Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 080841
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
241 AM MDT TUE JUL 8 2014

.SHORT TERM...TUESDAY THROUGH THURSDAY NIGHT

IT IS ANOTHER FAIRLY QUIET NIGHT TONIGHT IN THE HUMBLE WEATHER ABODE
IN BEAUTIFUL RIVERTON WYOMING. RIDGING WILL CONTINUE TO CONTROL THE
WEATHER TODAY SO MOST AREAS SHOULD HAVE A CARBON COPY OF YESTERDAYS
WEATHER TODAY ALTHOUGH WITH ONE EXCEPTION. WITH LESS OF A PRESSURE
GRADIENT THE AREAS THAT SAW THE GUSTY BREEZE YESTERDAY WILL SEE LESS
OF THAT TODAY. TEMPERATURES SHOULD REMAIN FAIRLY COMFORTABLE ACROSS
THE AREA AS WELL. AS FOR THE CHANCE FOR CONVECTION...THE MODELS
CONTINUE TO BE RATHER MEAGER WITH THE PRINT OUT. AS A RESULT...WE
REMOVED POPS FROM MOST OF THE LOWER ELEVATIONS WITH ONLY ISOLATED
POPS OVER THE MOUNTAINS. BUT EVEN HERE...COVERAGE SHOULD ONLY BE
ISOLATED WITH THE VAST MAJORITY OF TIME BEING RAIN FREE.

THE PATTERN WILL BEGIN TO CHANGE AS WE HEAD INTO WEDNESDAY HOWEVER.
FLOW LOOKS TO TURN MORE WESTERLY  AND THIS WILL ALSO ALLOW
TEMPERATURES TO WARM BACK TOWARD SOMEWHAT ABOVE NORMAL LEVELS...BUT
NOT AS HOT AS WE SAW LAST WEEKEND. A BIT OF A SHORTWAVE IS ALSO
MOVING TOWARD THE AREA THAT WILL PROVIDE A BIT MORE INSTABILITY.
THE NEXT QUESTION IS THE POSSIBLE ARRIVAL OF SOME MONSOONAL
MOISTURE. THE MODELS CONTINUE TO HAVE DIFFERENCES WITH THE NAM
HAVING MORE QPF AND HIGHER PWATS...APPROACHING AN INCH IN EASTERN
AREAS AS WELL AS PORTIONS OF THE BIG HORN BASIN. THE GFS ON THE
OTHER HAND IS DRIER. AT THE POINT...CONTINUITY HAD ISOLATED
AFTERNOON AND EVENING CONVECTION AND THIS STILL LOOKS LIKE A
REASONABLE COMPROMISE GIVEN THE MODELS DIFFERENCES. WITH THE
UNCERTAINTY...WE DID NOT FEEL COMFORTABLE ENOUGH YET TO INTRODUCE
ANY MODIFIERS TO ANY THUNDERSTORM ACTIVITY. THERE COULD BE SOME
GUSTY WINDS BUT THIS PRETTY MUCH DESCRIBES ANY THUNDERSTORM IN
WYOMING.

AT THIS POINT THURSDAY ALSO LOOKS LIKE A CHANCE FOR CONVECTION IN
THE AFTERNOON. THE GFS SHOWS THIS DAY AS THE MORE LIKELY DAY FOR
CONVECTION WITH HIGHER PRECIPITABLE WATER VALUES. THEY ARE ALSO
STILL DECENT ON THE NAM. ONCE AGAIN...CONTINUITY POPS LOOKED
REASONABLE SO WE MADE FEW CHANGES.

