Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 270911
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
311 AM MDT FRI MAR 27 2015

.SHORT TERM...FRIDAY THROUGH SUNDAY NIGHT

A WEAK SHORTWAVE PASSING THROUGH THE AREA LATE THURSDAY NIGHT HAS
BEEN BRINGING SOME GUSTY WINDS TO PORTIONS OF THE AREA. THESE SHOULD
DECREASE THROUGH THE NIGHT AND INTO TOMORROW MORNING AS THE
SHORTWAVE MOVES AWAY AND THE PRESSURE GRADIENT RELAXES AS A RIDGE
BUILDS OVER THE AREA. THE RESULT WILL BE A MAINLY QUIET WEATHER DAY
WITH SOME PASSING MID AND HIGH LEVEL CLOUDS. TEMPERATURES WILL BE
QUITE WARM WITH SOME LOCATIONS RISING INTO THE 70S.

THINGS GET A BIT MORE ACTIVE FOR SATURDAY AS ANOTHER SHORTWAVE AND
ASSOCIATED COLD FRONT MOVES ACROSS THE AREA. HOWEVER...IT WILL NOT
BE IN THE FORM OF MOISTURE. MOST OF THE MOISTURE AND DYNAMICS WILL
MOVE BY TO THE NORTH OVER MONTANA. THERE COULD BE A FEW SHOWERS
ACROSS THE NORTH...BUT THIS WOULD BE THE EXCEPTION RATHER THAN THE
RULE. IT WILL BE IN FORM OF WIND. THE MODELS SHOW A 90 KNOT JET
STREAK APPROACHING THE NORTHWESTERN PORTION OF THE STATE. THIS PUTS
MUCH OF THE STATE IN THE RIGHT FRONT QUAD AND THEREFORE SOME
INCREASE IN UPPER LEVEL DIVERGENCE AND DOWNWARD MOMENTUM.  700
MILLIBAR WINDS INCREASE TO 50 TO 60 KNOTS ACROSS THE FAVORED AREAS
OF THE ABSAROKAS AND CODY FOOTHILLS. IT IS BORDERLINE FOR HIGH WIND
THERE ON SATURDAY SO WE WILL LET THE DAY CREW MAKE THE CALL. ANOTHER
AREA OF CONCERN IS NORTHERN JOHNSON COUNTY WHICH IS FAVORED IN
NORTHWEST FLOW AFTER COLD FRONT PASSAGES. OF MORE CONCERN IN THE
RISK FOR CRITICAL FIRE WEATHER. WITH LOW RELATIVE HUMIDITY EXPECTED
ACROSS MUCH OF THE AREA WITH CRITICAL FUELS...WE WILL HOIST A FIRE
WEATHER WATCH ACROSS THE LOWER ELEVATIONS ZONES WITH CRITICAL FUELS.
IT WILL BE QUITE WARM AS WELL WITH MANY LOWER ELEVATIONS AGAIN
SEEING HIGH TEMPERATURES INTO THE 70S.

CONDITIONS WILL ONCE AGAIN CALM FOR SUNDAY AS THE SYSTEM MOVES AWAY
AND RIDGING MOVES BACK ACROSS THE STATE. TEMPERATURES WILL FALL
SOMEWHAT BEHIND THE FRONT...AROUND 10 DEGREES FOR MANY AREAS BUT
THIS STILL PUTS MOST AREAS ABOVE SEASONAL NORMALS.

.LONG TERM...MONDAY THROUGH FRIDAY

DRY AND WARM CONDITIONS ARE EXPECTED MONDAY UNDER A FLAT UPPER
RIDGE. A COMPACT...BUT STOUT UPPER LOW WILL PUSH EAST ACROSS THE
EXTREME NORTHERN ROCKIES TUESDAY...WITH THE ASSOCIATED PACIFIC COLD
FRONT SWEEPING EAST ACROSS THE FORECAST AREA TUESDAY AFTERNOON AND
EVENING. ALTHOUGH THIS SYSTEM COULD BRING SOME CONVECTION ESPECIALLY
OVER THE NORTHWEST...THE MAIN IMPACT WILL BE EXTREME FIRE WEATHER
CONDITIONS TUESDAY AFTERNOON AND EVENING...WHERE FUELS ARE
CONSIDERED CRITICAL.

A COOLER AND MAINLY DRY DAY IS EXPECTED WEDNESDAY IN WAKE OF THE
PACIFIC COLD FRONT. THERE COULD STILL BE SOME FIRE WEATHER
CONCERNS...AS WINDS WILL REMAIN BREEZY...BUT COOLER CONDITIONS
SHOULD ALLOW FOR SLIGHTLY HIGHER RH.

GLOBAL MODELS SHOW A SHORTWAVE TROUGH DIVING SOUTHEAST INTO THE
INTERMOUNTAIN WEST THURSDAY...THEN INTO THE FOUR CORNERS REGION
THURSDAY NIGHT THEN EAST INTO THE CENTRAL PLAINS FRIDAY. THE CURRENT
PROJECTED TRACK OF THIS SYSTEM WOULD GIVE THE AREA A BETTER CHANCES
OF PRECIPITATION THAN EITHER SYSTEM ON SATURDAY OR TUESDAY. BOTH THE
00Z OPERATIONAL ECMWF AND GFS SOLUTIONS SHOW SOME UPSLOPE FLOW
DEVELOPING THURSDAY INTO THURSDAY NIGHT. WILL BROAD BRUSH SLIGHT
VALLEY/CHANCE MOUNTAIN POPS THURSDAY AND FRIDAY FOR NOW...AS TIMING
AND CONFIDENCE INCREASES.

WELL ABOVE AVERAGE TEMPERATURES ARE EXPECTED MONDAY AND
TUESDAY...WITH SEASONAL TEMPERATURES WEDNESDAY...WITH THE POTENTIAL
OF BELOW AVERAGE ON THURSDAY AND/OR FRIDAY.

&&

.AVIATION.../12Z ISSUANCE/

VFR CONDITIONS WILL PREVAIL ACROSS THE AREA THROUGH 12Z SATURDAY.
GUSTY W-NW WINDS ALONG THE EAST SLOPES OF THE DIVIDE...VICINITY
KCOD-KDUB-KRIW...WILL MOSTLY DIMINISH BY 15Z.

WINDS WILL INCREASE ACROSS THE WIND CORRIDOR...VICINITY 50SM NE
KRKS-KCPR...AND ALONG THE LEE SLOPES OF THE DIVIDE AFTER 06Z
SATURDAY AHEAD OF AN APPROACHING COLD FRONT.  THE COLD FRONT WILL
PUSH EAST ACROSS THE AREA LATE SATURDAY MORNING AND AFTERNOON.

&&

.FIRE WEATHER...

EXPECT ANOTHER WARM AND DRY DAY TODAY. HOWEVER...WINDS SHOULD
DECREASE THROUGH THE DAY SO CRITICAL FIRE WEATHER IS NOT EXPECTED.
ON SATURDAY...A COLD FRONT AND UPPER LEVEL DISTURBANCE WILL MOVE
ACROSS THE AREA. THE COMBINATION OF GUSTY WINDS AND LOW RELATIVE
HUMIDITY MAY BRING CRITICAL FIRE WEATHER TO LOWER ELEVATION ZONES
WITH CRITICAL FUELS. CONDITIONS SHOULD IMPROVE FOR SUNDAY WITH
COOLER TEMPERATURES AND LESS WIND.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
FIRE WEATHER WATCH FROM SATURDAY AFTERNOON THROUGH SATURDAY
EVENING WYZ280-281-283.

&&

$$

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






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