Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 072038
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
238 PM MDT MON JUL 7 2014

.SHORT TERM...TONIGHT THROUGH TUESDAY

COOLER AIR FROM A SERIES OF CANADIAN COLD FRONTS WILL PUSH SOUTH
ACROSS NORTHERN AND CENTRAL AREAS MOVING THROUGH THE SOUTHWEST
TONIGHT AND TUESDAY. ALONG AND NEAR THE HIGHER MOUNTAINS ALONG THE
CONTINENTAL DIVIDE AND OVER THE BIGHORN MOUNTAINS...ISOLATED
SHOWERS AND THUNDERSTORMS ARE EXPECTED THIS EVENING AND AGAIN ON
TUESDAY. OTHERWISE CONDITIONS WILL REMAIN DRY. BRISK NORTHEAST
WINDS WILL BLOW TONIGHT AND TUESDAY.

.LONG TERM...TUESDAY NIGHT THROUGH MONDAY

THE SUBTROPICAL RIDGE WILL WOBBLE AROUND THE FOUR CORNERS/GREAT
BASIN THROUGHOUT THE LONG TERM PERIOD. IT WILL KEEP TEMPERATURES
WARM AND WILL DRAW UP MONSOONAL MOISTURE ALONG THE BACK SIDE OF THE
UPPER HIGH LEADING TO ISOLATED TO SCATTERED THUNDERSTORMS THROUGH
THE PERIOD...OCCASIONALLY ENHANCED BY PASSING SHORT WAVES EJECTED
FROM A PERSISTENT ALASKAN LOW/JET STREAK COMBO...OVER THE TOP OF THE
RIDGE. THERE WILL BE SEVERAL SURGES OF MORE ROBUST MONSOONAL
MOISTURE THAT MAY OR MAY NOT BE FULLY REALIZED BASED ON HOW MUCH
INSTABILITY WE CAN MUSTER.

WEDNESDAY...IT LOOKS LIKE THE FIRST OF THESE SHORT WAVES WILL ARRIVE
WEDNESDAY EVENING WITH MORE WIDELY SCATTERED TO SCATTERED
THUNDERSTORM COVERAGE EXPECTED. THIS FEATURE IS CURRENTLY OVER THE
LAS VEGAS FORECAST AREA AND IT WILL TRAVEL AROUND THE TOP OF THE
RIDGE AND SHOULD ARRIVE IN OUR AREA LATER IN THE DAY. ALONG WITH THE
SHORT WAVE WILL COME THE FIRST DECENT SURGE OF MID LEVEL
MOISTURE...WITH SOME INDICATIONS OF DECENT LOW LEVEL MOISTURE
TRANSPORT FROM THE PLAINS AS WELL...WITH PWAT VALUES APPROACHING ONE
INCH ALONG THE I25 CORRIDOR AND BIGHORN BASIN...WHICH IS ALSO WHERE
THE BETTER CAPE AND SHEAR WILL BE LOCATED SO SOME OF THESE STORMS
COULD BE HEAVY RAIN PRODUCERS.

THURSDAY...THE WAVE EXITS FOR PEAK HEATING ON THURSDAY BUT THERE IS
WEAK INSTABILITY JUST ABOUT EVERYWHERE WITH DECENT LOW AND MID LEVEL
MOISTURE LEFTOVER...ENOUGH FOR AT LEAST SOME ISOLATED THUNDERSTORMS
ON THURSDAY EVEN IF THERE IS NOT MUCH SUPPORT ALOFT.

FRIDAY...NOTHER SHORT WAVE COULD ROTATE THROUGH ON FRIDAY...WITH
SOME MODEL DIFFERENCES IN HOW MUCH MID LEVEL MOISTURE WILL ACCOMPANY
THE WAVE. THERE WILL ALSO BE PLENTY OF INSTABILITY TO WORK WITH AS
MOIST UPSLOPE FLOW FROM THE PLAINS POSSIBLY BACKS INTO AREAS EAST OF
THE DIVIDE...THE GFS IS TRYING TO BRING IN PWAT VALUES AS HIGH AS
1.25 INCHES INTO THE I25 CORRIDOR...THAT COMBINED WITH THE ROBUST
HEATING FROM A WARM AIR MASS AND A CLEAR MORNING...REINFORCED BY THE
SHORT WAVE DYNAMICS AND DECENT WIND SHEAR THERE COULD BE QUITE A BIT
OF THUNDERSTORM ACTIVITY WITH SOME MORE ORGANIZED STORMS POSSIBLE.

