Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 232011
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
211 PM MDT WED JUL 23 2014

.SHORT TERM...TONIGHT AND THURSDAY

MCS TO OUR EAST LAST NIGHT PUSHED A STRONG...MOIST BOUNDARY WESTWARD
DURING THE EARLY MORNING HOURS RESULTING IN MUCH HIGHER MORNING DEW
POINTS THAN EXPECTED. THE DEW POINTS WERE IN THE UPPER 50S TO NEAR
60 IN JOHNSON AND ERN NATRONA AND LOWER TO MID 50S ALL THE WAY WWD
INTO THE WIND RIVER BASIN. MUCH DRIER SW FLOW IS FINALLY MIXING THE
AREA OUT WITH JOHNSON THE LAST TO GO. CAP IS STRONG SO POTENTIAL LOW
FOR STORMS BUT IF ONE DOES POP IT COULD BE QUITE STRONG BEFORE
MOVING EAST OUR OUR AREA. SWRN MOISTURE PLUME CAME IN QUICKLY AND A
LITTLE FURTHER NWWD THAN THE MODELS INDICATED SO EXPANDED ISOLD DRY
SHOWER/THUNDERSTORM WORDING INTO THE SW AND PARTS OF CENTRAL WYOMING
INTO THE EVENING HOURS. MAIN THREAT WILL BE THE STRONG OUT FLOW
WINDS AND LIGHTNING WITH A FEW CELLS. VERY DRY AIR IN THE SW WITH
RKS DROPPING TO 11 PERCENT BY 11 AM AND 8 PERCENT AT SNOW SPRINGS
CREEK. ANOTHER SURGE OF MID LEVEL SUBTROPICAL MOISTURE IS EXPECTED
OVERNIGHT SO ADDED IN IDEA OF ISOLATED SHOWERS/SLGHT CHC OF
THUNDERSTORMS TO THE SERN ZONES DURING THE LATE NIGHT AND MORNING
HOURS. WEAK RIPPLE IN THE SW FLOW AND JET STREAK MAY ALSO FIRE A FEW
LATE NIGHT STORMS IN THE NWRN MTNS. MORE HIGH BASED STORMS ON
THURSDAY ACROSS THE SERN ZONES AND POSSIBLY ALONG THE FRONT IN
JOHNSON COUNTY. ONE CAVEAT TO THE SERN SWEETWATER COUNTY IS THE
POTENTIAL FOR SOME HIGHER PW AIR TO CLIP THE AREA IN THE AFTERNOON
AS SURGE OF HIGHER THETA AIR CURRENTLY OVER ERN AND CENTRAL AZ
SURGES NWD OVER THE NEXT 24-30 HOURS WITH PW`S OVER AN INCH FORECAST
BY THE GFS TO CLIP SERN SWEETWATER COUNTY. THE NAM IS JUST SLIGHTLY
FURTHER SOUTH DUE TO ITS MORE WLY WIND FLOW IN OUR AREA. THE UPPER
JUST MAY ALSO PROVIDE A LITTLE SUPPORT TOO DOWN THERE.
OTHERWISE...CONTINUED HOT AND WINDY. BREEZY TO LOCALLY WINDY TODAY
BUT STRONGER ON THURSDAY WITH LOW TO THE NORTH AND FRONT PUSHING IN.

.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY

A RELATIVELY QUIET FORECAST PERIOD AS FAR AS CONVECTIVE WEATHER. A
WAVE OF LOW PRESSURE WILL CREATE A PERIOD OF ZONAL FLOW BEGINNING
LATE THURSDAY NIGHT...AND CONTINUING THROUGH FRIDAY. THIS MAY RESULT
IN CONTINUED PERIODS OF GUSTY WIND ACROSS MUCH OF THE FORECAST
AREA...WITH HOT AND DRY CONDITIONS EXPECTED. THIS COMBINATION AND THE
PRESENCE OF CRITICALLY DRY FUELS WILL PERMIT THE CONTINUATION OF THE
RED FLAG WARNING ACROSS THE CENTRAL AND SOUTHERN ZONES.

