FXUS65 KRIW 060845
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
245 AM MDT SAT SEP 6 2008

.SHORT TERM...TODAY THROUGH MONDAY NIGHT

SHORTWAVE WILL MOVE ACROSS NORTHERN WY TODAY WITH LIMITED MID LEVEL
MOISTURE. SHOWERS ACROSS NORTHERN WY TODAY WILL BE CONFINED TO
NORTHERN WY AND ARE EXPECTED TO BE ISOLATED IN THE LOWER ELEVATIONS
AND SCATTERED IN THE NORTHERN ABSAROKA AND NORTHERN BIGHORN
MOUNTAINS. SHORTWAVE WILL KEEP COLD POCKET OF AIR ALOFT IN PLACE
ACROSS THE NORTHERN ROCKIES...AND HIGHS TODAY WILL BE 8-12 F BELOW
NORMAL. THE FLOW ALOFT WILL BACK TO THE WEST NORTHWEST BEHIND THE
SHORTWAVE TONIGHT WITH SHOWERS EXITING NORTHEAST WY AND MOVING TO
THE EAST AFTER 06Z WITH ONLY A FEW HIGH ELEVATION SHOWERS IN THE
NORTHERN ABSAROKAS AND NORTHERN BIGHORNS IN WEAK UPSLOPE FLOW AND
DIMINISHING MOISTURE. A DEEPER SHORTWAVE WILL MOVE FROM WESTERN MT
ACROSS NORTHERN AND CENTRAL WY SUNDAY THROUGH SUNDAY NIGHT. THIS
SYSTEM WILL BRING MOISTURE FURTHER SOUTH ACROSS WY WITH RIGHT REAR
H25 JET DYNAMIC SUPPORT SUNDAY AND LEFT FRONT FORCING SUNDAY NIGHT.
SCATTERED TO NUMEROUS SHOWERS AR EXPECTED SUNDAY ACROSS NORTHERN
WY...WHILE ISOLATED SHOWERS AS FAR SOUTH AS THE EAST SLOPES OF THE
WIND RIVER MOUNTAINS AND SOUTHERN NATRONA COUNTY WILL BECOME
SCATTERED BY SUNDAY AFTERNOON. HIGHS SUNDAY WILL BE 2-4 F WARMER
THAN TODAY...AS SLIGHTLY WARMER AIR MOVES NORTHWARD ACROSS WY AHEAD
OF THE APPROACHING TROUGH. GFS AND NAM SOLUTIONS VARY SLIGHTLY
MONDAY WITH THE NAM A LITTLE SLOWER IN LIFTING THE TROUGH TO THE
EAST. KEPT ISOLATED SHOWERS IN THE NORTHERN BIGHORNS WITH THIS
SLOWER SOLUTION IN MIND WITH DRYING ACROSS THE REMAINDER OF THE CWA
GIVEN INCREASING WESTERLY FLOW ALOFT. HIGHS MONDAY WILL BE ONLY A
FEW DEGREES BELOW NORMAL...AS H7 TEMPERATURES WARM 2-5 C.

.LONG TERM...TUESDAY THROUGH SATURDAY

WEST FLOW ALOFT ON TUE WITH WEAK WEATHER DISTURBANCE IN THE FLOW
INDICATED BY BOTH THE GFS AND THE ECMWF MODELS. WILL KEEP THE
ISOLATED SHOWERS IN THE FORECAST FOR THE MTS...THE FAR WEST VALLEYS
AND ACROSS THE SOUTH. A NEW STORM SYSTEM DIVES INTO MONTANA WED WITH
THE TROUGH MOVING INTO WY WED PM AND EVE. PRECIP SHOULD DEVELOP OVER
NORTHERN WY WED PM. THEN THE SYSTEM HAS THE POTENTIAL FOR RAIN AND
MOUNTAIN SNOW WED NIGHT INTO EARLY THURSDAY MORNING ACROSS MUCH OF
THE AREA. STILL PLENTY OF TIME TO SEE HOW DEEP THE TROUGH EVOLVES.
TROUGH EXITS EARLY THURSDAY WITH MORE SUNSHINE IN THE AFTERNOON AS
CLOUDS DECREASE. FRIDAY LOOKS DRY WITH A NW FLOW ALOFT. NEXT
SATURDAY ALSO LOOKS DRY FOR NOW. AS FOR TEMPS...A WARM DAY ON TUE.
COOLER OVER NORTHERN WY WED AS THE FRONT MOVES INTO THAT
AREA...STILL MILD IN THE CENTRAL AND SOUTH. A COOL DAY
THURSDAY...THEN MODERATION NEXT FRI AND SAT.

&&

.AVIATION...

COOL NORTHWEST FLOW WILL CONTINUE OVER NORTHERN AND CENTRAL WYOMING
THROUGH SUNDAY MORNING. THIS WILL BRING AREAS OF LOW CLOUDS AND
SHOWERS TO THE AREA EAST OF THE CONTINENTAL DIVIDE...ESPECIALLY OVER
AND NEAR THE NORTHERN MOUNTAINS. AREAS OF MVFR CONDITIONS WILL BE
ENCOUNTERED WITH LOWERING CEILINGS AND LOCAL LOW VISIBILITY IN THE
HEAVIER PRECIPITATION CELLS...ESPECIALLY OVER AND NEAR THE
MOUNTAINS. THE HIGHER MOUNTAINS WILL BE OBSCURED AT TIMES ACROSS
NORTHERN AND CENTRAL WYOMING. WEST OF THE CONTINENTAL DIVIDE ONLY
ISOLATED SHOWERS ARE EXPECTED ALONG WITH GUSTY NORTHWEST TO WEST
WINDS ACROSS THE SOUTHWEST.

&&

.FIRE WEATHER...

UPPER LEVEL SYSTEM WILL MOVE ACROSS NORTHERN WYOMING TODAY WITH
ISOLATED SHOWERS AND SCATTERED MOUNTAIN SHOWERS EXPECTED. RAINFALL
WILL GENERALLY BE LIGHT WITH A SLIGHT CHANCE OF WETTING RAINS IN THE
NORTHERN ABSAROKA AND THE NORTHERN BIGHORN MOUNTAINS. A TROUGH OF
SURFACE LOW PRESSURE WILL DEVELOP THIS AFTERNOON IN THE WESTERN
PLAINS...AND WEST WINDS ACROSS SOUTHERN WYOMING WILL INCREASE TO 10
TO 20 MPH WITH A FEW GUSTS TO AROUND 25 MPH. A DEEPER UPPER LEVEL
DISTURBANCE WILL MOVE ACROSS NORTHERN AND CENTRAL WYOMING SUNDAY AND
SUNDAY NIGHT...BRINGING SLIGHTLY HIGHER CHANCES OF WETTING RAINS TO
ALL OF THE REGION EXCEPT FOR SOUTHERN WYOMING.

&&

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

&&

$$

SHORT TERM...SMITH
LONG TERM...AR
AVIATION...C.BAKER
FIRE WEATHER...SMITH


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