Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 212138
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
338 PM MDT MON JUL 21 2014

.SHORT TERM...TONIGHT THROUGH TUESDAY
A SERIES OF VORT LOBES TRACKING NORTHEAST ACROSS THE NORTHERN ROCKIES
ARE RESULTING IN SCT CONVECTION ACROSS THE NORTHERN HALF OF THE
CWA WITH CONVECTION BEING AMPED BY A JET COUPLET. WITH 50 TO 60
DEGREE TEMP/DP SPREADS OVER CENTRAL WY...GUSTY ERRATIC SFC WINDS
ARE CERTAINLY A POTENTIAL FROM ANY ONE OF THESE CELLS IN THESE
AREAS. THIS POTENTIAL HAS PROMPTED THE ISSUANCE OF A RED FLAG
WARNING FOR FIRE ZONE 283 THROUGH 02Z THIS EVENING GIVEN THE RH
BELOW 15 PERCENT AND FREQUENT PREVAILING WIND GUSTS ABOVE 25 MPH.
THIS IS IN ADDITION TO THE ON GOING RED FLAG WARNINGS FOR FIRE
ZONES 279 AND 280 UNTIL 02Z THIS EVE. THE FUELS IN ZONE 283 WERE JUST
DEEMED CRITICAL TODAY. A WEAK BACKDOOR COOL FRONT WILL SLIP
SOUTHWEST INTO JOHNSON AND NATRONA COUNTIES AFTER MIDNIGHT
TONIGHT WHICH WILL TEMPORARILY RAISE THE RH IN THOSE AREAS TUESDAY
MORNING BEFORE DRYING OUT DURING THE DAY TUESDAY. A 1022MB SURFACE
HIGH WILL BUILD IN FROM THE WEST TUESDAY...HOWEVER WITH ENOUGH
INSTABILITY ACROSS THE NORTH HALF OF THE STATE AND ENOUGH JET
ENERGY OVERHEAD...WE SHOULD MANAGE TO SQUEAK OUT SOME CONVECTION
OVER THE NORTHERN MTNS TUESDAY AFTERNOON...ESPECIALLY OVER THE BIG
HORN MTNS. HIGH TEMPS WILL BE SIMILAR TUE TO TODAYS HIGHS EXCEPT
PERHAPS A FEW DEGREES COOLER IN JOHNSON COUNTY. WINDS WILL BE
LIGHTER TUESDAY WITH THE INFLUENCE OF THE SFC HIGH.

.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
MAIN WEATHER FOR MY PART OF THE SHORT TERM WILL BE HOT AND DUSTY
WITH BREEZY TO WINDY CONDITIONS. HIGHS WILL BE IN THE 90S TO NEAR
100 EAST OF THE DIVIDE WITH 80S WEST. THE HIGH COUNTRY WILL VARY
FROM THE 60S TO NEAR 80. A FEW THUNDERSTORMS MAY LINGER TUESDAY
EVENING ACROSS THE NWRN AND NRN MTNS...OTHERWISE DRY TUESDAY NIGHT.
WEDNESDAY WILL BE HOT WITH SOME MOUNTAIN WIND SPREADING TO THE LOWER
ELEVATIONS DURING THE AFTERNOON HOURS. POSSIBLE CRITICAL FIRE
WEATHER DAY FROM NEAR KRKS TO CPR. FRONTAL BOUNDARY THAT DROPS DOWN
BEHIND THE SHORTWAVES TO OUR NORTH WILL LEAVE A BOUNDARY ACROSS OUR
ERN ZONES IN THE MORNING THAT WILL LIKELY BE ERODED AS LEE TROUGHING
DEVELOPS AHEAD OF OUR PACNW UPPER LOW. COULD SEE A FEW STORMS FIRE
IN JOHNSON COUNTY BEFORE THE SW WINDS KICK IN DURING THE AFTERNOON.
ALSO A SMALL CHANCE OF SOME MID LEVEL MOISTURE SPREADING FROM THE
RED DESERT UP TOWARDS NATRONA COUNTY AS UPPER HIGH EXPANDS NWD.
CONFIDENCE LOW ON THIS EXCEPT OFF THE UINTAS. LEFT IT IN FOR NOW
WITH JUST ISOLD IN THE FORECAST. A FEW STORMS ARE ALSO POSSIBLE IN
THE NRN MOUNTAINS. ANOTHER HOT DAY THURSDAY AHEAD OF AN APPROACHING
COLD FRONT WITH OUR PACNW/NRN ROCKIES UPPER LOW. NAM HAS THE FRONT
PUSHING INTO THE FAR NORTH A LITTLE FASTER THAN THE GFS SO KEPT THE
ISOLATED POPS IN THE NRN ZONES TO ACCOUNT FOR THIS. ONLY OTHER AREA
IS OFF THE UINTAS IN A MORE WLY FLOW. OTHERWISE...HOT AND BREEZY TO
WINDY. PROBABLY A LITTLE MORE WIND THAN WEDNESDAY WITH ANOTHER
CRITICAL FIRE WEATHER DAY POSSIBLE FOR OUR CRITICAL FUEL AREAS.
MAYBE A CHANCE EVEN FOR THE WIND RIVER BASIN. CERTAINLY HOT WITH LOW
RH`S AND A BREEZE.