THE RIDGE OF HIGH PRESSURE WILL BEGIN TO REBUILD OVER THE AREA
SATURDAY AFTERNOON...WITH DRY CONDITIONS EXPECTED. TEMPERATURES WILL
BE SLIGHTLY COOLER ON SATURDAY AND SUNDAY AFTERNOONS IN RESPONSE TO
THE WEAK WAVE. THE RIDGE OF HIGH PRESSURE WILL AMPLIFY OVER THE
FORECAST AREA EARLY NEXT WEEK. HOWEVER...ENOUGH MOISTURE WILL BE
BROUGHT OVER WESTERN WYOMING TO INTRODUCE ADDITIONAL CLOUD
COVER...AND ASSOCIATED SHOWER ACTIVITY. MOST SHOWER ACTIVITY WILL BE
CONFINED TO THE NORTHWEST...WITH A FEW SHOWERS POSSIBLE FURTHER
EAST. THESE SHOWERS AND ADDED MOISTURE WILL CAUSE FLUCTUATIONS IN
TEMPERATURE ACROSS THE AREA THROUGH THE REMAINDER OF THE FORECAST
PERIOD.

&&

.AVIATION.../00Z ISSUANCE/

ISOLATED HIGH BASED SHOWERS AND THUNDERSTORMS WITH OUTFLOW WINDS OF
40 TO 50 MPH WILL BE POSSIBLE THROUGH THE EVENING HOURS IN THE
SOUTHWESTERN AND CENTRAL PARTS OF THE AREA INCLUDING KRKS...KBPI...
KPNA...KLND...KRIW...KCPR AND KWRL. THEY WILL BE FEW AND FAR BETWEEN
FURTHER NORTH BUT THE OUTFLOW WINDS CAN IMPACT THE TERMINALS EVEN
THOUGH THE SHOWER OR STORM IS MANY MILE AWAY. A FEW WEAK SHOWERS ARE
POSSIBLE IN THE SOUTHEAST HALF OF THE AREA DURING THE LATE NIGHT
HOURS WITH ISOLATED GUSTY THUNDERSTORMS RETURNING THURSDAY AFTERNOON
ACROSS THE SOUTH AND EAST INCLUDING KRKS AND KCPR.

&&

.FIRE WEATHER...

A RED FLAG WARNING IS IN EFFECT FOR PORTIONS OF CENTRAL AND SOUTHERN
WYOMING THROUGH FRIDAY EVENING. A FIRE WEATHER WATCH IS IN EFFECT
FOR THE CODY FOOTHILLS FROM NOON ON THURSDAY THROUGH FRIDAY
EVENING. CRITICAL FIRE WEATHER CONDITIONS WILL CONTINUE ACROSS
AREAS WITH CRITICALLY DRY FUELS AS HOT DAYTIME TEMPERATURES IN THE
90S COMBINE WITH LOW RH VALUES RANGING FROM THE UPR SINGLE DIGITS
TO THE MID TEENS AND INCREASING SOUTHWEST TO WEST WINDS.
ADDITIONALLY...THE POSSIBILITY OF ISOLATED THUNDER TODAY ALSO
REINFORCES THIS DECISION. THURSDAY WILL PERHAPS SEE THE MOST
EXTREME BEHAVIOR AS A STRONGLY INCREASED SURFACE PRESSURE GRADIENT
COMBINES WITH STRONGER UPPER LEVEL FLOW TO GIVE WESTERLY WINDS
THAT WILL GUST BETWEEN 25 AND 35 MPH IN THE AFTERNOON AND EARLY
EVENING. SIMILAR CONDITIONS WILL BE PRESENT FRIDAY...ALTHOUGH HIGH
TEMPERATURES WILL BE A BIT COOLER. HAVE ALSO ADDED A FIRE WEATHER
WATCH FOR ZONE 276 (CODY FOOTHILLS) THAT WILL START THURSDAY AT
NOON AND ALSO RUN THRU FRIDAY EVENING FOR SIMILAR REASONING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 9 PM MDT FRIDAY
WYZ279-280-283-285-287-300.

FIRE WEATHER WATCH FROM THURSDAY AFTERNOON THROUGH FRIDAY
EVENING WYZ276.

&&

$$

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





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