Area Forecast Discussion
Issued by NWS Riverton, WY

Home | 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 292021
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
221 PM MDT MON JUN 29 2015

.SHORT TERM...TONIGHT THROUGH TUESDAY

WV IMAGERY SHOWS LARGE AMPLIFIED BUBBLE HIGH OVR THE WRN
CONUS...CENTERED OVR THE GREAT BASIN...WITH EMBEDDED DISTURBANCES
AND BITS OF MID/UPR MOISTURE CONTINUING TO ROTATE AROUND THE HIGH.
TWO AREAS OF UPSTREAM INCREASED MID/UPR MOISTURE...ONE OVR NV/SWRN
ID...THE OTHER ACROSS SRN BC/ALBERTA...BOTH OF WHICH MAY COME INTO
PLAY TUESDAY. SFC HAS LARGE BROAD AREA OF MODEST HIGH P ACROSS WY
WITH RELATIVELY WEAK LOW P OFF TO THE SW OVR UT AND A DEVELOPING SFC
FRONT ACROSS SRN CANADA.

OVERALL...ISOLATED THUNDER OVR THE HIGHER MOUNTAINS TODAY WITH
LITTLE OR VERY SLOW MOVEMENT AWAY FROM THE GENESIS AREAS. INCREASING
MID LVL MOISTURE THRU THE EARLY MORNING HRS ALONG WITH A SMALL
EMBEDDED UPR DISTURBANCE AND SFC FRONT PUSHING THRU...WILL GIVE
BETTER CHANCES FOR PRECIPITATION ACROSS THE FA TUE.

TODAY/TONIGHT...HOTTEST DAY OF THE WEEK. H5 TEMPS UP ANOTHER DEGREE
OR TWO OVR THOSE OF YESTERDAY. STRONG CAPPING WILL ONLY ALLOW FOR
MAINLY ISOLATED MOUNTAIN THUNDERSTORMS LATER TODAY AND THIS EVENING.
OVERNIGHT AND THRU TUESDAY...MID/UPR LVL MOISTURE WILL BEGIN TO
INCREASE DRAMATICALLY ACROSS THE W AND NRN FA...EVENTUALLY INTO  THE
CNTRL BASINS BY LATE MORNING TUE. SHOWER CHANCES WILL INCREASE
ACROSS THE NW AND NRN CWA OVERNIGHT.

TUESDAY...CLOUDS WILL ALSO BE ON THE INCREASE FROM N TO S THRU THE
DAY. CURRENT HIGH TEMP MAY BE OPTIMISTIC...PARTICULARLY ACROSS THE
NRN HALF OF THE FA. HAVE LOWERED A FEW DEG DUE TO INCREASING CLOUD
COVER BY MID DAY...BUT MAY NOT HAVE BEEN ENOUGH. PWS WILL INCREASE
TO ABOVE 1 INCH OVR THE NRN AND NERN CWA. SFC FRONT SHOULD ENTER THE
NRN FA BY MID DAY...HELPING TO INCREASE AND SPREAD SHOWERS AND
EMBEDDED THUNDER FROM N TO S DURING THE AFTERNOON. FCST SOUNDINGS
SHOW LONG NARROW CAPE AND INCREASING UPR LVL FLOW AND SHEAR THRU MUCH
OF THE AFTERNOON...WITH A FEW STORM CORES ABLE TO PRODUCE HEAVY RAIN
IN SHORT ORDER...AND POSSIBLE LOCALIZED FLASH FLOODING. THIS WILL BE
ESPECIALLY TRUE IN AREAS OF POST FRONTAL TERRAIN FORCED
CONVERGENCE...FROM THE SRN ABSAROKAS AND SRN BIGHORNS...AND THE
REGION IMMEDIATELY ADJACENT TO AND SOUTH OF THE BIGHORN MOUNTAINS.
ADDITIONALLY...A FEW OF THE STRONGER STORMS WILL PRODUCE HEAVY
RAIN...GUSTY (WET) WINDS AND SMALL HAIL MOST LIKELY ACROSS THE
CENTRAL AND NORTHERN BASINS...EWD TO THE FA BORDER. WILL HAVE WATCH
THE SITUATION AS CLOUD COVER...OR THE LACK THEREOF IN PLACES...WILL
AT LEAST PARTIALLY DICTATE STORM INITIATION AND MODE EARLY ON. AN
ISOLATED SEVERE STORM WILL ALSO BE POSSIBLE ACROSS THIS SAME
AREA...BUT MOST LIKELY ACROSS ERN FREMONT THRU NATRONA COUNTY IN THE
EARLY EVENING.

