Area Forecast Discussion
Issued by NWS Riverton, WY

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS65 KRIW 220650
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1150 PM MST FRI NOV 21 2014

.SHORT TERM...TONIGHT THROUGH SATURDAY (ISSUED AT 242 MST)

AN INTERESTING PERIOD. RELATIVELY BENIGN CONDITIONS EXPECTED
DURING THE EARLY EVENING HOURS TONIGHT...WITH A SIGNIFICANT WINTER
SYSTEM EXPECTED TO IMPACT THE AREA DURING THE OVERNIGHT HOURS.
SNOWFALL WILL BEGIN BEFORE MIDNIGHT...WITH ACTIVITY AND COVERAGE
INCREASING THROUGH THE OVERNIGHT HOURS. SNOWFALL RATES WILL
INCREASE DURING THE MORNING HOURS...ESPECIALLY BETWEEN 0500 AND
1100 SATURDAY. SNOWFALL ASSOCIATED WITH THIS SYSTEM WILL CONTINUE
IMPACT THE AREA THROUGH SATURDAY...WITH ACTIVITY SPREADING TO
INCLUDE PORTIONS OF SOUTHERN WYOMING DURING SATURDAY AFTERNOON.

SNOWFALL ACCUMULATIONS WILL BE SIGNIFICANT ACROSS THE WESTERN
MOUNTAINS AND VALLEYS...WITH SOME LESSER AMOUNTS EXPECTED ACROSS
SOUTHERN WYOMING. STORM STORM WILL CONTINUE INTO SATURDAY
NIGHT...WITH FURTHER DETAILS ON TOTAL ACCUMULATIONS COVERED IN THE
LONG TERM SECTION.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
THE SHORTWAVE EJECTED BY THE LOW SPINNING AROUND IN THE ALEUTIANS
WILL BE CROSSING OVER OUR AREA AROUND 06Z SATURDAY NIGHT. AFTER THE
FROPA...THE SNOWFALL INTENSITY WILL BEGIN TO DIMINISH IN THE WEST.
HOWEVER...MANY AREAS OF SWEETWATER COUNTY SHOULD SEE 2 TO 3 INCHES
OF SNOWFALL SATURDAY NIGHT FROM THE COMBINATION OF THE ASCT STRONG
PACIFIC COLD FRONT AND Q VECTOR FORCING. THE WIND RIVER BASIN ALMOST
ALWAYS MANAGES TO RECEIVE AT LEAST JUST UNDER AN INCH OF SNOWFALL
WHENEVER CENTRAL WYOMING RECEIVES THE BRUNT OF THE 700MB COLD PUNCH
FROM A CLASSIC CATAFRONT LIKE THIS ONE AS WILL BE THE CASE SATURDAY
NIGHT...SO INCREASED POPS THERE AS WELL AS ADDED CORRESPONDING SNOW
ACCUMULATIONS THERE. JOHNSON COUNTY IS ANOTHER AREA TO WATCH FOR
MORE PRECIP SINCE THAT AREA WILL BE CLOSER TO THE 700MB LOW TRACKING
EAST SOUTHEAST ACROSS NORTH DAKOTA BUT THE PRECIP THERE WILL START
AS RAIN SO NOT EXPECTING TOO MUCH IN THE WAY OF ACCUMULATING SNOW
THERE. SNOW TOTALS OF 3 TO 5 INCHES WILL BE COMMON IN THE BIG HORN
MTNS.

