286
FXUS65 KRIW 210842
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
242 AM MDT THU OCT 21 2021
SHORT TERM
(TODAY THROUGH FRIDAY)
ISSUED AT 239 AM MDT THU OCT 21 2021
AS OPPOSED TO THE LAST SEVERAL DAYS, A QUIET SHORT TERM FORECAST IS
IN STORE. RIDGING HAS DEVELOPED ACROSS THE REGION, WHICH WILL KEEP
MOST AREAS WARM AND DRY AS WE HEAD INTO THE WEEKEND. A QUICK-MOVING
SHORTWAVE WILL CLIP NORTHWESTERN WY TODAY, WHICH COULD BRING SOME
VERY ISOLATED SHOWERS ACROSS YELLOWSTONE PARK AND THE NORTHERN
ABSAROKAS THIS MORNING. HIGH CLOUDS INCREASE OVERNIGHT AHEAD OF THIS
SHORTWAVE AS WELL, WHICH MAY MODERATE THE RADIATIONAL COOLING
OVERNIGHT. WITH THE RESIDUAL MOISTURE ACROSS THE LOWER WIND RIVER
BASIN AND NATRONA COUNTY ALONG THE NORTH PLATTE RIVER, COULD SEE
SOME PATCHY FOG THIS MORNING AGAIN. ADDED A LITTLE BIT OF PATCHY FOG
IN THE GRIDS THROUGH 17Z TO COVER THIS POSSIBILITY. TEMPS WILL
INCREASE INTO THE 60S ACROSS THE BIGHORN BASIN AND NORTHERN JOHNSON
COUNTY AND LIKELY REMAIN IN THE 50S ELSEWHERE. BREEZY AGAIN ACROSS
THE WIND CORRIDOR DURING THE AFTERNOON.
TOMORROW WILL SEE MUCH OF THE SAME CONDITIONS AS THE RIDGE AXIS
MOVES NEARLY DIRECTLY OVERHEAD BY THE AFTERNOON. THIS WILL RESULT IN
EVEN WARMER TEMPS ACROSS THE REGION. MANY LOCATIONS WILL NEAR 60
WITH MID 60S ACROSS THE BIGHORN BASIN AND JOHNSON COUNTY. LOW 60S
ARE EVEN POSSIBLE ACROSS THE WESTERN VALLEYS. BREEZY WINDS WILL ONCE
AGAIN OCCUR ACROSS THE WIND CORRIDOR. FRIDAY WILL ALSO BE DRY WITH
PARTLY CLOUDY SKIES. HIGH CLOUDS WILL INCREASE AGAIN FRIDAY
AFTERNOON AHEAD OF THE NEXT SYSTEM, WHICH WILL IMPACT THE REGION FOR
THE WEEKEND, BUT MORE ON THIS IN THE EXTENDED FORECAST.
LONG TERM
(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 239 AM MDT THU OCT 21 2021
AN ACTIVE PATTERN IS STILL EXPECTED INTO NEXT WEEK. SEVERAL WEATHER
SYSTEMS WILL PASS THROUGH THE REGION WITH FREQUENT CHANGES TO
WEATHER CONDITIONS ACROSS THE FORECAST AREA. A STRONG TO EVEN SEVERE
WIND EVENT IS POSSIBLE MONDAY, ESPECIALLY ALONG THE WIND CORRIDOR
FROM ROCK SPRINGS TO CASPER.
SHORTWAVE TROUGH SWINGS NORTH LATE FRIDAY AND CLIPS NORTHWEST
WYOMING. MID-LEVEL ENERGY ASSOCIATED WITH THIS TROUGH SHOULD STAY
NORTH AND WEST OF THE AREA. SOME SNOW SHOWERS ARE POSSIBLE AT HIGH
ELEVATIONS IN THE NORTHWEST PORTION OF THE FORECAST AREA. THE LARGER
UPPER-LEVEL SYSTEM MOVES THROUGH SATURDAY WITH A BETTER CHANCE FOR
PRECIPITATION ACROSS THE WEST. FOR LOWER ELEVATIONS ONSET OF
PRECIPITATION SHOULD BE IN THE FORM OF RAIN. 700MB TEMPERATURES
SATURDAY NIGHT DROP TO AROUND -6 C, SO A CHANGE OVER TO SNOW IS
POSSIBLE. THEN A RAIN/SNOW MIX IS POSSIBLE SUNDAY MORNING, BUT
PRECIPITATION SHOULD DECREASE INTO THE AFTERNOON AS A RIDGE
DEVELOPS. IT'S POSSIBLE PRECIPITATION HOLDS ON IN THE WESTERN
MOUNTAINS. THIS PRECIPITATION IS NOT EXPECTED TO MAKE IT EAST OF
THE WIND RIVER AND ABSAROKA MOUNTAINS. SATURDAY WINDS WILL BE
GUSTY FROM ROCK SPRINGS TO CASPER ALONG THE WIND CORRIDOR. SUNDAY
NIGHT WINDS SHOULD DECREASE IN INTENSITY AS THE RIDGE MOVES
OVERHEAD AND THE PRESSURE GRADIENT DECREASES.
