Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 250458
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1058 PM MDT TUE MAR 24 2015

.UPDATE...WILL KEEP HIGHLIGHTS GOING AS IS THROUGH THE NIGHT. STILL
EXPECTING SOME SNOW EAST OF THE DIVIDE OVERNIGHT INTO WED MORNING.
CONDITIONS IMPROVING OVER THE WEST BY 12Z AS SNOW SHOWERS DECREASE.

.SHORT TERM...TONIGHT THROUGH WEDNESDAY (ISSUED AT 213 PM MDT)

ACTIVE WEATHER CONTINUES THROUGH MUCH OF THIS PERIOD AS NEXT POTENT
SYSTEM MOVES QUICKLY SE ACROSS THE AREA TONIGHT. SNOW GOT STARTED
QUICKLY THIS MORNING IN THE FAR WEST AS EXPECTED. ADVISORY FOR THE
FAR WEST MOUNTAINS IS LOOKING GOOD WITH A GENERAL 4 TO 8 INCH AMOUNT
FOR MOST OF THE HIGH COUNTRY AND 1 TO 3 INCHES IN THE VALLEYS/LOWER
ELEVATIONS. SHORTWAVE/VORT/JET STREAK SUPPORT MAX BLASTS EAST OF THE
DIVIDE THIS EVENING WITH CONSIDERABLE SNOW AND BLOWING SNOW IN THE
HIGH COUNTRY AND LOTS OF WIND AND AREAS OF SNOW SHOWERS EAST OF
THE DIVIDE...POSSIBLE MIXED WITH RAIN AT FIRST. FEW OF THE WINDIER
SPOTS MAY BE CLOSE TO OR AT HIGH WIND FOR A SHORT TIME WITH FROPA.
WINDS BEND MORE NORTH TONIGHT AS COLD FRONT THEN DROPS DOWN FROM THE
NORTH WITH NICE NW-N CONVERGENCE BOUNDARY AND CYCLONIC SIDE OF THE
JET PUSHES A BAND OF SNOW SWD. LOOKS LIKE A QUICK SHOT OF A SKIFF
TO 2 INCHES UP NORTH WITH A MORE CONCENTRATED BAND WITH SOME
UPSLOPE AROUND CASPER WWD INTO ERN FREMONT. EXPECT 2-3 INCHES IN
THE LOWER ELEVATIONS OF NATRONA COUNTY WITH LOCAL 4 WHERE HEAVIER
SNOW SHOWERS PERSIST OR NEAR CASPER MOUNTAIN. 6-9 ON CPR MOUNTAIN.
RIW AND LND ARE ON THE EDGES OF THIS CONVERGENCE AXIS BUT STILL
EXPECT A BAND OF SNOW TO EITHER SAG SWD WITH THE FRONT OR A POTENTIAL
BAND OF SNOW OR TWO TO MOVE SEWD ACROSS THE WIND RIVER BASIN. COULD
ALSO SEE A BRIEF UPSLOPE TOWARDS 12Z TO GIVE LND A COUPLE HOURS OF
SNOW. CONDS IMPROVE QUICKLY IN THE MORNING WITH ENOUGH INSTABILITY
AROUND THROUGH THE MORNING TO KEEP SOME SNOW SHOWERS OVER AND NEAR
THE MOUNTAINS BEFORE DECREASING AS SOME MID LEVEL WARMING STABILIZES
THE ATMOSPHERE A LITTLE IN THE AFTERNOON.

.LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY

WEDNESDAY NIGHT THROUGH TUESDAY

BEGINNING OF FCST...RIDGE ACROSS THE WRN CONUS...WITH SW TROF THRU
AND RELATIVELY COLD NW FLOW ALOFT...WHILE THE AREA IS POST FRONTAL
AT THE SFC. UNSTABLE BUT DECREASING SHOWERY CONDITIONS PREVAILING
EARLY...MAINLY E OF THE DIVIDE. THEN BY SUN-UP THU MORNING...THE
NEXT UPR LVL DISTURBANCE FLIES SWD...SKIMMING ERN WY AND DRAGGING A
SECONDARY CLIPPERISH FRONT THRU THE FA...AGAIN E OF THE DIVIDE.
AVAILABLE MOISTURE WILL BE ON THE DECREASE AS THE WRN RIDGE BEGINS
TO TRANSLATE EWD AS THIS SMALL SYSTEM MOVES THRU...SHUNTING BETTER
MOISTURE OFF TO THE E. STILL...CHC OR BETTER POPS NRN
MOUNTAINS...SLIGHT TO CHC E OF THE DIVIDE AT LOWER ELEVATIONS WITH
ALL POPS DECREASING QUICKLY BY THU NIGHT.