AS FAR AS SNOW TOTALS GO IN THE FAR WEST...BY 12Z SUNDAY MORNING WE
WILL BE LOOKING AT 12 TO 20 INCHES IN THE TETONS...GROS VENTRE
RANGE...SALT AND WYOMING RANGES AND ALONG AND WEST OF THE DIVIDE IN
THE WIND RIVER MTNS ALONG WITH LOCAL AMOUNTS OF UP TO 26 INCHES. THE
JACKSON VALLEY CAN EXPECT 8 TO 12 INCHES WITH THE HIGHEST AMOUNTS
EXPECTED IN THE NORTH. THE STAR VALLEY WILL SEE 6 TO 8 INCHES.
SOUTHERN LINCOLN COUNTY WILL SEE 2 TO 4 INCHES AROUND OPAL AND 4 TO
8 INCHES AROUND COKEVILLE. YELLOWSTONE PARK WILL HAVE SNOW TOTALS
RANGING FROM 16 INCHES IN THE SOUTHWEST TO 3 TO 8 INCHES IN THE
NORTH INCLUDING MAMMOTH. THE ABSAROKAS WILL SEE UP TO A FOOT IN THE
WEST TO MAINLY 3 TO 10 INCHES IN THE EAST. AREAS JUST WEST OF DUBOIS
WILL SEE 4 TO 8 INCHES WITH 1 TO 3 INCHES JUST TO THE EAST. THE
UPPER GREEN RIVER FOOTHILLS WILL SEE AROUND 9 INCHES AT BONDURANT TO
5 INCHES IN PINEDALE. THE UPPER GREEN RIVER BASIN WILL SEE 3 TO 6
INCHES.

POST FRONTAL 7 TO 8MB...3 HOURLY SFC PRESSURE RISES WILL KEEP
POST FRONTAL NW WINDS UP THROUGH MID DAY SATURDAY IN THE 30 TO 40
MPH RANGE WITH GUSTS TO 50 MPH IN THE WIND RIVER BASIN AND NORTHERN
JOHNSON COUNTY. HIGH TEMPERATURES SUNDAY SHOULD BE 10 TO 15 DEGREES
COLDER SUNDAY THAN ON SATURDAY MOST AREAS. OCCASIONAL SNOWFALL WILL
CONTINUE THROUGH SUNDAY AND INTO MONDAY IN THE FAR WEST AS A SERIES
OF VORT LOBES PARADES WITHIN THE NORTHWEST FLOW WITH ONE DISTINCT
SHORTWAVE COMING THROUGH MONDAY. ON TUESDAY THE JET STREAM WILL PASS
OVERHEAD AS IT SLIDES OFF TO THE NORTHEAST OF US WHICH WILL PULL IN
MORE MOISTURE FROM THE NORTHWEST CONTINUING THE LIGHT TO
OCCASIONALLY MODERATE SNOW IN THE NORTHWEST MTNS. EXCEPT FOR SOME
CONTINUING LIGHT SNOW IN THE BIG HORN MTNS...AREAS EAST OF THE
DIVIDE WILL DRY OUT AFTER SATURDAY NIGHT. FOR THE REST OF THE
WEEK... TUESDAY NIGHT THROUGH THU...THE GFS AND THE EURO HAVE COME
MORE IN LINE WITH A HIGH PRESSURE RIDGE BUILDING IN FROM THE WEST
WITH A GRADUAL WARMING TREND. HOWEVER...WITH THE RIDGE AXIS STILL TO
THE WEST AND CONTINUING NW FLOW...WILL KEEP LOW POPS IN THE NORTHERN
AND CENTRAL MTNS FOR THIS TIME FRAME. WOULD RATHER WAIT FOR MORE RUN
TO RUN MODEL CONSISTENCY BEFORE WE WOULD BE WILLING TO TONE DOWN THE
MTN POPS ANY MORE THAN THEY ALREADY ARE...ESPECIALLY SINCE THIS IS A
SENSITIVE TIME OF THE MONTH GIVEN ALL THE HOLIDAY TRAVELERS.

