROKAS AND ADJACENT
CODY FOOTHILLS...INCREASINGLY FAVORABLE CONDITIONS FOR MOUNTAIN WAVE
PRODUCTION WILL OCCUR LATER TONIGHT...LASTING THRU SUNDAY MORNING. A
HIGH WIND WATCH HAS BEEN ISSUED WITH THIS IN MIND...WITH WARNING
CONDITIONS OCCURRING BY MIDNIGHT TONIGHT AND LASTING UNTIL AROUND
NOON ON SUNDAY. EXTENDED WARNING BY 3 HRS. GOOD LOW TO MID LVL
THERMAL AND OMEGA GRADS TONIGHT INDICATE MAX MOUNTAIN WAVE ACTION
BETWEEN 09Z AND 15Z SUNDAY. ADDITIONALLY...THE UPR LVLS TRANSITION
INTO A MORE SOUTHWEST UPR FLOW PATTERN TODAY THRU SUNDAY WITH THE
WRN TROF RAPIDLY APPROACHING THE REGION.  OVERNIGHT
TONIGHT...MOISTURE WILL START TO FEED INTO THE WRN FA ALONG WITH
INCREASING VORTICITY AND LIFT. THIS WILL PUSH A COLD FRONT THRU
SUNDAY AFTERNOON...ALLOWING SHRA/SHSN TO DEVELOP AND SPREAD ACROSS
MUCH OF THE WRN FA THRU THE REST OF THE DAY ON SUNDAY....THEN THE
NORTHERN ZONES MONDAY. ATTM...LIMITED MOISTURE AND DEEP RELATIVELY
WARM TEMPS WILL KEEP THE SNOW ON THE WET AND ON THE LOWER END OF THE
ACCUMULATION SCALE...MAXING OUT AT LESS THAN 6 INCHES OVER THE
HIGHEST PEAKS FOR THE MOST PART OVR A 30 HR PERIOD THRU MON MORNING.
DOWNSLOPE WIND ACROSS MUCH OF THE LOWER ELEVATIONS WILL KEEP MOST
PRECIP AWAY DURING THE SAME PERIOD OF TIME. FAIRLY NICE DAY ACROSS
MOST OF THE SRN 3/4S OF THE CWA MONDAY...WITH SKIES CLEARING QUICKLY
OVERNIGHT MONDAY.

.LONG TERM...TUESDAY THROUGH SATURDAY

TUESDAY WILL BE DRY WITH A NW FLOW ALOFT. THE NEXT WEATHER SYSTEM
WILL IMPACT NW WY LATE TUE NIGHT AND THIS SYSTEM WILL PUSH THROUGH
THE AREA ON WEDNESDAY INTO WED EVENING. SCATTERED SHOWERS LOWER
ELEVATIONS WITH SCATTERED RAIN AND SNOW SHOWERS FOR THE MOUNTAINS.
THURSDAY AND FRIDAY LOOK DRY WITH HIGH PRESSURE OVER THE REGION. THE
MODELS DIFFER NEXT SATURDAY WITH TIMING OF THE NEXT WEATHER SYSTEM.
THE GFS MODEL BRINGS IN A CHANCE OF PRECIP TO THE WEST AND A COLD
FRONTAL PASSAGE. CENTRAL AND EAST WOULD BE DRY...BREEZY AND MILD.
THE ECMWF MODEL KEEPS IT DRY ALL AREAS NEXT SATURDAY WITH BREEZY
AREAS. I WILL SIDE WITH THE ECMWF AND KEEP IT DRY NEXT SATURDAY. AS
FOR TEMPS...SEASONABLY MILD TUE THROUGH THURS...THEN ABOVE NORMAL
HIGHS NEXT FRI AND SATURDAY.

&&

.AVIATION.../12Z ISSUANCE/

VFR CONDITIONS UNDER SKC CONDITIONS ARE EXPECTED THROUGH 00Z. BREEZY
TO WINDY SOUTH TO SOUTHWEST WIND IN TYPICAL AREAS...WITH AN APPROACH
OF A STORM SYSTEM. AFTER 00Z...AREAS WEST OF THE DIVIDE WILL SEE
QUICKLY INCREASING MID LEVEL CLOUDINESS WITH SOME SHOWER ACTIVITY
POSSIBLE AFTER 03Z. MOUNTAIN TOPS WILL BECOME OBSCURED OVER THE FAR
WEST BETWEEN 03Z AND 06Z. SOME MVFR CONDITIONS COULD OCCUR IN OR
NEAR THIS CONVECTION.  HOWEVER OF MORE CONCERN...WILL BE
CONSIDERABLE MOUNTAIN TURBULENCE TONIGHT...AS WELL AS LLWS ON THE
LEE SIDE OF MOUNTAIN RANGES...ESPECIALLY AT COD AND LND.

PLEASE SEE THE AVIATION WEATHER CENTER FOR THE LATEST INFORMATION ON
TURBULENCE FORECASTS.

&&

.FIRE WEATHER...

FIRE DANGER WILL BE ELEVATED TODAY...MAINLY IN THE LEE OF THE
MOUNTAIN RANGES OVER THE BASINS EAST OF THE DIVIDE AS MINIMUM RH VALUES
ACROSS THESE AREAS FALL INTO THE MID AND UPPER TEENS WHILE WINDS
INCREASE OUT OF THE SOUTHWEST TO 15 TO 25 MPH WITH GUSTS OF 25 TO
TO 50 MPH AT TIMES. SUNDAY...MOISTURE WILL INCREASE ACROSS THE
ENTIRE REGION WITH A BETTER CHANCE FOR SHOWERS ACROSS THE WEST AND
NORTH...LOWERING FIRE DANGER ONCE AGAIN.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...

HIGH WIND WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING
WYZ002-003.

&&

$$

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







USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.