Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 090848
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
248 AM MDT WED JUL 9 2014

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT

THE AXIS OF THE RIDGE OF HIGH PRESSURE IS ANTICIPATED TO SLIDE EAST
THROUGH THE FORECAST AREA TODAY. THIS WILL ALLOW A DISTURBANCE IN
THE FLOW TO ALSO MOVE EAST THROUGH THE AREA. THIS DISTURBANCE WILL
BEING ENOUGH MOISTURE AND INSTABILITY TO GENERATE SOME SHOWER AND
THUNDERSTORM ACTIVITY THIS AFTERNOON. ACTIVITY WILL WEAKEN WITH THE
LOSS OF DAYLIGHT...THOUGH SOME ACTIVITY OVER THE CENTRAL MOUNTAINS
MAY LINGER INTO THE OVERNIGHT HOURS.

A NEAR ZONAL FLOW WILL BE IN PLACE ON THURSDAY. ANOTHER DISTURBANCE
IN THE FLOW WILL BRING ANOTHER ROUND OF AFTERNOON SHOWERS AND
THUNDERSTORMS. MODELS INDICATE SOME INCREASED INSTABILITY OVER THE
AREA FOR THURSDAY AFTERNOON AND EVENING. A FEW STORMS COULD BECOME
STRONGER IN THIS ENVIRONMENT. COVERAGE OF SHOWER ACTIVITY IS ALSO
EXPECTED TO INCREASE ACROSS THE AREA COMPARED TO WHAT IS EXPECTED
TODAY.

A SIMILAR SCENARIO IS SET FOR FRIDAY...WITH SHOWERS AND
THUNDERSTORMS DEVELOPING DURING THE AFTERNOON AND EVENING HOURS.
INSTABILITY CONTINUES TO INCREASE ACROSS THE AREA THROUGH FRIDAY
EVENING...WITH ANOTHER OPPORTUNITY FOR STRONGER THUNDERSTORMS ACROSS
THE AREA.

THE EXPECTED CHANGES IN THE WEATHER PATTERN WILL HELP TO COOL
TEMPERATURES DOWN THROUGH THE REMAINDER OF THE WORK WEEK...THOUGH A
SIGNIFICANT COOL IS NOT EXPECTED. WIND IS GENERALLY EXPECTED TO
REMAIN LIGHT THROUGH THE FORECAST PERIOD...WITH JUST A SLIGHT
INCREASE ANTICIPATED DURING THE AFTERNOON HOURS. OF COURSE
THUNDERSTORMS MAY PRODUCE SOME GUSTY WIND.

.LONG TERM...SATURDAY THROUGH WEDNESDAY

THROUGH THE LONG TERM...THE FORECAST AREA WILL BE INFLUENCED BY A
SUBTROPICAL RIDGE GENERALLY FROM THE GREAT BASIN INTO THE SOUTHERN
PLAINS...AND A STRONG HUDSON BAY LOW. THIS SETUP SHOULD RESULT IN A
QUASI-STATIONARY FRONTAL BOUNDARY BEING REINFORCED ON ALMOST A DAILY
BASIS WITH COOLER AIR FROM THE NORTH. AT TIMES THIS BOUNDARY WILL
EVEN SURGE WEST OF THE DIVIDE...ALBEIT ON THE SHALLOW SIDE.
ISOLATED TO SCATTERED CONVECTION IS POSSIBLE EACH DAY...ESPECIALLY
IN THE AFTERNOON AND EVENING. THE STRONGEST COLD PUSH/FRONT IS
EXPECTED TO OCCUR MONDAY INTO MONDAY NIGHT.

TEMPERATURES ARE EXPECTED TO SEASONAL TO SLIGHTLY BELOW AVERAGE
EAST...TO SEASONAL TO ABOVE AVERAGE WEST FOR MUCH OF THE EXTENDED.

&&

.AVIATION.../12Z ISSUANCE/

A COUPLE OF UPPER LEVEL DISTURBANCES WILL ROTATE ACROSS THE NORTHERN
ROCKIES LATE THIS AFTERNOON AND TONIGHT.  ISOLATED TO WIDELY SCT
-SHRA/-TSRA WILL DEVELOP ACROSS THE WEST (VCNTY KJAC-KPNA-KBPI-KRKS)
19Z-22Z AND SPREAD EAST OF THE DIVIDE IN THE LATE AFTERNOON AND
EVENING.  MOST OF THIS ACTIVITY WILL PUSH EAST OF INTERSTATE 25 BY
09Z THURSDAY.  THE MAIN AVIATION HAZARD WILL BE ERRATIC OUTFLOW
WINDS 20-30KTS.

&&

.FIRE WEATHER...

THE RIDGE OF HIGH PRESSURE WILL MOVE EAST OF THE FORECAST AREA THIS
AFTERNOON...ALLOWING A DISTURBANCE WITH MOISTURE AND INSTABILITY TO
MOVE OVER THE AREA. THUNDERSTORMS WILL CONSEQUENTLY BE POSSIBLE.
ZONAL FLOW OVER THE AREA WILL PERMIT ADDITIONAL AFTERNOON SHOWER AND
THUNDERSTORM ACTIVITY ON THURSDAY AND FRIDAY. GUSTY AND ERRATIC WIND
WITH CLOUD TO GROUND LIGHTNING WILL BE THE PRIMARY THREATS WITH
ACTIVITY. THE CHANGING IN SYSTEMS WILL ALLOW TEMPERATURES TO COOL
SLIGHTLY THROUGH THE PERIOD...WITH GENERALLY LIGHT SURFACE WIND
ANTICIPATED.

&&

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

&&

$$

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







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