Issued by NWS Riverton, WY
000 FXUS65 KRIW 162228 AFDRIW AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 428 PM MDT THU OCT 16 2008 .SHORT TERM...TONIGHT THROUGH SUNDAY A SHORTWAVE MOVED ACROSS THE REGION TODAY WITH SNOW IN THE NW MOUNTAINS AND SNOW SHOWERS IN THE FAR WEST VALLEYS EARLIER TODAY. NORTHERN BIGHORN MTS ALSO HAVE SEEN A FEW SNOW SHOWERS. OTHERWISE THE CLOUDS HAVE DECREASED OVER THE LOWER ELEVATIONS WITH ONLY ISOLATED SNOW SHOWERS IN THE MTS. BREEZY AREAS AS WELL TODAY. A FEW SNOW SHOWERS WILL OCCUR THIS EVENING OVER THE NW MTS AND NORTHERN BIGHORN MTS BEFORE ENDING AROUND MIDNIGHT. OTHERWISE A DRY NIGHT WITH THE WIND DECREASING. SEASONAL LOW TEMPS WITH A FEW PLACES COLD DUE TO LINGERING SNOW COVER IN THE VALLEYS. FRIDAY LOOKS DRY AND WARMER WITH HIGH PRESSURE OVER THE REGION. A LEE TROF SETS UP FRI PM WITH SOME BREEZES IN FAVORED PLACES. RAISED TEMPS A BIT IN PLACES THAT NO LONGER HAVE SNOW COVER. FLOW ALOFT TURNS SW ON SATURDAY AS A WEAK TROUGH ENTERS INTO THE WESTERN U.S. THIS WILL BRING WARMER TEMPS ALOFT TO THE AREA ALONG WITH A STRONGER LEE TROF. BREEZY AREAS TO LOCALLY WINDY IN FAVORED PLACES SATURDAY. SHOULD SEE MILD HIGHS ONCE AGAIN ON SATURDAY AND RAISED HIGHS IN SOME PLACES. THE WEAK SHORTWAVE TROUGH MOVES TOWARD THE AREA SAT NIGHT AND THROUGH THE WY ON SUNDAY. THE BEST MOISTURE LOOKS TO BE OVER THE NORTH AND THE MTS. HAVE MADE SOME ADJUSTMENTS TO PRECIP CHANCES SAT NIGHT AND SUNDAY. MAY NEED MORE COVERAGE IN THE MTS DEPENDING ON HOW STRONG THE TROUGH LOOKS WITH TIME. HIGH TEMPS A LITTLE COOLER ON SUNDAY WITH TROUGH PASSAGE. .LONG TERM...SUNDAY NIGHT THROUGH THURSDAY MODELS HAVE COME IN MUCH BETTER AGREEMENT TONIGHT IN REGARDS TO OUR TUESDAY STORM SYSTEM. LAST NIGHT WE SIDED WITH THE GFS BECAUSE ITS PROGRESSIVE NATURE WAS SUPPORTED BY AN ANALYSIS OF THE H5 HEMISPHERIC PATTERN. THE KICKER SYSTEM THAT WE SAW OVER ASIA IS OBVIOUSLY BEING HANDLED BETTER BY THE ECMWF AND THEY BOTH SHOW THIS SYSTEM AS A QUICK HITTER NOW. IN FACT...THE ECMWF IS NOT AS AGGRESSIVE AS EVEN THE GFS NOW AS THIS SYSTEM TRIES TO DROP SE ACROSS WYOMING. THE ECMWF IS TRYING TO SAY THIS SYSTEM MAY ONLY BRUSH OUR NERN ZONES TUESDAY. NOT GOING THAT FAR YET AND WILL KEEP OUR CHANCE POPS IN TUESDAY ACROSS THE NERN HALF OF OUR AREA BUT GRADUALLY DECREASE OR END THEM FROM WEST TO EAST INTO TUESDAY NIGHT. BEFORE THIS SYSTEM ARRIVES...WE HAVE A SHORTWAVE RIDGE FOR A DRY MONDAY BEFORE THE AFOREMENTIONED TUESDAY SYSTEM ARRIVES. WEDNESDAY SHOULD BE DRY AS A SHORTWAVE RIDGE MOVES RAPIDLY OVER THE AREA. ANOTHER MONTANA SHORTWAVE IS THEN FORECAST TO BRUSH OUR NRN ZONES ON THURSDAY. TEMPERATURES SHOULD REBOUND NICELY MONDAY IN ADVANCE OF OUR TUESDAY SYSTEM. AFTER A SHARP DROP TUESDAY...LIKELY MORE THAN WE HAVE IN OUR CURRENT GRIDS...WE SHOULD REBOUND AGAIN WEDNESDAY INTO THURSDAY WITH THE ECMWF`S REBOUND BEING MUCH FASTER WITH ITS MORE GLANCING BLOW SCENARIO. && .AVIATION... A WEAK DISTURBANCE IS MOVING THROUGH THE STATE TODAY. LIGHT SNOW SHOWERS WERE NOTED IN THE WESTERN MOUNTAINS AND SOME VALLEY LOCATIONS THIS MORNING AND EARLY AFTERNOON...CREATING MVFR CONDITIONS. SOME SHOWERS WILL BRIEFLY IMPACT AIRPORTS NEAR THE MOUNTAINS EARLY IN THE AFTERNOON...WITH BROKEN MID LEVEL CLOUDS MOVING TO THE EAST AS THE DAY PROGRESSES. THE MID LEVEL CLOUD DECKS WILL TRANSITION TO HIGHER CLOUDS AS THE EVENING PROGRESSES. SOME GUSTY WINDS WILL BE FELT FROM KRKS TO KCPR LATE THIS AFTERNOON...AND DIMINISH WITH NIGHTFALL. SOME LOW CLOUDS WITH VERY PATCHY FOG ARE POSSIBLE AROUND KBPI...KPNA...KJAC...KLND...AND KRIW TOMORROW MORNING. AS HIGH PRESSURE BUILDS IN FRIDAY...CLEARING SKIES WITH A FEW CLOUDS IN NW WYOMING ALONG WITH GENERALLY LIGHT WINDS ARE EXPECTED. GUSTY WINDS AROUND 20 KNOTS WILL ALSO DEVELOP FROM KRKS TO KCPR. && .FIRE WEATHER... OTHER THAN A FEW SNOW SHOWERS OVER THE NORTHWEST MOUNTAINS AND THE NORTHERN BIGHORN MOUNTAINS THIS EVENING...THE REGION WILL BE DRY TONIGHT. THE SNOW SHOWERS SHOULD DECREASE AFTER MIDNIGHT. DRY AND WARMER WEATHER IS ON TAP FOR FRIDAY AND SATURDAY ACROSS THE DISTRICT. THERE WILL BE BREEZY AREAS IN THE EAST CENTRAL AND THE SOUTH FRIDAY AND AGAIN SATURDAY. RELATIVE HUMIDITY VALUES WILL BE LOWERING IN THE AFTERNOON BOTH DAYS WHERE SNOW COVER HAS MELTED AND THE GROUND CONTINUES TO DRY. THE NEXT CHANCE OF RAIN AND SNOW WILL BE ON SUNDAY AS A WEATHER SYSTEM MOVES ACROSS MONTANA AND NORTHERN WYOMING. && .RIW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...AR LONG TERM...SKRBAC AVIATION...MCDONALD FIRE WEATHER...AR
