Area Forecast Discussion
Issued by NWS Riverton, WY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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 101747 AAA
AFDRIW

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE RIVERTON WY
1147 AM MDT THU APR 10 2014

.SHORT TERM...THURSDAY THROUGH SATURDAY NIGHT

STILL SOME SHOWERS AROUND WEDNESDAY NIGHT WITH A FRONTAL BOUNDARY
OVER THE AREA BUT THESE ARE MAINLY OF THE LIGHT VARIETY. THESE
SHOULD CONTINUE TO WANE LATE TONIGHT WITH MOST AREAS BEING MAINLY
DRY BY THURSDAY MORNING. THERE MAY BE JUST ENOUGH INSTABILITY AND
MOISTURE LEFT OVER FOR A COUPLE OF STRAY SHOWERS TO POP OVER THE
HIGHER ELEVATIONS BUT A RULE WE LEFT MOST AREAS DRY FOR TODAY.
TEMPERATURES WILL COOL SOMEWHAT TODAY AS COMPARED TO YESTERDAY BUT
STILL MILD AND ABOVE NORMAL FOR THIS TIME OF YEAR. EXPECT DRY
WEATHER EVERYWHERE ON FRIDAY AND WITH SOUTHWEST FLOW INCREASING
TEMPERATURES WILL RECOVER CLOSE TO THE HIGH TEMPERATURES ON
WEDNESDAY. WE WILL STILL BE SOME GUSTY BREEZES AT TIMES ALTHOUGH
NOTHING UNUSUAL FOR APRIL IN WYOMING.

AND THEN THE FUN STARTS AS WINTER CRIES OUT...I AM NOT DONE YET. A
COLD FRONT WILL BEGIN TO DROP SOUTHWARD TOWARD WYOMING. MOST AREAS
LOOK TO STAY DRY THROUGH FRIDAY NIGHT SO WE CUT BACK POPS. MODELS
HAVE DIFFERENT TIMING IN DROPPING THE FRONT SOUTHWARD WITH THE GFS A
BIT FASTER THAN THE NAM. AS A RESULT...THIS RAISES THE DILEMMA WITH
HIGH TEMPERATURES FOR SATURDAY. IF THE NAM WORKS OUT TEMPERATURES
COULD BE SEVERAL DEGREES WARMER THAN WHAT WE HAVE ACROSS CENTRAL
WYOMING. FOR NOW...WE MADE FEW CHANGES AND WILL WAIT TO SEE IF
MODELS COME INTO BETTER AGREEMENT. THE SPREAD OF PRECIPITATION IS
ALSO DIFFERENT. THE NAM KEEPS MOST AREAS DRY THROUGH SATURDAY
MORNING WITH THE GFS AND EUROPEAN SPREADING PRECIPITATION INTO
NORTHERN AREAS. FOR NOW...WE WENT WITH A COMPROMISE WITH MAINLY
SLIGHT CHANCES ACROSS THE NORTH. ONE CHANGE WE DID MAKE WAS TO
REMOVE POPS FROM PORTIONS OF THE WIND RIVER BASIN DURING THE
AFTERNOON AS MOST MODELS KEEP THIS AREA DRY. OTHERWISE...FEW CHANGES
WITH THE AFTERNOON FORECAST WITH THE X FACTOR BEING HOW QUICKLY COLD
AIR CAN DRAIN INTO THE NORTH AND CHANGE PRECIPITATION TO SNOW.
AGAIN...FEW CHANGES WERE MADE.

PRECIPITATION COVERAGE SHOULD REALLY INCREASE ACROSS THE AREA
SATURDAY NIGHT AS THE COLDER AIR SETTLES SOUTH AND A COMBINATION OF
OVERRUNNING AND JET DYNAMICS REALLY GET THE SNOW MACHINE CRANKING.
MODELS AGAIN DIFFER ON THE PLACEMENT OF THE HEAVIEST SNOW. THE GFS
GIVES MORE OF A NORTHEASTERLY FLOW AT 700 MILLIBAR SOLUTION THAT
WOULD GIVE A GOOD SNOW FROM LANDER THROUGH CASPER WITH THE UPSLOPE
FLOW. THE NAM...MEANWHILE KEEPS THE BEST SNOW FURTHER NORTH AND EAST
WITH THE LEFT FRONT QUAD OF THE JET STREAM. AGAIN...WITH THE
UNCERTAINTY WE MADE FEW CHANGES AND LET CONTINUITY RIDE FOR NOW.

