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000
FXUS65 KRIW 140946
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
346 AM MDT FRI MAR 14 2014

.SHORT TERM...FRIDAY THROUGH SUNDAY NIGHT

MAINLY QUIET WEATHER DOMINATES ACROSS THE AREA THIS MORNING AS A
RIDGE OF HIGH PRESSURE HOLDS OVER THE AREA. HOWEVER...THE WEATHER
WILL BECOME A BIT MORE ACTIVE LATE TODAY AND TONIGHT AS A PACIFIC
SYSTEM MOVES TOWARD THE STATE. THE MODELS CONTINUE TO HAVE SOME
TIMING DIFFERENCES WITH THE GFS THE FASTER MODELS AND BRINGING SOME
PRECIPITATION TO THE WEST LATER IN THE AFTERNOON AND THE NAM KEEPING
THINGS UNTIL AFTER 00Z. FOR NOW...WE COMPROMISED AND REMOVED POPS
BEFORE 21Z AND THEN INCREMENTALLY INCREASING THEM INTO THE EVENING
ACROSS THE WEST. MEANWHILE...EXPECT ANOTHER DRY DAY EAST OF THE
DIVIDE WITH ABOVE NORMAL TEMPERATURES. THERE WILL BE SOME BREEZES IN
THE USUAL BREEZIER SPOTS BUT NOTHING UNUSUAL FOR WYOMING IN MARCH.

THE MODEL DIFFERENCES CONTINUE TONIGHT AS THE SYSTEM PRESSES EAST OF
THE DIVIDE. THE NAM CONTINUES TO BE THE DRIER MODEL WITH AREAS EAST
OF THE DIVIDE STAYING LARGELY DRY EXCEPT FOR THE MOUNTAINS AND
EXTREME EASTERN AREAS WITH DOWNSLOPING FLOW PREDOMINATING.
MEANWHILE...THE GFS IS WETTER...ESPECIALLY ACROSS PORTIONS OF
JOHNSON COUNTY. IT ALSO PUTS A BAND OF SNOW ACROSS PORTIONS OF
FREMONT COUNTY. THE MODELS ARE NOTORIOUSLY BAD WITH PINPOINTING
THESE BANDS HOWEVER. THERE IS SOME DECENT UPPER LEVEL FORCING WITH
THE AREA UNDER THE LEFT FRONT QUAD OF A PASSING JET STREAK LATER
FRIDAY NIGHT INTO EARLY SATURDAY. WITH THE UNCERTAINTY WE MADE FEW
CHANGES.

THE STEADY PRECIPITATION SHOULD END SATURDAY MORNING. THE MAIN
CONCERN THEN TURNS TO THE POSSIBILITY OF HIGH WIND. THE MOST FAVORED
AREA WOULD BE NORTHERN JOHNSON COUNTY WITH THE FAVORED STRONG
NORTHWEST POST FRONTAL PASSAGE FLOW. THE NAM IS ESPECIALLY BULLISH
WITH 50 TO 60 KNOT 700 MILLIBAR WINDS ON SATURDAY MORNING AND INTO
THE MIDDAY. THE GFS HAS DECENT WIND AS WELL. STILL LOOKS BORDERLINE
THROUGH SO WE WILL LET THE DAYSHIFT MAKE THE DECISION ON ANY
HIGHLIGHTS. MEANWHILE...EXPECT A BREEZY AND COOLER DAY ACROSS MOST
OF THE COUNTY WARNING AREA...NOT OVERLY COLD BUT STILL A BIT OF A
CHANGE GIVEN THE RECENT FEW MILD DAYS.

MAINLY DRY WEATHER THEN LOOKS TO DOMINATE INTO SUNDAY NIGHT AS
RIDGING BUILDS ACROSS WYOMING. TEMPERATURES SHOULD REBOUND NICELY ON
SUNDAY FROM THE CHILLY SATURDAY READINGS. HOWEVER...WITH THE
PRESSURE GRADIENT TIGHTENING ACROSS THE STATE WITH AN APPROACHING
SYSTEM FROM THE NORTHWEST IT WILL BECOME BREEZY AT TIMES ONCE AGAIN.
MODELS ARE INDICATING STRONGER WINDS ACROSS SOME FAVORED AREAS
DOWNWIND OF THE ABSAROKAS THAT WILL HAVE TO BE WATCHED. ANY
PRECIPITATION FROM THE AFOREMENTIONED SYSTEM SHOULD HOLD OFF UNTIL
MONDAY.

