Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 241751
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1151 AM MDT SUN APR 24 2016

.SHORT TERM...TODAY THROUGH TUESDAY NIGHT

WINTER WEATHER ADVISORIES FOR THE WEST CANCELLED.  HIGH WIND
WARNING FOR JOHNSON COUNTY EXPIRES AT NOON.  GRADUAL IMPROVING
CONDITIONS FROM WEST TO EAST THROUGH THIS EVENING.  POSSIBLE
FOG TONIGHT.

SHOWERS CONTINUE TO INCREASE OVER THE AREA THIS MORNING AS THE AREA
OF LOW PRESSURE CONTINUES TO MOVE TOWARDS CENTRAL WYOMING. RADAR
CONTINUES TO DEMONSTRATE A DOWNWARD TREND ON LIGHTNING
ACTIVITY...THOUGH A FEW STRIKES HAVE STILL BEEN NOTED ACROSS THE
NORTHEASTERN PORTION OF THE STATE. SHOWERS WILL CONTINUE THROUGH THE
OVERNIGHT HOURS FOR MUCH OF THE AREA. THE AREA OF LOW PRESSURE WILL
CONTINUE ON ITS NORTHEASTERN PATH...LANDING AROUND THE
WYOMING/NEBRASKA/SOUTH DAKOTA BORDER BY THE MID MORNING HOURS. THIS
PLACEMENT ENCOURAGES THE PRODUCTION OF WRAPAROUND MOISTURE. WITH
THIS WRAPAROUND... MODELS SHOWING A STRONG PLUME OF MOISTURE
IMPACTING JOHNSON AND NATRONA COUNTIES THROUGH MUCH OF THE
AFTERNOON. PRECIPITATION CHANCES HAVE BEEN INCREASED ACROSS THE
AREA. ADDITIONALLY...TEMPERATURES AT CASPER MOUNTAIN SHOW THE
POTENTIAL FOR A LONGER TERM SNOW EVENT...RESULTING IN THE ADDITION
OF CASPER MOUNTAIN TO THE ONGOING WINTER WEATHER ADVISORIES.

AS THE AREA OF LOW PRESSURE MOVES EASTWARD...SHOWER ACTIVITY ACROSS
WESTERN WYOMING WILL WEAKEN...ESPECIALLY BY THE AFTERNOON HOURS.
EVEN WITH THIS SCENARIO... MOISTURE REMAINS OVER NORTHWESTERN
WYOMING TO CONTINUE SNOWFALL OVER THE AREA. THE AREA OF LOW PRESSURE
CAUSING THIS WIDESPREAD PRECIPITATION WILL BE ACROSS EASTERN SOUTH
DAKOTA BY EARLY MORNING HOURS OF MONDAY...WITH MOISTURE CONTINUING
TO WEAKEN ACROSS THE AREA.

HOWEVER...ANOTHER WAVE WILL IMPACT THE DESERT SOUTHWEST EARLY MONDAY
MORNING. THIS SYSTEM IS EXPECTED TO BECOME A CLOSED LOW BY MONDAY
AFTERNOON...SENDING ANOTHER ROUND OF MOISTURE ACROSS AREAS WEST OF
THE CONTINENTAL DIVIDE. AS THIS AREA OF LOW PRESSURE MOVES
EASTWARD...SHOWER ACTIVITY WILL AGAIN BECOME MORE WIDESPREAD ACROSS
CENTRAL AND WESTERN WYOMING BY MONDAY EVENING. ONGOING SHOWER
ACTIVITY WILL PERSIST THROUGH MUCH OF TUESDAY. TEMPERATURES WILL
AGAIN BE COOL ENOUGH TO PRODUCE SNOWFALL ACROSS THE HIGHER
ELEVATIONS. CURRENT FORECAST SNOWFALL TOTALS FOR THIS EVENT MAY BE
ON THE CONSERVATIVE SIDE...BUT STILL INDICATE THE POTENTIAL FOR
ANOTHER SIGNIFICANT SNOWFALL EVENT. THIS SCENARIO WILL CONTINUE TO
BE MONITORED.