&&

.AVIATION.../06Z ISSUANCE/
EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES AREAS OF LLWS
WILL QUICKLY DEVELOP TONIGHT OVER THE CENTRAL BASINS AS WEST WINDS
FL075-100 INCREASE TO BETWEEN 35-50KTS 06Z-12Z SATURDAY.  THESE
STRONGER WINDS WILL MIX DOWN TO THE SURFACE FROM VCNTY 50NE SM
KRKS-KCPR AND FROM VCNTY KCOD-KDUB WHERE HIGH WIND WARNINGS ARE IN
EFFECT.  A STRONG COLD FRONT WILL PUSH ACROSS THE AREA EARLY
SATURDAY EVENING.  MTNS WILL BE MOSTLY OBSCURED ALONG THE DIVIDE
AHEAD OF THE FRONT WITH SOME BLOW OVER PCPN IN THE VCNTY OF
KLND-KCOD DURING THE AFTERNOON.  A BAND OF SNOW WILL LIKELY
ACCOMPANY THE FRONT SATURDAY EVENING ALONG WITH AREAS OF MVFR/IFR
-SN MAINLY VCNTY ALONG AND EAST OF THE BIGHORN RANGE AND INTERSTATE
25.  AREAS OF SFC NW WINDS AT 20-30KTS WITH GUSTS TO 40KTS WILL
FOLLOW THE FRONT...DECREASING AFTER 06Z SUNDAY.


WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES
SNOW AND MVFR/IFR CONDITIONS WILL INCREASE VCNTY AND NORTH OF A
KEMM-KPNA LINE 09Z-14Z WITH THESE CONDITIONS BECOMING WIDESPREAD
AFTER 14Z. LLWS WILL ALSO INCREASE ACROSS THE AREA EARLY THIS
MORNING AS FL075-100 WINDS INCREASE TO BTWN 35-50KTS.  A STRONG COLD
FRONT WILL PUSH ACROSS THE AREA SATURDAY AFTERNOON BRINGING
WIDESPREAD IFR...AREAS OF LIFR CONDITIONS IN SN/BLSN ALONG...AREAS
OF WEST SFC WIND 20-30KTS WITH GUSTS TO 40KTS.  SNOW AND WIND WILL
DECREASE AFTER 02Z SUNDAY BEHIND THE FRONT WITH NMRS SHSN LINGERING
OVER THE MOUNTAINS AND MAINLY SCT SHSN OVER THE VALLEYS WITH SOME
MORE ORGANIZED BANDING POSSIBLE...ESPECIALLY VCNTY KJAC-KAFO.

&&

.FIRE WEATHER...

A SIGNIFICANT WINTER WEATHER SYSTEM WILL BEGIN IMPACTING WESTERN
WYOMING THIS EVENING...AND SNOWFALL SPREADING TO INCLUDE MUCH OF
THE FORECAST AREA BY SATURDAY AFTERNOON. WINTER WEATHER HIGHLIGHTS
AREA IN EFFECT. ADDITIONALLY...STRONG WIND WILL DEVELOP ACROSS THE
WIND CORRIDOR BETWEEN ROCK SPRINGS AND CASPER...AND WILL ALSO
DEVELOP IN THE CODY FOOTHILLS. HIGH WIND WARNINGS ARE IN EFFECT
FOR MUCH OF THE DAY SATURDAY FOR THESE LOCATIONS. FIRE WEATHER
BEHAVIOR IS EXPECTED TO REMAIN MINIMAL UNDER THIS SYSTEM...WITH
THE BEST DISPERSION RATES OCCURRING DURING THE STORM. PLEASE SEE
THE APPROPRIATE WEATHER HIGHLIGHT PRODUCT FOR ADDITIONAL
INFORMATION REGARDING THE WINTER STORM AND HIGH WIND
WARNINGS...AND THE WINTER WEATHER ADVISORY.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING FROM 6 AM SATURDAY TO MIDNIGHT MST SATURDAY
NIGHT WYZ003-019-020-022.

WINTER WEATHER ADVISORY FROM 3 AM SATURDAY TO 6 AM MST SUNDAY
WYZ016-026-027.

WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM MST SUNDAY
WYZ001-002-012>015-023>025.

&&

$$

SHORT TERM...BRANHAM
LONG TERM...LIPSON
AVIATION...AEM
FIRE WEATHER...BRANHAM










USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.