.LONG TERM...MONDAY THROUGH FRIDAY

THE GFS AND ECMWF MODELS ARE MAINTAINING A RAIN AND SNOW EVENT FOR
MUCH OF THE AREA STARTING MONDAY MORNING IN THE NW. THEN THE PRECIP
SLIDES SOUTH SOUTHEAST MONDAY AFTERNOON THROUGH MONDAY NIGHT. GFS
MODEL IS FASTER WITH THE SYSTEM SPEED THAN THE ECMWF...WHICH IS
ABOUT 6 HOURS SLOWER. BOTTOM LINE IS THAT IT WILL BE UNSETTLED. THEN
TUESDAY WILL SEE A DECREASE IN PRECIP FROM NORTHWEST TO SOUTHEAST.
THERE IS A SECONDARY SYSTEM THAT MAY IMPACT THE REGION TUESDAY NIGHT
INTO WED MORNING. THE ECMWF MODEL IS SHOWING THIS WHILE THE GFS
MODEL IS QUICKER WITH THIS FEATURE AND ITS IMPACT IS LESS TO THE
AREA. HAVE ADJUSTED FORECAST MONDAY THROUGH WEDNESDAY MORNING
LEANING MORE TOWARD THE ECMWF SPEED OF THE SYSTEMS. THE WEATHER
IMPROVES WED AFTERNOON AND HAVE GONE DRY FROM 18Z ONWARD. THE DRY
WEATHER EXTENDS THROUGH THURSDAY PER BOTH MODELS. THEN SOME
DIFFERENCES SHOW UP AGAIN THURSDAY NIGHT THROUGH FRIDAY. THE GFS IS
SLOWER WITH BRINGING MOISTURE INTO THE WEST THURS NIGHT AND FRIDAY
AS IS BASICALLY DRY. THE ECMWF IS INDICATING SOME MOISTURE INTO
NW WY THURSDAY NIGHT THROUGH FRIDAY FOR MAINLY LIGHT PRECIP. THIS
IS ALL RELATED TO THE MODELS HAVING ISSUES WITH THE WEATHER
PATTERN OFF THE NW U.S. COAST DURING THIS TIMEFRAME. FOR NOW JUST
LOW PRECIP CHANCE IN THE NW WY MOUNTAINS THURS NIGHT THROUGH
FRIDAY. AS FOR TEMPS...A MILD DAY AHEAD OF THE SYSTEM MONDAY EAST
AND SOUTH WITH MORNING HIGHS IN THE WEST AND NORTH AS THE COLD AIR
ARRIVES THERE FIRST. COLDER DAY FOR TUESDAY...THEN MODERATING
HIGHS WED THROUGH FRI.

&&

.AVIATION.../12Z ISSUANCE/

WEST OF THE DIVIDE...KJAC/KPNA/KBPI/KRKS ROUTES

VFR CONDITIONS WILL PREVAIL ACROSS THE AREA THROUGH 00Z SATURDAY.  A
QUICK MOVING DISTURBANCE WILL BRING RAPIDLY DETERIORATING
CONDITIONS...MTN OBSCURATIONS FROM NW-SE ACROSS THE AREA FRIDAY
EVENING WITH PREVAILING IFR/MVFR CONDITIONS EXPECTED VCNTY AND NORTH
OF A KAFO-KPNA LINE 02Z-08Z SATURDAY.  THIS WILL BE FOLLOWED BY
RAPIDLY IMPROVING CONDITIONS NW-SE 08Z-12Z SATURDAY.

EAST OF THE DIVIDE...KCPR/KCOD/KLND/KRIW/KWRL ROUTES

VFR CONDITIONS WILL PREVAIL THROUGH 03Z SATURDAY.  A LEE SIDE
SURFACE TROUGH WILL INTENSIFY THROUGH THE DAY SATURDAY AHEAD OF AN
APPROACHING COLD FRONT WITH SW WINDS INCREASING TO 20-30KT VCNTY
50NE KRKS-KCPR.  THE COLD FRONT WILL PUSH NW-SE ACROSS THE AREA
03Z-08Z SATURDAY WITH SCT-NMRS MVFR/IFR -SHSN EXPECTED VCNTY AND
EAST OF A KCOD-KWRL-KCPR LINE...WITH SHSN LESS NUMEROUS TO THE SOUTH
AND WEST.  AREAS OF STRONG NW WINDS AND RAPID CLEARING WILL OCCUR
08Z-12Z SATURDAY...ESPECIALLY IN FAVORED NW WIND CORRIDORS VCNTY AND
NORTH OF INTERSTATE 90 AND VCNTY KRIW.

&&

.FIRE WEATHER...

EXPECT MAINLY DRY WEATHER TODAY WITH A GUSTY WIND DEVELOPING IN
THE FAVORED AREAS. A PACIFIC SYSTEM WILL MOVE INTO WESTERN WYOMING
LATE TODAY AND BRING MAINLY LIGHT SNOW FRIDAY NIGHT AND INTO EARLY
SATURDAY. THE CHANCE OF PRECIPITATION WILL SPREAD EAST OF THE
DIVIDE LATER TONIGHT AND SATURDAY ALTHOUGH AMOUNTS WILL BE LIGHT.
A RIDGE OF HIGH PRESSURE WILL BRING MAINLY DRY WEATHER FROM LATE
SATURDAY THROUGH SUNDAY NIGHT.
&&

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

$$

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