National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS65 KRIW 071613 AAA
AFDRIW

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE RIVERTON WY
913 AM MST FRI MAR 7 2014

.UPDATE...

A FLOOD ADVISORY HAS BEEN ISSUED FOR THE BIGHORN RIVER NEAR
WORLAND DUE TO ICE JAM FLOODING. THE DENSE FOG ADVISORY FOR
JOHNSON COUNTY HAS BEEN ALLOWED TO EXPIRE. PATCHY DENSE FOG COULD
PERSIST THROUGH THE MORNING...ESPECIALLY OVER LOCAL HIGH POINTS.

.SHORT TERM...FRIDAY THROUGH SUNDAY NIGHT

RATHER PROGRESSIVE 5 WAVE LW PATTERN (WHICH WE HAVE NOT BEEN PRIVY
TO MOST OF THE WINTER) WILL KEEPS THINGS ACTIVE AND UNSETTLED IN
BETWEEN BRIEF INTERLUDES WITH DRY/STABLE/NICE WEATHER. SPRING IS
FINALLY BEGINNING TO SHOW ITSELF.

DISCOMBOBULATED FRONT JUST STARTING TO ENTER THE NRN PORTIONS OF WY
TONIGHT...AND WILL ACCELERATE AS FRONTOGENESIS PROCEEDS AND TRACK
SWD OVERNIGHT...MOSTLY CLEARING THE STATE AND HEADING INTO CO BY
SUNRISE. OTHERWISE...MINUS 8 TO 10 DEG C H7 TEMPS HAVE REPLACED THE
MINUS 3 DEG C THAT WE HAD 24 HRS AGO...KEEPING THE THE FA UNDER LOW
END UNSTABLE CONDITIONS WITH ISOLATED TO WIDELY SCATTERED RAIN/SNOW
SHOWERS AROUND THE REGION. AREAS BEST SUITED FOR GETTING MEASURABLE
AMOUNTS OF LIQUID INCLUDE THE WRN WIND RIVER MOUNTAINS...SRN
ABSAROKAS...AND THE BIG HORN MOUNTAINS WITH MUCH LESS/LIGHTER
CHC/AMOUNTS IN BETWEEN. SAT IMAGERY SHOWS MAIN TROF AXIS CUTTING
FROM N TO S RIGHT THRU THE CENTER OF ID AND WILL MOSTLY CLEAR THE
CWA BY THIS EVENING...WITH PRECIP CHCS GENERALLY FOLLOWING THIS W TO
E SHIFT THRU THE DAY. PATCHY FOG WILL ALSO BE POSSIBLE AROUND THE
CWA THIS MORNING...AND PERHAPS AGAIN SAT MORNING. WILL WAIT TO SEE
WHAT KIND OF ABOVE SFC DRYING PROCEEDS LATER TONIGHT.

POST FRONTAL LIGHT CONVECTIVE PRECIP WILL LINGER THRU TODAY WITH
COLD MID/UPR LVLS CONTINUING TO KEEP THING JUST ENOUGH UNSETTLED TO
PRODUCE SOME SHOWERY BOUTS OF RAIN OR SNOW SHOWERS. ONLY UP TO A
COUPLE OF INCHES AT MOST SHOULD BE EXPECTED IN FAVORED LOCATIONS
TODAY. TONIGHT THROUGH SUN...ATMOSPHERE DRIES OUT STATE WIDE WITH HI
SFC P AND UPR RIDGING LARGELY PROTECTING THE FA. BRIGHT SUNSHINE
WILL TAKE OVER THE STATE SAT WITH HIGH TEMPS CLIMBING BACK INTO THE
UPPER 40S AND 50S E OF THE DIVIDE AND MOSTLY 40S WEST AFTER A COOL
FRI. SAT NIGHT...W TO SW WINDS WILL ONCE AGAIN BEGIN TO INCREASE OVR
AND IN THE LEE OF THE ABSAROKA MOUNTAINS...POSSIBLY GETTING DOWN
INTO THE CODY FOOTHILL REGION. ATTM...IT DOES NOT LOOK LIKE A
WARNING SITUATION...ALTHOUGH BY SUN AFTERNOON IT SHOULD BE QUITE
GUSTY IN ALL OF THE USUAL SPOTS. GENERALLY SPEAKING...WARMING SHOULD
BE WELL ON THE WAY BY SUN E OF THE DIVIDE WITH NEAR 60 TO MID 60S
COMMONS AT LOWER ELEVATIONS. W OF THE DIVIDE...ALTHOUGH UNDER A
MODEST RIDGE...EPAC MOISTURE WILL BEGIN TO MOVE INTO THE WRN FA WITH
FETCH/TRAJECTORY OF LOW/MID LVL FLOW FAVORING TERRAIN FORCED PRECIP.
IT LOOKS LIKE UPR LVLS (JET PROXIMITY) WILL BE INCREASINGLY
FAVORABLE BY SUN NIGHT TO START TO AID IN SOME MODEST UPR QG FORCING
AHEAD OF THE NEXT LARGE TROF DUE TO REPLACE THE RIDGE LATER ON
MONDAY. WILL HAVE TO WATCH DEVELOPMENT INTO THE NRN
TETON/YELLOWSTONE AREA SUNDAY NIGHT AND ONWARD AS SIGNIFICANT PRECIP
MAY END UP FALLING THERE AT FOR THE BEGINNING OF THE NEXT WORK
WEEK.