.LONG TERM...TUESDAY NIGHT THROUGH MONDAY

A RETURN OF HIGH PRESSURE WILL HELP TO PUSH SHOWER ACTIVITY OUT OF
SOUTHERN WYOMING TUESDAY EVENING...WITH A STRENGTHENING NORTHWEST
FLOW. A WEAK DISTURBANCE WILL MOVE ALONG THE RIDGE ON
WEDNESDAY...WITH THE BRUNT OF THE SYSTEM IMPACTING NORTHEASTERN
WYOMING. A FEW SHOWERS WILL BE POSSIBLE WITH THIS DISTURBANCE...WITH
ACTIVITY LINGERING ACROSS NORTHEASTERN WYOMING THROUGH EARLY THURSDAY
MORNING. SLIGHTLY COOLER TEMPERATURES...ESPECIALLY ON THURSDAY WHEN
SOME AREAS WILL REACH INTO THE LOW TO MID 80S.

HIGH PRESSURE WILL THEN GENERALLY KEEP MOST SHOWER ACTIVITY LIMITED
THROUGH THE WEEKEND. THIS INCLUDES INDEPENDENCE DAY...WHICH MAY SEE
A FEW SHOWERS OVER THE MOUNTAINS...BUT GENERALLY DRY OVER THE LOWER
ELEVATIONS. WARMING TEMPERATURES ALSO EXPECTED...WITH MOST AREAS
REACHING BACK INTO THE 90S BY SATURDAY.

ANOTHER DISTURBANCE WILL RIDE ALONG THE RIDGE SUNDAY NIGHT AND INTO
MONDAY...GENERATING ADDITIONAL SHOWER AND THUNDERSTORM ACTIVITY.
MODELS VARY A BIT ON THE COVERAGE OF THIS SHOWER ACTIVITY...WITH THE
GFS BEING THE MORE PESSIMISTIC MODEL FOR THOSE ENJOYING THE WARM AND
DRY CONDITIONS. BOTH MODELS DO AGREE HOWEVER... THAT ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE DURING THE
LATER PORTION OF THE FORECAST PERIOD.

&&

.AVIATION.../00Z ISSUANCE/

VFR CONDITIONS WILL PREVAIL AT ALL TERMINAL SITES THROUGH THE
FORECAST PERIOD...WITH A COUPLE OF EXCEPTIONS. ISOLATED EVENING
THUNDERSTORMS WILL CONTINUE OVER THE MOUNTAINS WITH PERHAPS A COUPLE
OF THESE MAKING IT ONTO THE LOWER ELEVATIONS THIS EVENING. THE MAIN
THREAT FROM THESE STORMS WILL BE LIGHTNING AND GUSTY OUTFLOW WINDS
OVER 40 MPH. LATER IN THE  MORNING...MOISTURE WILL BE ON THE
INCREASE AS BOTH A SURFACE FRONT AND A COUPLE OF MID LEVEL
DISTURBANCES BEGIN MOVE THROUGH/NEAR THE FORECAST AREA. SHOWERS AND
ISOLATED THUNDER WILL INCREASE ACROSS THE WEST AND NORTH LATE
OVERNIGHT THROUGH THE MORNING...WITH HIGHER MOUNTAIN OBSCURATIONS
BECOMING MORE LIKELY AS THE MORNING WEARS ON. BE
AFTERNOON...SCATTERED SHOWERS AND EMBEDDED THUNDERSTORMS...A FEW
STRONG...WILL MOVE FROM NORTH TO SOUTH ACROSS WYOMING WITH SOME
TERMINAL SITES SEEING BRIEF MVFR CONDITIONS DUE TO LOWER CIG AND
REDUCED VISIBILITY IN HEAVY RAIN.

&&

.FIRE WEATHER...

FIRE DANGER WILL REMAIN BELOW CRITICAL AS WINDS WILL BE RELATIVELY
LIGHT AND AND FUELS REMAIN IN GREEN-UP. HOWEVER...FIRE DANGER WILL
BE ENHANCED BOTH TODAY AND TOMORROW...PARTICULARLY ACROSS THE
SOUTHERN FORECAST AREA...AS HOT DAY TIME TEMPERATURES CONTINUE WITH
MINIMUM RH VALUES IN THE MID AND UPPER TEENS. WINDS WILL ALSO
OCCASIONALLY GUST GREATER THAN 25 MPH FOR SHORT PERIODS NEAR HIGH
BASED THUNDERSTORMS...MAINLY IN AND ADJACENT TO THE MOUNTAINS
THROUGH THE EARLY EVENING. TUESDAY WILL SEE SOME INCREASE IN
MOISTURE AND HUMIDITY...ESPECIALLY OVER THE NORTHERN FORECAST
AREA...WITH BETTER CHANCES FOR PRECIPITATION IN THE FORM OF SHOWERS
AND EMBEDDED THUNDERSTORMS...AS BOTH AN UPPER LEVEL DISTURBANCE AND
SURFACE FRONT MOVE ACROSS THE REGION.

&&

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

$$

SHORT TERM...BRAUN
LONG TERM...BRANHAM
AVIATION...BRAUN
FIRE WEATHER...BRAUN



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