.LONG TERM...SUNDAY THROUGH THURSDAY

A SPRING SNOW STORM WILL BE ONGOING ACROSS THE FORECAST AREA SUNDAY
MORNING...WITH THE BRUNT OF IT ALONG AND EAST OF THE DIVIDE. HAVE
INCREASED POPS ESPECIALLY IN FAVORED UPSLOPE AREAS EAST OF THE
DIVIDE FOR SUNDAY MORNING. THE STORM SYSTEM WILL EXIT INTO THE
PLAINS SUNDAY NIGHT WITH THE SNOWFALL QUICKLY COMING TO AN END
SUNDAY EVENING. HAVE KEPT HIGH TEMPERATURES SUNDAY ABOUT 5 TO 10
DEGREES COLDER THAN GUIDANCE...DUE TO ANTICIPATED CLOUD COVER...SNOW
AND 700 MB TEMPS AROUND -10C.

AFTER A CHILLY START MONDAY MORNING...A MUCH WARMER AND DRY DAY WILL
OCCUR MONDAY AS AN UPPER RIDGE SPREADS OVER THE ROCKIES. HOWEVER
THIS WILL BE SHORT LIVED AS INCLEMENT WEATHER COULD RETURN AS EARLY
AS TUESDAY...ESPECIALLY OUT WEST AS THE RIDGE BREAKS DOWN. ALTHOUGH
THERE ARE DECENT MODEL DIFFERENCES IN THE WEDNESDAY/THURSDAY TIME
FRAME WITH THE TIMING/AMPLITUDE OF THE NEXT TROUGH...THEY GENERALLY
SHOW THE POTENTIAL FOR INCLEMENT WEATHER BOTH DAYS.

.AVIATION.../18Z ISSUANCE/

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

A WEAK UPPER DISTURBANCE WILL BRING SOME LOWER VFR CIGS TO VCNTY AND
NORTH OF KJAC-KDUB ALONG WITH SCT MTN -SHSN...PARTIAL MTN
OBSCURATIONS THIS AFTERNOON. W-NW WINDS AT 15-25 KTS WILL ALSO MIX
DOWN INTO MOST VALLEYS EARLY IN THE PERIOD. WINDS WILL DIMINISH WITH
SUNSET ALONG WITH CLEARING FROM NW-SE THIS EVENING.

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

W-NW SFC WINDS OF 15-25KTS ACROSS MOST AREAS WITH THE EXCEPTION
OF THE LOWER BIG HORN BASIN THIS AFTERNOON. A WEAK UPPER
DISTURBANCE WILL BRING ISOLATED-SCT MTN -SHSN/-SHRA ACROSS THE
NORTH IN THE AFTERNOON WITH PARTIAL MTN OBSCURATIONS. MAINLY MID
AND HIGH CLOUDS WITH A FEW SPRINKLES WILL BE FOUND OVER BASINS AND
VALLEYS. WINDS WILL DIMINISH WITH SUNSET ALONG WITH CLEARING NW-SE
THIS EVENING.

.FIRE WEATHER...

EXPECT MAINLY DRY WEATHER FROM THURSDAY MORNING THROUGH FRIDAY
EVENING. ISOLATED SHOWERS MAY LINGER TODAY ACROSS THE HIGHER
ELEVATIONS AND FAR EASTERN PORTIONS...ESPECIALLY IN THE MORNING.
AFTERNOONS WILL BECOME BREEZY TO WINDY AT TIMES THROUGH FRIDAY AS
WELL. A COLD FRONT DROPPING SOUTHWARD WILL BRING COLDER TEMPERATURES
AND CHANCE OF SNOW FROM LATER SATURDAY INTO SUNDAY.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...HATTINGS
LONG TERM...WM
AVIATION...ALLEN
FIRE WEATHER...HATTINGS





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