Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 020956
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
356 AM MDT TUE SEP 2 2014

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT

WATER VAPOR SATELLITE IS CONFIRMING WHAT THE MODELS HAVE BEEN
ADVERTISING FOR A FEW DAYS...THERE IS A MUCH DRIER AIRMASS MOVING IN
AS THE FLOW TURNS MORE SOUTHWEST. HIGH PRESSURE BUILDING IN FROM THE
SOUTH WILL ALSO BRING SOME WARMER AIR WITH TEMPERATURES REBOUNDING
BACK TO NEAR 80 EAST OF THE DIVIDE. THERE WILL BE SOME GUSTS TO 30
MPH ACROSS THE SOUTH WORKING THEIR WAY INTO PORTIONS OF CENTRAL
WYOMING...LEADING TO INCREASED FIRE DANGER THIS AFTERNOON.

WEDNESDAY...MODELS ARE ADVERTISING ANOTHER UPPER LEVEL TROUGH WITH
SHARP COLD FRONT AND BAROCLINIC ZONE DROPPING SOUTH INTO
MONTANA...AT THIS TIME IT LOOKS LIKE WE WOULD NOT SEE MUCH FROM THE
FRONT UNTIL LATE WITH NOT MUCH IF ANY PRECIPITATION MAKING IT THIS
FAR SOUTH...BUT COOLER TEMPERATURES AND A WIND SHIFT TO THE NORTH IS
EXPECTED IF THIS SCENARIO ACTUALLY PLAYS OUT AS ADVERTISED.
OTHERWISE...THE WARMING TREND CONTINUES ACROSS THE SOUTH WITH STEADY
20 TO 30 KNOT SOUTHWESTERLIES AND CONTINUED FIRE WEATHER CONCERNS AS
MIN RHS ARE EXPECTED TO DROP INTO THE TEENS AGAIN ON WEDNESDAY
AFTERNOON.

THURSDAY...MUCH COOLER BEHIND THE FRONT WITH SOME CLOUD COVER
HANGING AROUND ALONG AND EAST OF THE DIVIDE. DRY SOUTHWESTERLY FLOW
REMAINS ACROSS THE WEST AND SOUTH...THOUGH WINDS WILL NOT BE AS
STRONG AND THE TEMPERATURE CHANGES WILL NOT BE AS SHARP.

.LONG TERM...FRIDAY THROUGH TUESDAY

A LITTLE WARMER ON FRIDAY WITH ISOLATED SHOWERS AND STORMS FOR
SOUTHWEST WY IN THE AFTERNOON AND EVENING WHERE BETTER INSTABILITY
WILL OCCUR. DRY ELSEWHERE AS AIRMASS LOOKS TO BE STABLE WITH VERY
ISOLATED ACTIVITY. WEST SOUTHWEST FLOW ALOFT FOR SATURDAY AND
SUNDAY WITH WEAK DISTURBANCES IN THE FLOW PER THE GFS AND ECMWF
MODELS. ISOLATED TO WIDELY SCATTERED AFTERNOON AND EVENING SHOWERS
AND STORMS BOTH DAYS. HIGH TEMPS TO WARM A FEW DEGREES SATURDAY
AND SUNDAY. MONDAY LOOKS TO BE MORE OF THE SAME WITH ISOLATED
SHOWERS AND STORMS. EXPECT SOME BREEZY AREAS MONDAY AND SEASONABLY
WARM. THE GFS AND ECMWF DIFFER NEXT TUESDAY WITH THE STRENGTH AND
MOVEMENT OF A WEATHER SYSTEM ACROSS THE NORTHERN ROCKIES. A BRISK
COLD FRONT IS FORECAST BY BOTH MODELS TO MOVE THROUGH WY NEXT TUE
WITH THE GFS BEING THE COLDER MODEL SOLUTION FOR HIGH TEMPS. HAVE
PLAYED HIGHS 10 TO 15 DEGREES COOLER OVER THE NORTH AND 8 TO 12
DEGREES COOLER OVER THE SOUTH. PRECIP CHANCE LOOKS HIGHER ON THE
GFS VERSUS THE ECMWF. FOR NOW WILL PLAY A BLEND AND HAVE ISOLATED
TO WIDELY SCATTERED SHOWERS/STORMS NEXT TUE.

&&

.AVIATION.../12Z ISSUANCE/

A LAST IN A SERIES OF UPPER LEVEL DISTURBANCES IN NW FLOW WILL RACE
SE INTO NW WYOMING THIS MORNING AND INTO THE HIGH PLAINS LATE THIS
AFTERNOON.   AREAS OF MVFR/IFR CIGS WITH SCT -SHRA...SNOW LEVELS
NEAR 9.5KFT WITH FRQT MTN OBSCURATIONS ...WILL SPREAD ACROSS
NORTHERN WYOMING FROM YELLOWSTONE NATIONAL PARK TO A VCNTY AND NORTH
OF KCOD-KBYG LINE 09Z-15Z.  MOST OF THIS ACTIVITY WILL PUSH FROM
VCNTY OF THE BIGHORN RANGE AND EASTWARD BY EARLY AFTERNOON.  SOME OF
THIS SHOWER ACTIVITY MAY REACH AS FAR AS KCPR IN THE LATE MORNING
AND AFTERNOON.  W-NW WIND AT 15-25KT AND MAINLY SKC CONDITIONS WILL
PREVAIL ACROSS THE SOUTHERN THIRD OF THE AREA IN THE AFTERNOON.

SKC CONDITIONS WITH DIMINISHING WIND...PATCHY FOG IN THE WESTERN
VALLEYS...WILL PREVAIL MONDAY NIGHT.

&&

.FIRE WEATHER...

...RED FLAG CONDITIONS EXPECTED ACROSS PORTIONS OF RAWLINS...CODY
AND CASPER DISPATCH THIS AFTERNOON AND AGAIN ON WEDNESDAY...

MUCH WARMER AND DRIER TODAY AND TOMORROW...IN ADDITION TO WINDIER.
VERY LOW RELATIVE HUMIDITY AND STRONG GUSTY WINDS WILL DEVELOP
ACROSS THE SOUTHWEST AND CENTRAL PORTIONS OF WYOMING AFTER NOON ON
CONTINUING UNTIL AROUND 8 PM MDT. THE VERY LOW RELATIVE HUMIDITY AND
STRONG GUSTY WINDS WILL REDEVELOP AFTER NOON ON WEDNESDAY CONTINUING
UNTIL AROUND 8 PM MDT WEDNESDAY EVENING...AT WHICH TIME A DRY COLD
FRONT WILL BE DROPPING INTO NORTHERN WYOMING...SHIFTING THE WINDS TO
THE NORTH WITH WINDS REMAINING IN THE 20 TO 30 MPH RANGE WITH GUSTS
OVER 45MPH IN AREAS PRONE TO NORTHERLY WIND. RED FLAG WARNING IS IN
EFFECT FROM NOON TO 8 PM MDT TODAY FOR WIND AND LOW RELATIVE
HUMIDITY FOR FIRE WEATHER ZONES 279...280... 283 AND 289. RED FLAG
WARNING AGAIN IN EFFECT FROM NOON TO 8 PM MDT WEDNESDAY FOR WIND AND
LOW RELATIVE HUMIDITY FOR FIRE WEATHER ZONES 279...280...283 AND
289.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...

RED FLAG WARNING FROM NOON TODAY TO 8 PM MDT THIS EVENING
WYZ279-280-283-289.

RED FLAG WARNING FROM NOON TO 8 PM MDT WEDNESDAY
WYZ279-280-283-289.

&&

$$

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






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