SATURDAY THOUGH MONDAY...THUNDERSTORMS ARE POSSIBLE INTO MONDAY AS
THE RIDGE REMAINS JUST TO OUR WEST BUT IT MAY TRY TO WORK NORTH INTO
THE AREA WHICH COULD SQUASH CONVECTION OVER THE SOUTH AND WEST.
THERE ARE SOME INDICATIONS OF A PATTERN CHANGE TOO WITH A DEEP
DIGGING LOW OVER HUDSON BAY...POSSIBLY REINFORCED BY A STRONG SHORT
WAVE COMING OUT OF THE PACNW...THAT COULD SWITCH US TO MORE OF A
NORTHWEST FLOW PATTERN LEADING TO BELOW NORMAL TEMPERATURES AND
CONTINUED DIURNAL CONVECTION IN THE AREAS NORMALLY PRONE TO STORMS
IN NORTHWEST FLOW.

&&

.AVIATION.../00Z ISSUANCE/

A COLD FRONT ALONG THE CONTINENTAL DIVIDE WILL PUSH SOUTH THROUGH THE
WEST OF SOUTHERN WYOMING THIS AFTERNOON AND EVENING.  VFR CONDITIONS
ARE EXPECTED TO PREVAIL AT THE AIRPORTS THROUGH 00Z WEDNESDAY. ALONG
AND NEAR THE CONTINENTAL DIVIDE AND OVER AND NEAR THE NORTHERN
MOUNTAINS ISOLATED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS
ARE EXPECTED TO DEVELOP. AREAS OF NORTHEAST WINDS OF 15 TO 20 KTS
WITH GUSTS AROUND 25 KTS WILL BE ENCOUNTERED NORTH OF THE COLD
FRONT. THROUGH THE EVENING LOCAL MVFR CEILINGS MAY FORM ALONG AND
NEAR THE NORTHERN AND EAST FACING SLOPES AS A LAYER OF
STRATOCUMULUS DEVELOPS ALONG THE FRONTAL BOUNDARY ALOFT ENHANCED
BY UPSLOPE LIFT. AT THIS TIME IT IS UNCERTAIN THAT THE MVFR
CEILINGS WILL IMPACT ANY AIRPORTS DIRECTLY BUT THE BEST CANDIDATES
FOR THIS WILL BE KCOD...KBYG...KCPR...KTHP AND KLND. FEW CLOUDS
ARE EXPECTED TO MAKE IT OVER THE CONTINENTAL DIVIDE WITH MOSTLY
CLEAR CONDITIONS ANTICIPATED IN THE WEST AND SOUTHWEST.

&&

.FIRE WEATHER...

COOLER AIR FROM A SERIES OF CANADIAN COLD FRONTS WILL PUSH SOUTH
ACROSS NORTHERN AND CENTRAL AREAS AND THROUGH THE SOUTHWEST TONIGHT
AND TUESDAY. ALONG AND NEAR THE HIGHER MOUNTAINS ALONG THE
CONTINENTAL DIVIDE AND OVER THE BIGHORN MOUNTAINS...ISOLATED
SHOWERS AND THUNDERSTORMS ARE EXPECTED THIS EVENING AND AGAIN ON
TUESDAY. OTHERWISE CONDITIONS WILL REMAIN DRY. BRISK NORTHEAST
WINDS WILL BLOW TONIGHT AND TUESDAY. HIGH PRESSURE FROM THE GREAT
BASIN WILL BRING A WARM UP WITH MORE WIDESPREAD HIGH BASED
THUNDERSTORMS WEDNESDAY THROUGH FRIDAY.

&&

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

$$

SHORT TERM...C.BAKER
LONG TERM...ALLEN
AVIATION...C.BAKER
FIRE WEATHER...C.BAKER





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