SIDING WITH THE GFS/GEM SOLUTION FOR THE MEDIUM RANGE
PERIOD...FRIDAY THROUGH MONDAY...WITH UPPER LOW PASSING OFF TO THE
NORTH AND EAST AND RIDGE REBUILDING TO OUR WEST WITH NW FLOW OVER
THE AREA THROUGH THE WEEKEND. LOOKS DRY THROUGH THE WEEKEND BUT NOT
AS HOT AS THE SHORT TERM PERIOD WITH EXPECTED NW FLOW AND HIGHER
SURFACE PRESSURES TO THE NE. COULD SEE MONSOONAL MOISTURE START TO
EDGE INTO THE AREA BY MONDAY SO LEFT IDEA OF ISOLATED THUNDERSTORMS
FOR THE HIGHER TERRAIN.

&&

.AVIATION.../00Z ISSUANCE/
WITH DAYTIME HEATING ISOLATED TO SCATTERED CONVECTION /SHRA AND
TSRA/ WILL CONTINUE TO DEVELOP FOR THE REST OF THIS AFTERNOON
AND LAST THROUGH THE EARLY EVENING...MAINLY ALONG AND NORTH OF A
KAFO-KBPI-KBVR-ALCOVA LINE. VFR CONDITIONS ARE EXPECTED...EXCEPT
BRIEF IFR/MVFR CONDITIONS ASSOCIATED WITH ANY CONVECTION. BREEZY
WEST TO SOUTHWEST WINDS WILL BE OBSERVED IN MOST LOCATIONS THIS
AFTERNOON. 50 MPH WINDS ARE POSSIBLE NEAR ANY THUNDERSTORMS. MUCH
OF THE CONVECTION WILL WANE BY AROUND 03Z TUESDAY...BUT ISOLATED
CONVECTION COULD CONTINUE WELL INTO THE NIGHT...MAINLY OVER THE
NORTHWEST. LESSER THUNDERSTORM ACTIVITY IS EXPECTED TUESDAY AFTERNOON
AND WILL BE CONFINED MAINLY TO THE NORTHERN MTNS.

&&

.FIRE WEATHER...
THE COMBINATION OF WARM TEMPERATURES...GUSTY WINDS AND RELATIVE
HUMIDITY IN THE LOW TEENS WITH BRING CRITICAL FIRE WEATHER TO SWEETWATER
COUNTY...LOWER ELEVATIONS OF NATRONA COUNTY...THE WIND RIVER BASIN AND
THE LANDER FOOTHILLS AGAIN FOR THE REST OF THIS AFTERNOON AND
EVENING. MOISTURE MOVING NORTH WILL BRING SOME SHOWERS AND
THUNDERSTORMS...SOME WETTING...TO THE NORTH HALF OF WYOMING. ELSEWHERE
...EXPECT ELEVATED FIRE DANGER FOR THE REST OF THIS AFTERNOON WITH
GUSTY WINDS. FIRE CONDITIONS SHOULD IMPROVE ON TUESDAY AS WINDS
WILL SUBSIDE. VERY WARM TEMPERATURES AND A GUSTY BREEZE DEVELOPING
MAY BRING MORE ELEVATED FIRE DANGER FOR WEDNESDAY AS RIDGING
STRENGTHENS ACROSS THE AREA.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING WYZ279-280-283.

&&

$$

SHORT TERM...LIPSON
LONG TERM...SKRBAC
AVIATION...LIPSON
FIRE WEATHER...LIPSON




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