.LONG TERM...MONDAY THROUGH FRIDAY
AS ELUDED AT THE END OF THE SHORT TERM DISCUSSION...A SIGNIFICANT
PRECIP EVENT MAY DEVELOP ACROSS PORTIONS OF THE AREA MONDAY INTO
TUESDAY. THIS SYSTEM IS NOW TRACKING ACROSS THE FAR WRN PACIFIC
AND EVEN THOUGH THERE ARE STILL TIMING DIFFERENCES...THE OP GFS
AND ECMWF ARE MUCH CLOSER IN AGREEMENT. THE ECMWF IS ABOUT 6 HOURS
FASTER BUT OTHERWISE...THEY ARE GOOD ENOUGH TO RAISE THE
CONFIDENCE AND INTRODUCE HIGHER POPS SPREADING FROM WEST TO EAST
MONDAY INTO MONDAY NIGHT. NICE ISENTROPIC UPGLIDE IMPACTS THE WEST
ON MONDAY WHILE MOST AREAS EAST OF THE DIVIDE WILL BE WINDY AND
DRY. THE FRONT MAY EDGE INTO THE FAR NORTH LATE IN THE DAY MONDAY
BUT OTHERWISE...EXPECT MILD TEMPERATURES IN THE 50S FOR MOST OF
CENTRAL WYOMING. THINGS CHANGE MONDAY NIGHT EAST OF THE
DIVIDE...AS THE UPPER LOW DIGS INTO IDAHO AND POTENTIALLY CLOSES
OFF AS IT TRACKS ACROSS SRN WYO OR NRN CO MONDAY NIGHT AND TUESDAY
MORNING. STILL TOO FAR AWAY TO HAVE HIGH CONFIDENCE BECAUSE OF THE
POTENTIAL COMPLEXITY OF THE TROUGH BUT AT LEAST THE MODELS ARE
STARTING TO COME TOGETHER BETTER TONIGHT. POTENTIAL SIGNIFICANT
SNOWSTORM IS POSSIBLE FOR THE WRN WYOMING MOUNTAINS MONDAY AND
MONDAY NIGHT...AND IN PORTIONS OF CENTRAL WYOMING MONDAY NIGHT AND
TUESDAY. IF THE STORM LAYS DOWN SOME FRESH SNOW THEN WEDNESDAY
MORNING COULD BE QUITE CHILLY WITH COLD TEMPERATURES ALOFT...FRESH
SNOW COVER AND LIGHT WINDS. SLOW WARM-UP ON WEDNESDAY WITH FURTHER
WARMING TUESDAY. MARCH SUN WILL HELP. MODELS DIVERGE AT THE END OF
THE PERIOD. LAST NIGHT IT WAS THE ECMWF THAT SHOWED A LOW BARGING
UNDERNEATH THE WRN U.S. RIDGE AND TONIGHT IT IS FURTHER NORTH IN
MONTANA BUT STILL CLOSE ENOUGH FOR POTENTIAL SNOW IN THE
MOUNTAINS. THE GFS NOW SHOWS AN UPPER LOW TOO BUT MUCH FURTHER
SOUTH AND DIGGING INTO NEVADA FRIDAY. ONLY INTRODUCED SOME SMALL
POPS IN MAINLY THE MOUNTAINS FOR NOW WITH HIGH UNCERTAINTY ON HOW
THIS SYSTEM MAY ACTUALLY TRACK.

