Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 290909
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
309 AM MDT SUN MAR 29 2015

.SHORT TERM...SUNDAY THROUGH TUESDAY NIGHT

IT IS STILL A BIT WINDY AFTER MIDNIGHT SUNDAY MORNING AS A LOW WINDS
UP OVER THE WESTERN DAKOTAS...ESPECIALLY FROM THE BIG HORN BASIN AND
EASTWARD. THE REST OF THE NIGHT SHOULD FEATURE GRADUALLY DECREASING
WINDS AS THE LOW AND FRONT MOVE AWAY TO THE EAST AND THE PRESSURE
GRADIENT RELAXES THROUGH THE NIGHT. RIDGING WILL THEN BUILD ACROSS
THE AREA TODAY AND BRING A DRY DAY WITH ONLY A FEW PASSING MID TO
HIGH LEVEL CLOUDS. TEMPERATURES WILL BE COOLER BEHIND THE
FRONT...BUT WILL REMAIN ABOVE NORMAL FOR MOST AREAS. WITH LESS OF A
PRESSURE GRADIENT...ONLY SOME BREEZES IN THE FAVORED AREAS AND EVEN
THESE WILL NOT BE VERY STRONG.

MAINLY DRY WEATHER LOOKS TO CONTINUE INTO MONDAY AS WELL WITH
RIDGING HOLDING OVER THE AREA. WITH THICKNESSES RISING A BIT LOOK
FOR TEMPERATURES TO BEGIN ANOTHER WARMING TREND ONCE AGAIN. ONCE
AGAIN...THERE WILL BE SOME BREEZES ACROSS THE FAVORED LOCATIONS
NOTHING UNUSUAL FOR WYOMING IN THE LATTER PORTION OF MARCH.

THE NEXT WEATHER MAKER IN THE FORM OF A COLD FRONT AND ASSOCIATED
SHORTWAVE WILL MOVE TOWARD THE STATE FOR TUESDAY. THE MODELS ARE
CONSISTENT IN KEEPING THE AREA DRY IN THE MORNING SO WE CONTINUED
THIS. WITH INCREASING SOUTHWEST FLOW AND A TIGHTENING PRESSURE
GRADIENT AHEAD OF THE FRONT...TEMPERATURES WILL SPIKE UPWARD ONCE
AGAIN. WITH THE INCREASING WIND...FIRE DANGER MAY ONCE AGAIN REAR
ITS UGLY HEAD FOR TUESDAY AFTERNOON. STAY TUNED ON THAT. AS FOR
PRECIPITATION...THE BEST CHANCE WOULD BE WEST OF THE DIVIDE WITH
SOME UPSLOPE FLOW AND IN THE NORTH WHERE THE BETTER DYNAMICS WILL
BE. ELSEWHERE...DOWNSLOPING FLOW MAY KEEP THINGS ON THE DRY SIDE.

.LONG TERM...WEDNESDAY THROUGH SUNDAY

A COLD FRONT BLOWS ACROSS THE AREA WEDNESDAY WITH A GUSTY WIND DAY
IN STORE WITH COOLER HIGH TEMPS. THE GFS AND ECMWF ARE FAIRLY CLOSE
WITH TIMING AND IMPACT. SCATTERED RAIN AND SNOW SHOWERS OVER THE
NORTH HALF OF THE REGION...MAINLY ALONG AND NORTH OF A LINE FROM
JACKSON TO MIDWEST. THE GFS MODEL HAS A SECOND WEATHER SYSTEM
QUICKLY MOVING TOWARD THE AREA LATE WED NIGHT AND THEN MOVES IT
THROUGH THURSDAY AND THURS NIGHT. COLDER AIR WITH THIS SYSTEM AND
THE GFS 700MB TEMPS SUPPORT MAINLY SNOW SHOWERS THURSDAY INTO THURS
NIGHT. THE ECMWF MODEL IS ALSO SUPPORTING THIS PATTERN FOR THURS
INTO THURS NIGHT WITH COLD 700MB TEMPS. SNOW THAT DOES FALL DURING
THE DAY THURS WOULD MELT FOR THE MOST PART DUE TO WARM GROUND...THEN
COULD ACCUMULATE THURS NIGHT. COULD SEE SOME LINGERING SNOW SHOWERS
FRI MORNING FROM ROCK SPRINGS TO CASPER...ENDING BY 18Z. THE ECMWF
MODEL HAS UNSETTLED WEATHER THROUGH MOST OF FRI AS IT IS SLOWER WITH
THE SYSTEM EXITING THE REGION ON FRI. THE 00Z GEM IS ALSO SLOWER AND
MORE LIKE THE ECMWF MODEL FRIDAY. WILL KEEP SOME PRECIP IN THE SOUTH
AND SOUTHEAST ZONES FRI MORNING...THEN LOW POPS IN THE MOUNTAINS
DURING THE DAY FRIDAY. SATURDAY LOOKS DRY AND MILDER. GFS MODEL
BRINGS ANOTHER SYSTEM INTO WESTERN WY NEXT SUNDAY AND THE ECMWF
MODEL IS ALSO SHOWING A DISTURBANCE IMPACTING THE WEST NEXT SUNDAY.
WILL PUT IN LOW POPS FOR THE WEST AND SEE HOW THINGS LOOK TONIGHT.
COLDER HIGH TEMPS FOR THURSDAY AND FRIDAY...MAY NEED TO GO EVEN
COLDER IN TIME IF THIS PATTERN DOES OCCUR AS THE MODELS DEPICT.
THEN MILDER SATURDAY AND NEXT SUNDAY.

&&

.AVIATION.../12Z ISSUANCE/

A THIN SMOKE LAYER FROM A LARGE WILDFIRE IN EASTERN MONTANA MAY
LINGER VCNTY AND EAST OF INTERSTATE 25 INCLUDING VCNTY KCPR THROUGH
12Z.  OTHERWISE...SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD IN
FROM THE WEST OVERNIGHT WITH DIMINISHING WIND AND CLEARING SKIES.  A
RIDGE OF HIGH PRESSURE WILL BRING GENERALLY LIGHT WIND...WITH SOME
MID AND HIGH CLOUDS ACROSS NORTHERN WYOMING SUNDAY AFTERNOON AND
EVENING...PREVAILING VFR CONDITIONS THROUGH 12Z MONDAY.

&&

.FIRE WEATHER...

AS A COLD FRONT AND ASSOCIATED LOW PRESSURE MOVE AWAY TO THE
EAST...WIND SHOULD DECREASE EARLY THIS MORNING. WITH COOLER
TEMPERATURES AND LIGHTER WIND TODAY...NO FIRE WEATHER HIGHLIGHTS ARE
ANTICIPATED TODAY. WIND SHOULD REMAIN LIGHT TO MODERATE INTO MONDAY
AS WELL. ANOTHER COLD FRONT APPROACHING FROM THE WEST FOR TUESDAY
COULD BRING ELEVATED FIRE CONDITIONS ON TUESDAY AFTERNOON IN ZONES
WHERE FUELS ARE CRITICAL.

&&

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

&&

$$

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



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