Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 190508
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1110 PM MDT SAT OCT 18 2014


UPDATE...UPDATED TO ADD 06Z AVIATION DISCUSSION.

.SHORT TERM...TONIGHT THROUGH SUNDAY (ISSUED AT 241 PM MDT)

UPR LVL PATTERN SHOWING RELATIVELY FLAT RIDGING...WITH A WEAK UPR
WAVE DOING THE FLATTENING WHILE MOVING THRU THE RIDGE OVR WYO THIS
AFTERNOON WITH A COUPLE OF ISOLATED CONVECTIVE ELEMENTS SHOWING UP
IN PARK COUNTY. THE SFC SHOWS HIGH PRESSURE IN PLACE ACROSS THE WRN
FA...WITH A WEAK TROF MOVING EWD WITH THE UPR WAVE. SFC WINDS REMAIN
LOW UNDER THESE CONDITIONS WITHOUT MUCH SFC GRAD OR SUPPORT FROM
ABOVE...REMAINING SO THRU THE REST OF THE FCST PERIOD. THE CURRENT
UPR WAVE IS ONLY GENERATING SOME MID/UPR CLOUDINESS AND THAT`S ABOUT
IT. OTHERWISE...H7 WARMING WILL ALLOW TEMPS AT THE SFC TO RISE SOME
5+ DEG OVER THOSE OF FRIDAY...WITH SIMILAR HIGHS ON SUNDAY AS DRY
AND STABLE CONDITIONS CONTINUE.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY

LONG WAVE LOW PRESSURE TROUGHS OFF THE WEST COAST AND OVER THE
EASTERN U.S. WILL REMAIN IN PLACE THROUGH THE EXTENDED FORECAST.
THIS PLACES A LARGE HIGH PRESSURE RIDGE OVER THE GREAT PLAINS.
WESTERN AND CENTRAL WYOMING ENDS UP WITH WEST TO SOUTHWEST FLOW
ALOFT.  MODELS INDICATE SHORT WAVE LOW PRESSURE TROUGHS SKIRT TO
THE NORTH OF WYOMING OVER THE NORTHERN ROCKIES ACROSS MONTANA AND
SOUTHERN CANADA AND TO THE SOUTH ACROSS CENTRAL AND SOUTHERN GREAT
BASIN.  SUNDAY NIGHT THROUGH MONDAY NIGHT LOOKS DRY AND RELATIVELY
MILD.  ONE OF THE NORTHERN SHORT WAVE TROUGHS LOOKS TO BE STRONG
ENOUGH TO BRING SOME SHOWERS TO THE WESTERN AND NORTHERN MOUNTAINS
AND COOLS TEMPERATURES FOR TUESDAY NIGHT AND WEDNESDAY. THEN
FORECAST DRIES OUT AGAIN WITH WARMING THROUGH SATURDAY.  MAIN SPREAD
IN THE EXTENDED MODELS OCCURS ACROSS THE NORTHERN ROCKIES...MONTANA
AND SOUTHERN CANADA IN TRACK OF SHORT WAVE TROUGHS WHERE DIFFERENCES
IN TIMING OF SHORT WAVE TROUGHS INCREASES UNCERTAINTY.

&&

.AVIATION.../06Z ISSUANCE/

CONDITIONS WILL BE VFR WITH WINDS LESS THAN 10KTS AT ALL TERMINALS
THROUGH THE PERIOD. DRIER AIR IN NORTHWEST ALOFT WILL KEEP MID/HIGH
LEVEL CLOUDS TO THE SOUTH OF THE FORECAST AREA.

&&

.FIRE WEATHER...

FIRE DANGER IS LOW...AND WILL REMAIN RELATIVELY LOW THROUGH MONDAY
ACROSS THE ENTIRE FORECAST AREA AS SEASONABLY WARM TEMPERATURES AND
LOW WIND SPEEDS CONTINUE FOR ANOTHER COUPLE OF DAYS. WHILE RELATIVE
HUMIDITY VALUES MAY DIP INTO THE LOWER 20S OR EVEN UPPER TEENS AT
TIMES...WINDS SPEEDS WILL REMAIN ON THE LOW SIDE...HELPING TO AVOID
ENHANCED FIRE DANGER.

&&

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

$$

SHORT TERM...BRAUN
LONG TERM...C.BAKER
AVIATION...CNJ
FIRE WEATHER...BRAUN







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