Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 062033
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
233 PM MDT FRI MAY 6 2016

.SHORT TERM...TONIGHT THROUGH SATURDAY

FLOOD WATCH IN EFFECT.  WINTER STORM WARNING FOR THE WIND RIVER
AND ABSAROKA MOUNTAINS ABOVE 8500 FEET IN EFFECT.

A LARGE CLOSED LOW PRESSURE CENTER OVER THE GREAT BASIN IS DEEPENING
AND HAS PRODUCED STRONG NORTHEAST LOW LEVEL FLOW ACROSS WYOMING.
ALOFT A SOUTHEAST FLOW CONTINUES TO SPREAD MOISTURE AND INSTABILITY
OVER SOUTHERN AND CENTRAL AREAS.  SHOWERS...MAINLY RAIN BELOW 9000
FEET WITH SNOW ABOVE WILL INCREASE BECOMING QUITE WIDESPREAD OVER
NIGHT.  EMBEDDED THUNDERSTORMS WITH HAIL...HEAVY RAIN AND STRONG
WIND GUSTS ARE POSSIBLE THROUGH THIS EVENING. TEMPERATURES WILL BE
COLD WITH ELEVATED RELATIVE HUMIDITY AND LOW MIXING HEIGHTS. RAIN
WITH MOUNTAIN SNOW WILL CONTINUE THROUGH SUNDAY MORNING. ALONG THE
CONTINENTAL DIVIDE SNOW OF 20 TO 30 INCHES IS POSSIBLE.
SIGNIFICANT RAINFALL OF 2 TO LOCALLY 5 INCHES IS EXPECTED IN THE
MOUNTAINS BELOW 9000 FEET.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY

COLD RAIN AND SNOW WILL CONTINUE SATURDAY NIGHT WITH COLDER
TEMPERATURES.  PRECIPITATION WILL TAPER OFF SUNDAY MORNING BUT
LIGHTER PRECIPITATION IS STILL EXPECTED WITH DECREASING COVERAGE
THROUGH THE DAY AND SUNDAY EVENING. NORTH NORTHWEST FLOW SETS UP
WITH A SERIES OF LOW PRESSURE TROUGHS MOVING SOUTH SOUTHEAST FROM
WESTERN MONTANA OVER EASTER IDAHO AND WESTERN WYOMING. THIS KEEPS
SOME SHOWERS AND POSSIBLE AFTERNOON AND EVENING THUNDERSTORMS
OVER THE AREA ESPECIALLY IN THE WESTERN AND NORTHERN MOUNTAINS
THROUGH FRIDAY. GRADUAL WARMING IS EXPECTED. MODELS NOT VERY
CONSISTENT THROUGH THE EXTENDED EITHER RUN TO RUN OR AMONG THE
VARIOUS EXTENDED MODELS. THIS DECREASES CONFIDENCE THROUGH THE
PERIOD.

&&

.AVIATION.../00Z ISSUANCE/

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

UPPER LOW ALONG THE SOUTHERN CALIFORNIA COAST WILL GRADUALLY TRACK
ONSHORE AND SPREAD MOISTURE NORTH ACROSS THE FORECAST AREA THROUGH
THIS EVENING. THE SHORTWAVE OVER NORTHEAST UTAH...SOUTHWEST
WYOMING AND SOUTHEAST IDAHO WILL MAKE ITS WAY NORTH THROUGH THIS
EVENING. THE COLD FRONT HAS DROPPED SOUTH ACROSS WYOMING. THIS
COMBINATION WILL SET THE STAGE FOR SHOWERS AND THUNDERSTORMS...SOME
POSSIBLY STRONG. A SECOND BAND OF THUNDERSTORMS WILL CONTINUE TO
TRACK NORTH ACROSS FAR SOUTHWEST AND WESTERN WYOMING THIS AFTERNOON
AND EVENING WITH LOCAL IFR CONDITIONS. AFTER 23Z/TODAY...ADDITIONAL
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO ERUPT FOR THE REMAINDER
OF THE AFTERNOON AND EARLY EVENING. ANY THUNDERSTORMS WILL LIKELY
PRODUCE SMALL HAIL. MOISTURE DEEPENS THROUGH THE EVENING HOURS.
EXPECT WIDESPREAD MOUNTAIN OBSCURATIONS AFTER ABOUT 00Z/SATURDAY.
HAVE KEPT LOW END VFR AT KRKS...KBPI...AND KPNA BETWEEN 00Z-
06Z/SATURDAY...ALTHOUGH MVFR WOULD BE A DISTINCT POSSIBLITY.
SURFACE WIND FROM THE EAST- NORTHEAST TO EAST- SOUTHEAST OF
12-22KTS...HIGHER AT KRKS...WILL PROVIDE FAVORABLE SHEAR PROFILE
DURING THE REMAINDER OF THE AFTERNOON AND EARLY EVENING ACROSS
SOUTHWEST WYOMING. HEAVIER PRECIPITATION FROM 00Z-12Z/SATURDAY
WILL BE SNOW ABOVE 9K FT MSL...LOWER DURING HEAVIER PRECIPITATION.
BETTER CHANCE FOR MVFR CEILINGS/VISIBILITY WILL COME BETWEEN 06Z-
12Z/SATURDAY BECAUSE OF BETTER DYNAMICS AND DEEPER MOISTURE. KJAC
WILL BE THE LEAST LIKELY LOCATION TO SEE MVFR CEILINGS AS UPPER
FLOW IS NOT AS FAVORABLE THERE.