.LONG TERM...FRIDAY THROUGH TUESDAY

INTERESTING PATTERN SETTING UP FOR THE MEDIUM RANGE PERIOD AND
LIKELY QUITE ACTIVE. UPPER HIGH STARTS OFF TO OUR SE IN THE OK
REGION BEFORE GRADUALLY BUILDING NWWD AND END UP SOMEWHERE BETWEEN
THE 4-CORNERS AREA OR SRN GREAT BASIN. DETAILS...SOME NOT SO
MINOR...DO KEEP CHANGING WITH EACH MODEL RUN BUT BIGGER PICTURE
STILL LOOKS TO SUPPORT SOME ACTIVE THUNDERSTORM DAYS. NOT EVERY DAY
AND TOUGH TO PICK THE ABSOLUTE BEST DAY OR TWO BUT THERE WILL LIKELY
BE AT LEAST A COUPLE ACTIVE THUNDERSTORM DAYS. FRIDAY IS STILL A SW
MONSOONAL DAY WITH MOISTURE MOVING UP FROM THE SW BUT ALSO
POTENTIALLY COMBINING WITH A FRONT THAT SLIDES DOWN FROM THE SOUTH
FOR AREAS EAST OF THE DIVIDE. THE GFS AND ECMWF AREA ALSO SHOWING
A SHORTWAVE ROTATING NEWD INTO THE WEST LATE IN THE DAY FRIDAY.
SCT THUNDERSTORMS LOOK GOOD FOR THE WEST...FOOTHILLS AND ALONG AND
BEHIND THE FRONT. FRONTAL BOUNDARY AND MOISTURE STAYS AROUND
THROUGH THE WEEKEND AS NW FLOW BEGINS TO DEVELOP. PW VALUES OF .75
TO 1 INCH SEEM VERY REASONABLE FOR FRIDAY THROUGH THE WEEKEND. THE
GFS IS HIGHER YET WITH A LARGE AREA OF OVER AN INCH ON FRIDAY.
MODELS THEN SHOW QUITE A BIT OF ENERGY RIDING OVER AND THROUGH THE
RIDGE AND GRADUALLY ERODING IT. THE DETAILS VARY QUITE A BIT BUT
IT LOOKS LIKE A POTENTIALLY VERY ACTIVE START TO NEXT WEEK WITH
COOLING MID LEVEL TEMPERATURES...ACTIVE SHORTWAVES MOVING THROUGH
THE FLOW...CONTINUED NE UPSLOPE FLOW AND CONSIDERABLE LOW LEVEL
MOISTURE. HIGH TEMPERATURES ALSO WILL LIKELY BE ON A DOWNWARD
TREND THROUGH THE PERIOD.

&&

.AVIATION.../12Z ISSUANCE/

AN AREA OF CIGS 110-130 MSL ACROSS CENTRAL WYOMING WILL GRADUALLY
DISSIPATE 10Z-14Z.  SFC HIGH PRESSURE OVER MT-NE WY WILL SLIDE SE
INTO THE CENTRAL HIGH PLAINS TODAY...KEEPING A PREVAILING EASTERLY
SFC FLOW EAST OF THE DIVIDE THOUGH WINDS WILL BE GENERALLY LIGHTER
NEAR 10KTS OR LESS.  A WEAK UPPER DISTURBANCE MAY RESULT IN A FEW
SHOWERS AND THUNDERSTORMS DEVELOPING ALONG THE EAST SLOPES OF THE
ABSAROKA AND BIGHORN RANGES LATE TUESDAY AFTERNOON AND TUESDAY
EVENING...HOWEVER A MORE STABLE CAPPED AIRMASS OVER THE BASINS WILL
KEEP MOST OF THIS ACTIVITY OVER THE HIGH TERRAIN.
&&

.FIRE WEATHER...

COOLER AIR FROM A SERIES OF CANADIAN COLD FRONTS WILL PUSH ACROSS
THE AREA THROUGH TODAY. 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. HIGH PRESSURE FROM
THE GREAT BASIN WILL BRING A WARM UP WITH A BETTER CHANCE OF SHOWERS
AND THUNDERSTORMS WEDNESDAY THROUGH FRIDAY ALTHOUGH PINPOINTING THE
MOST ACTIVE DAY IS STILL UNCERTAIN AT THIS POINT.
&&

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

$$

SHORT TERM...HATTINGS
LONG TERM...SKRBAC
AVIATION...AEM
FIRE WEATHER...HATTINGS







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