MONDAY AND TUESDAY WILL BE THE MOST IMPACTFUL PERIOD FOR WEATHER
CONDITIONS ACROSS THE AREA. A DEEP TROUGH MOVES IN FROM THE WEST
WITH STRONG WARM AIR ADVECTION AHEAD OF IT. MONDAY AFTERNOON A VERY
TIGHT PRESSURE GRADIENT IS SITUATED ACROSS THE AREA. OVER THE
SOUTHEAST 700MB WINDS MAX OUT ANYWHERE FROM 55-65 KNOTS. CURRENTLY
SURFACE GUSTS ARE EXPECTED TO BE IN THE 50-60 MPH RANGE ACROSS THE
SOUTHEAST WIND CORRIDOR. WINDS WILL ALSO BE STRONG IN THE MOUNTAIN
PASSES THROUGHOUT THE FORECAST AREA. THESE VALUES COULD INCREASE IN
THE COMING DAYS AS WE GET A BETTER HANDLE ON THE SYSTEM. THIS SYSTEM
IS NOT EXPECTED TO BE A BIG PRECIPITATION MAKER. IT LOOKS TO BE TOO
PROGRESSIVE WITH A SINGLE BAND OF PRECIPITATION EAST OF THE DIVIDE
POSSIBLE ALONG THE COLD FRONT TUESDAY, OTHERWISE THE MOUNTAINS
SHOULD SEE THE BULK OF THE RAIN AND SNOW. TUESDAY NIGHT NORTHWEST
WINDS BEHIND A COLD FRONT SHOULD BE GUSTY ACROSS THE AREA.
AS THE BACKSIDE JET MOVES IN ON WEDNESDAY THERE SHOULD STILL BE
ENOUGH MOISTURE IN THE WESTERN MOUNTAINS FOR PRECIPITATION TO
CONTINUE THERE WITH NORTHWEST FLOW. WEST WINDS CONTINUE ON WEDNESDAY
AND COULD BE GUSTY, BUT NO AREAS WILL SEE EVEN CLOSE TO THE VALUES
EXPECTED ON MONDAY. BEYOND WEDNESDAY A BROAD RIDGE SHOULD BEGIN TO
BUILD ACROSS THE REGION, WHICH SHOULD QUIET THINGS DOWN FOR A BIT.
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 239 AM MDT THU OCT 21 2021
WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS TERMINALS
ALL TERMINALS TO BE VFR THROUGH THE FORECAST PERIOD. MID AND HIGH
CLOUD COVER INCREASES PERSISTS THROUGH THURSDAY MORNING. A FEW SNOW
SHOWERS AND OBSCURED MOUNTAIN TOPS POSSIBLE UNTIL 15Z/THURSDAY
BEFORE THE WAVE CLEARS THE REGION AROUND MIDDAY THURSDAY. SURFACE
WIND SPEEDS TO BE GENERALLY 10 KTS OR LESS THROUGH 12Z/FRIDAY. A
MAINLY CLEAR SKY IS EXPECTED AFTER 21Z THURSDAY.
EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL TERMINALS
VFR TO PREVAIL AT ALL TERMINALS THROUGH THE PERIOD. MID AND HIGH
CLOUD COVER CONTINUES THROUGH TOMORROW AROUND 18Z THURSDAY. KCPR
SOUTHWEST SURFACE WIND WILL INCREASE AGAIN AROUND MIDDAY THURSDAY
AND CONTINUE THROUGH THE AFTERNOON BEFORE DECREASING AGAIN SHORTLY
AFTER SUNSET. ALL OTHER TERMINALS TO SEE WIND LESS THAN 10 KTS.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZDV AND ZLC FOR
THE LATEST INFORMATION ON ICING AND TURBULENCE FORECASTS.
FIRE WEATHER
ISSUED AT 239 AM MDT THU OCT 21 2021
TODAY AND TOMORROW WILL SEE MAINLY JUST HIGH CLOUDS AND DRY
CONDITIONS. A FEW ISOLATED SHOWERS ARE POSSIBLE ACROSS THE FAR
NORTHWEST THIS MORNING, BUT NO ACCUMULATION IS EXPECTED, AS ANY
SHOWER WOULD BE BRIEF AND VERY LIGHT. BREEZY SW WINDS WILL OCCUR
ACROSS THE USUAL AREAS DURING THE AFTERNOONS. TEMPERATURES WILL BE
SEASONAL TO JUST ABOVE NORMAL OVER THE NEXT FEW DAYS. A SYSTEM WILL
MOVE INTO WESTERN WY THIS WEEKEND, WHICH COULD BRING A FEW INCHES OF
SNOW TO THE WESTERN MOUNTAINS, WITH A BIT OF RAIN FOR THE VALLEYS. A
MORE POTENT TROUGH WILL MOVE INTO THE REGION FOR THE EARLY PART OF
THE WEEK, WHICH WILL BRING VERY GUSTY SW WINDS TO THE WIND CORRIDOR.
GUSTS OVER 60 MPH ARE POSSIBLE ACROSS PARTS OF ZONES 280 AND 289
MONDAY AFTERNOON DUE TO A VERY STRONG JET AHEAD OF THE TROUGH.
PRECIPITATION WILL BE MINIMAL EAST OF THE DIVIDE WITH BOTH SYSTEMS,
BUT WEST OF THE DIVIDE WILL LIKELY SEE SOME RAIN AND SNOW SHOWERS
BEGINNING SATURDAY AFTERNOON THROUGH THE EARLY PART OF NEXT WEEK.
RIW WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...HENSLEY
LONG TERM...ROWE
AVIATION...AR/HATTINGS
FIRE WEATHER...HENSLEY
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