RIDGING AND WARMING TREND THRU SAT BEFORE NEXT SYSTEM HEADS INTO
THE REGION OVERNIGHT. THIS ALSO COINCIDES WITH A BREAKDOWN IN WHAT
WAS FAIRLY GOOD SPATIAL CORRELATION BETWEEN THE LR MDLS TO THAT
POINT. REALLY COMES DOWN TO WHAT TO DO WITH AN INCOMING AND FAIRLY
VIGOROUS EPAC TROF AS IT PLOWS INTO THE RIDGE FROM THE WEST. AS IT
FALLS APART...WHERE WILL THE DEEPEST PART OF THE UPR LOW SET-UP.
OTHERWISE...AS THE TREND IS TO KEEP UPR LVL NW FLOW AROUND THE
REGION EXCEPT FOR A COUPLE OF SHORT INTERMITTENT BLIPS...AND SINCE
TIMING DOES NOT SEEM TO BE THAT MUCH OF AN ISSUE...HAVE STAYED WITH
THE IDEA OF KEEPING THE FA...QUOTE... UNSETTLED...UNQUOTE THRU THE
END OF THE FCST PERIOD...WHEN PERHAPS THE BEST CHANCE FOR NEW
PRECIP/SNOW ACROSS THE AREA COMES TOGETHER MORE
COHESIVELY.

&&

.AVIATION.../06Z ISSUANCE/

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

A COLD FRONT CONTINUES TO MOVE SOUTH AND SNOW SHOWERS WILL DEVELOP
BEHIND IT AND IMPACT MANY AREAS. IN THE NORTH...THE MVFR/IFR
CONDITIONS WILL OCCUR FROM 06Z UNTIL 12Z. THEN IN THE CENTRAL AREAS
INCLUDING KCPR...KRIW AND EVENTUALLY KLND...SNOW SHOWERS WITH
MVFR/IFR CONDITIONS WILL OCCUR FROM 09Z UNTIL 16Z. CONDITIONS WILL
IMPROVE FROM NORTH TO SOUTH IN THE MORNING WITH SNOW SHOWERS
RETREATING TO MAINLY THE HIGH COUNTRY BY MID MORNING WEDNESDAY
THROUGH WEDNESDAY AFTERNOON. EXPECT VFR CONDITIONS TO PREVAIL AT THE
TERMINAL SITES AFTER 18Z WED THROUGH 06Z THURS.

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

SNOW SHOWERS WILL BE ON THE DECREASE OVERNIGHT WITH MAINLY MOUNTAIN
SNOW SHOWERS AFTER 12Z THROUGH 00Z. LOCAL MVFR/IFR CONDITIONS WILL
OCCUR UNTIL 11Z THEN THE MVFR/IFR CONDITIONS WILL BE CONFINED TO THE
MOUNTAINS WHERE THE SNOW SHOWERS WILL LINGER. TERMINAL SITES WILL
SEE VFR CONDITIONS PREVAILING FROM 12Z WED THROUGH 06Z THURS.

&&

.FIRE WEATHER...

A NEW WEATHER SYSTEM WILL BRING CONSIDERABLE WIND AND SNOW SHOWERS
TO MUCH OF THE AREA INTO TONIGHT AND EAST OF THE DIVIDE INTO
WEDNESDAY MORNING. MANY AREAS WILL SEE WEST TO NORTHWEST WIND OF 20
TO 30 MPH WITH GUSTS OF 40 TO 50 MPH INTO THIS EVENING. WINDS WILL
NOT BE AS STRONG ON WEDNESDAY BUT GUSTY WEST TO NORTHWEST WIND IS
STILL EXPECTED IN THE SOUTH. IT WILL BE COOL ON WEDNESDAY WITH HIGHS
IN THE 30S AND 40S WITH MIN RH`S GENERALLY IN THE 30S AND 40S EXCEPT
BRIEFLY IN THE 20S IN THE SOUTHWEST.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 3 AM TO 9 AM MDT WEDNESDAY
WYZ020-022.

WINTER WEATHER ADVISORY UNTIL 3 AM MDT WEDNESDAY
WYZ001-002-012-024.

WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 9 AM MDT
WEDNESDAY WYZ008-009.

&&

$$

UPDATE...AR
SHORT TERM...SKRBAC
LONG TERM...BRAUN
AVIATION...SKRBAC/AR
FIRE WEATHER...SKRBAC





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