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

SMOKE FROM THE LARGE FIRE IN ALBERTA WILL DISSIPATE THROUGH EARLY
THIS EVENING AS NORTHERLY WINDS BRINGING IN THE SMOKE WORK AGAINST
THE CLEANSING OF THE ATMOSPHERE FROM THE ANTICIPATED RAINFALL
ACROSS NORTHERN WYOMING. UPPER LOW WILL GRADUALLY TRACK ONSHORE
ACROSS SOUTHERN CALIFORNIA THIS EVENING WHILE CONTINUING TO
SPREAD MOISTURE NORTH ACROSS THE EASTERN GREAT BASIN INTO WYOMING.
THE COLD FRONT RESPONSIBLE FOR THE NORTH WINDS HAS PUSHED SOUTH
FROM MONTANA THIS MORNING. THESE POST FRONTAL WINDS WILL CONTINUE
TO STIR NORTHERLY WINDS OF UP TO 25 TO 40 MPH ACROSS THE BIG HORN
BASIN THROUGH THIS EVENING. THE WIND WILL INCREASE THIS AFTERNOON
AT ALL TERMINALS AS PRESSURE GRADIENT TIGHTENS. BEST CHANCE FOR
STRONG CONVECTION WILL BE TO THE SOUTH OF A KRIW- KCPR LINE AFTER
22Z/TODAY. MOISTURE DEEPENS AND MODEL SOUNDINGS SHOW ATMOSPHERE
QUICKLY SATURATING BETWEEN 23Z/TODAY AND
03Z/SATURDAY...PARTICULARLY AT KLND...KRIW...AND KCPR. EXPECT
WIDESPREAD MVFR WITH LOCALIZED IFR CONDITIONS NEAR THE FOOTHILLS.
MOUNTAINS WILL BE OBSCURED THROUGH THE REMAINDER OF THE FORECAST
PERIOD. IFR/MVFR CEILINGS/VISIBILITY WILL BECOME MORE WIDESPREAD
BETWEEN 06Z-12Z/SATURDAY. PRECIPITATION AMOUNTS 0.50 INCHES IN
6-HOURS...DYNAMICS ARE FAVORABLE...AND UPSLOPE FLOW WILL ENHANCE
PRECIPITATION PRODUCTION.

&&

.FIRE WEATHER...

A LARGE CLOSED LOW PRESSURE CENTER OVER THE GREAT BASIN IS DEEPENING
AND HAS PRODUCED STRONG NORTHEAST LOW LEVEL FLOW ACROSS WYOMING.
ALOFT A SOUTHEAST FLOW CONTINUES TO SPREAD MOISTURE AND INSTABILITY
OVER SOUTHERN AND CENTRAL AREAS.  SHOWERS...MAINLY RAIN BELOW 9000
FEET WITH SNOW ABOVE WILL INCREASE BECOMING QUITE WIDESPREAD OVER
NIGHT.  EMBEDDED THUNDERSTORMS WITH HAIL...HEAVY RAIN AND STRONG
WIND GUSTS ARE POSSIBLE THROUGH THIS EVENING. TEMPERATURES WILL BE
COLD WITH ELEVATED RELATIVE HUMIDITY AND LOW MIXING HEIGHTS. SOME OF
THE WINDIER AREAS MAY SEE LOW END GOOD SMOKE DISPERSAL BUT OVERALL
POOR SMOKE DISPERSAL IS EXPECTED.  RAIN WITH MOUNTAIN SNOW WILL
CONTINUE THROUGH SUNDAY MORNING. ALONG THE CONTINENTAL DIVIDE
SNOW OF 20 TO 30 INCHES IS POSSIBLE.  SIGNIFICANT RAINFALL OF 2
TO LOCALLY 5 INCHES IS EXPECTED IN THE MOUNTAINS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 6 AM MDT SUNDAY FOR WYZ002-014-015.

FLOOD WATCH FROM SATURDAY MORNING THROUGH SUNDAY AFTERNOON FOR
WYZ007-017-018.

&&

$$

SHORT TERM...C.BAKER
LONG TERM...C.BAKER
AVIATION...LIPSON
WEATHER...C.BAKER



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