&&

.AVIATION.../12Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

ISOLATED TO LOCALLY SCATTERED CONVECTION WILL BE POSSIBLE EARLY THIS
MORNING...WITH A CONCENTRATION OVER JOHNSON AND NATRONA COUNTIES.
THE BEST SHOT AT WIDESPREAD PRECIP WILL BE AROUND KCPR WHERE THERE
IS THE POTENTIAL FOR A BRIEF PERIOD OF UPSLOPE INDUCED LIGHT
SNOWFALL...IN COMBINATION WITH ACTIVITY SLIDING SOUTHEAST OFF THE
BIGHORN MOUNTAINS THIS MORNING. THUS MVFR CEILINGS ARE LIKELY THIS
MORNING ACROSS NATRONA AND JOHNSON COUNTIES...WITH LOCALIZED IFR
AREAS. PARTS OF THE BIG HORN BASIN COULD ALSO SEE SOME FOG THIS
MORNING...BUT COUNTING ON MID LEVEL CLOUDS/ISOLD SHOWERS TO KEEP FOG
TO A MINIMUM. OTHERWISE...ISOLATED TO SCATTERED MOUNTAIN SNOW
SHOWERS WILL REMAIN THROUGH THE DAY...PUSHING SOUTHEAST INTO THE
LOWER ELEVATIONS AT TIMES...ESPECIALLY IN THE AFTERNOON. DRIER
CONDITIONS AND DECREASING CLOUDINESS ARE EXPECTED TONIGHT. WINDS
WILL GENERALLY BE LIGHT NORTHERLY OR VARIABLE TODAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

FOG WILL BE THE MAIN CONCERN ACROSS THE UPPER GREEN RIVER BASIN THIS
MORNING...WHILE MVFR CEILINGS AND POSSIBLY LINGERING LIGHT SNOW
SHOWERS COULD CONTINUE TO IMPACT KJAC THIS MORNING. THIS AFTERNOON
THE MAIN CONCERN WILL BE MAINLY SNOW SHOWERS DEVELOPING OVER THE
MOUNTAINS AND PUSHING SOUTHEAST INTO THE LOWER ELEVATIONS.  DRIER
CONDITIONS AND DECREASING CLOUDINESS ARE EXPECTED TONIGHT...WITH THE
POSSIBILITY OF FOG IN THE WESTERN VALLEYS AND BASINS.

&&

.FIRE WEATHER...

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND. WIDESPREAD LIGHT
SHOWER ACTIVITY WILL BE POSSIBLE ACROSS THE ENTIRE REGION
TODAY...BUT WILL HAVE LESS AND LESS MOISTURE TO WORK WITH THROUGH
THE DAY. ONLY A COUPLE OF INCHES OF ADDITIONAL SNOWFALL CAN BE
EXPECTED IN THE HIGHER FAVORED REGIONS OF THE MOUNTAINS TODAY...WITH
ONLY A TRACE TO LESS THAN AN INCH ELSEWHERE. SATURDAY WILL BE HIGH
AND DRY ACROSS THE REGION WITH PLENTY OF SUNSHINE AND A WARMING
TREND BEGINNING...WITH TEMPERATURES RISING NEAR OR INTO THE 60S
ACROSS MOST OF THE LOWER ELEVATIONS EAST OF THE DIVIDE ON SUNDAY.
WINDS WILL BEGIN TO GET GUSTY ONCE AGAIN ACROSS THE USUAL WIND
CORRIDOR IN THE SOUTH AND SOUTHEAST ZONES...AS WILL AS IN THE WIND
RIVER AND ABSAROKA MOUNTAINS BY SATURDAY NIGHT. THE NEXT
PRECIPITATION PRODUCING SYSTEM WILL BEGIN TO ARRIVE SUNDAY NIGHT IN
THE WESTERN MOUNTAINS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
FLOOD ADVISORY UNTIL 9AM MST SATURDAY MORNING WY006.

&&

$$

UPDATE...ALLEN
SHORT TERM...BRAUN
LONG TERM...SKRBAC
AVIATION...WM
FIRE WEATHER...BRAUN