.LONG TERM...WEDNESDAY THROUGH SUNDAY

INCLEMENT WEATHER WITH BELOW AVERAGE TEMPERATURES CONTINUE THROUGH
THE EXTENDED...BUT NOT NEARLY AS ACTIVE AS WHAT IS EXPECTED IN THE
SHORT TERM. GLOBAL MODELS ARE IN DECENT AGREEMENT WITH AN UPPER LOW
OVER CENTRAL NEBRASKA AT 12Z WEDNESDAY. HOWEVER MODELS DIFFER IF THE
MAIN PRECIP SHIELD WILL WRAP BACK INTO THE EASTERN FRINGES OF THE
AREA WEDNESDAY AS SUGGESTED BY THE 00Z GFS. OTHERWISE...ISOLATED
VALLEY/SCATTERED SHOWERS ARE EXPECTED WEDNESDAY WITH DAYTIME
HEATING. BY THURSDAY...MODELS SHOW AN UPPER LOW PUSHING INTO THE
SOUTHERN GREAT BASIN/DESERT SOUTHWEST...WITH A HINT OF A WEAKER
NORTHERN STREAM ENERGY OVER THE NORTHERN ROCKIES. BOTH OF THESE
FEATURES ARE EXPECTED TO SLOWLY PUSH ACROSS THE ROCKIES IN THE
FRIDAY AND SATURDAY TIME FRAME. THIS WILL CONTINUE TO GIVE CHANCES
OF MAINLY VALLEY RAIN/MOUNTAIN SNOW BOTH DAYS...BUT FOR NOW MODELS
ARE SHOWING THE MAIN ENERGY REMAINING SOUTH OF THE AREA. HAVING SAID
THAT A MOIST EASTERLY OR NORTHERLY UPSLOPE FLOW COULD ENHANCE PRECIP
CHANCES EAST OF THE DIVIDE AT TIMES FRIDAY AND/OR SATURDAY. THE 00Z
GFS TRIES TO BEGIN BUILDING IN AN UPPER RIDGE...WHILE THE ECMWF
KEEPS THE CONTINUED MEAN TROUGH AND INCLEMENT WEATHER OVER THE
FORECAST AREA.

&&

AVIATION.../18Z ISSUANCE/

WEST OF THE CONTINENTAL DIVIDE...KJAC/KRKS/KPNA/KBPI AIRPORTS

AN UPPER LOW PRESSURE SYSTEM WILL CONTINUE TO SLOWLY DRIFT EAST
ACROSS EASTERN WYOMING INTO THE CENTRAL HIGH PLAINS TODAY. A
MOIST NW FLOW BEHIND THIS SYSTEM WILL CONTINUE TO BRING LOCAL
IFR/MVFR SHRA/SHSN ACROSS THE AREA WITH SNOW LEVELS NEAR 7KFT
THROUGH 21Z. DRIER AIR AND IMPROVING CONDITIONS WILL PUSH INTO SW
WYOMING BUT GUSTY WEST WIND 20-30KT WILL CONTINUE ACROSS THE
INTERSTATE 80 CORRIDOR. NMRS MTN SHSN WILL REMAIN VCNTY AND NORTH
OF A KAFO-KPNA LINE THIS AFTN WITH MTNS MOSTLY OBSCURED ABOVE
8KFT. THIS ACTIVITY SHOULD GRADUALLY LIFT NWD TONIGHT. SOME
CLEARING MAY RESULT IN PATCHY FOG PARTIALLY OBSCURING TERRAIN IN
THE WESTERN VALLEYS TONIGHT.

EAST OF THE CONTINENTAL DIVIDE...KCPR/KCOD/KRIW/KWRL/KLND AIRPORTS

AN UPPER LOW PRESSURE SYSTEM WILL CONTINUE TO DRIFT SLOWLY EAST
ACROSS EASTERN WYOMING AND INTO THE CENTRAL PLAINS TODAY. NMRS
VALLEY RAIN AND MTN SNOW SHOWERS WILL OCCUR VCNTY AND NORTH OF A
KCPR-KLND LINE EARLY THIS MORNING WITH THIS ACTIVITY TAKING A MORE N-
S ORIENTATION ALONG AND EAST OF A KPOY-KRIW LINE 18Z-21Z. THE
MOST WIDESPREAD IFR CONDITIONS IN MODERATE RA WILL OCCUR FROM A
VCNTY KBYG-KCPR THROUGH THE DAY. MTNS MOSTLY OBSCURED...ESPECIALLY
THE BIGHORN RANGE AND CASPER MOUNTAIN DURING THE DAY. GRADUAL
IMPROVEMENT IS EXPECTED THIS EVENING WITH SOME LINGERING IFR/MVFR
SHRA MAINLY VCNTY AND NORTH OF A VCNTY KDUB-MIDWEST LINE. AREAS OF
FOG IN THE BASINS PRODUCING IFR CONDITIONS EXPECTED 09Z - 15Z.

&&

.FIRE WEATHER...

WIDESPREAD SHOWER ACTIVITY EXPECTED TODAY ACROSS THE AREA UNDER
INFLUENCING LOW PRESSURE. COOLER TEMPERATURES WILL ALSO BE COMMON
ACROSS THE AREA...WITH SNOWFALL ANTICIPATED OVER THE HIGHER
ELEVATIONS. WINTER WEATHER ADVISORIES REMAIN IN EFFECT. GUSTY WINDS
WILL REMAIN ACROSS SOUTHERN WYOMING THROUGH THE EARLY EVENING HOURS
BEFORE WEAKENING. SHOWER ACTIVITY GENERALLY REMAINS IN THE FORECAST
FOR THE NEXT FEW DAYS...WITH GUSTY WINDS RETURNING BY MONDAY
AFTERNOON.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR WYZ008-
009-022.

&&

$$

SHORT TERM...BRANHAM
LONG TERM...WM
AVIATION...C.BAKER
FIRE WEATHER...BRANHAM



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