Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 232007
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
207 PM MDT TUE JUN 23 2015

.SHORT TERM...TONIGHT THROUGH WEDNESDAY

WV IMAGERY SHOWS FLAT RIDGING OVR THE WEST...WITH A COUPLE OF
EMBEDDED SWS MOVING THRU THE FLOW...ONE OVR NRN WY...ANOTHER JUST
UPSTREAM WITH AXIS STRETCHING FROM ERN WA TO ERN OR. SFC HAS WEAK
LOW P BUILDING ACROSS SRN WY...HIGH P WELL OFF TO THE E OVR THE
PLAINS WITH A BOUNDARY/WEAK FRONT IN BETWEEN FROM NRN WY TO SERN WY.

VERY WARM TO HOT UNDER MODEST TO FLAT RIDGING...BUT WITH RISING
HEIGHTS. SMALL/LEADING SW CURRENTLY MOVING ACROSS THE NW FA. NRN
MOUNTAINS AND DEVELOPING LOW AND ATTENDANT BOUNDARY (WARM)FRONT WILL
BE AREA TO FOCUS ON FOR CI LATER TODAY/TONIGHT. EXPECT ONLY ISOLATED
STORMS AT BEST WITH FAIRLY WIDESPREAD CAPPING IN PLACE...WIDELY
SCATTERED TO THE E AND NE OF THE FA. WITH ML CAPE IN THE 1500 TO
2000 J/KG RANGE AND EFFECTIVE SHEAR OF 40 TO 50 KTS...ESPECIALLY
NEAR THE LL RETURN FLOW (ERLY/NERLY) AROUND THE NWD MOVING FRONT IN
JOHNSON COUNTY. GENTLE CLOCKWISE HODOGRAPH WILL GIVE SLIGHT
PREFERENCE TO RIGHT MOVERS TODAY. IF A STORM DOES GO UP IT COULD BE
STRONG WITH HAIL TO .75 INCH AND STRONG WIND GUSTS APPROACHING
SEVERE BEFORE IT MOVES OUT OF THE CWA TO THE EAST. WHILE STORMS WILL
BE ROTATING WELL ENOUGH...TORNADO THREAT SEEM RELATIVELY LOW WITH
RELATIVELY SMALL LL SHEAR AND LCLS ON THE HIGH SIDE. THE SECOND
(UPSTREAM) SW WILL THEN MOVE ACROSS THE CWA LATER TONIGHT...HELPING
TO DEVELOP AND EVENTUALLY PUSH FRONT BACK SWD ON WED. BEFORE THAT
HOWEVER...MID LVL FRONT DEVELOPMENT WITH LL JET TO THE SOUTH WILL BE
THE LIKELY LOCATION FOR MCS FORMATION LATE TONIGHT/THRU WED
MORNING...MAINLY EAST OF THE FA.

WED...SIMILAR SET-UP TO THAT OF TODAY BY LATE IN THE
AFTERNOON/EVENING WITH A LITTLE BETTER SFC TO MID LVL FORCING N OF
THE FRONT INTO JOHNSON COUNTY...MAKING IT SLIGHTLY EASIER FOR CI TO
OCCUR AND ISOLATED TO WIDELY SCATTERED STORMS TO FORM ACROSS NRN
JOHNSON...FROM THE BIGHORNS EWD TO THE BORDER. ATTM...BEST AREA FOR
STRONG/SEVERE STORMS LOOKS TO LAY ON OR JUST E OF THE JOHNSON COUNTY
BORDER. WINDS BACKING FROM SFC TO ALOFT AND SLIGHT CLOCKWISE TO
STRIGHTLINE HODOGRAPHS WILL GIVE LARGELY MIXED MODE CONVECTION WITH
SPLITTING STORMS A POSSIBILITY...ALONG WITH NEAR SEVERE HAIL/WINDS
FOR A SHORT PERIOD.


.LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY

THE CONVECTION OF WEDNESDAY AFTERNOON SHOULD LINGER INTO THE
EVENING...ESPECIALLY ACROSS EASTERN PORTIONS OF THE COUNTY WARNING
AREA. MODELS ARE EVEN SHOWING IT LINGER INTO THE LATE WEDNESDAY
NIGHT HOURS WITH THE POSSIBLE DEVELOPMENT OF AN MCS IN PORTIONS OF
NATRONA AND ESPECIALLY JOHNSON COUNTY. AS A RESULT...WE INCREASED
POPS A BIT IN THAT AREA. AS FOR THURSDAY...WITH THE BOUNDARY
REMAINING IN THE AREA WE MAINTAINED THE CHANCE OF
THUNDERSTORMS...ONCE AGAIN THE BEST CHANCE IN EASTERN AREAS WHERE
THE BEST CAPE AND CONVERGENCE WILL BE. WITH MORE CLOUD COVER WE ALSO
LOWERED TEMPERATURES A COUPLE OF DEGREES...ALTHOUGH IT WILL STILL BE
A VERY WARM DAY.

FOLLOWING THAT...WE LOOK TO ENTER A WASH...RINSE...REPEAT CYCLE. THE
REASON IS A STRONG RIDGE OF HIGH PRESSURE...A BOILER PLATE RIDGE AS
ONE OF MY FORMER COLLEAGUES USED TO CALL IT...BUILDS ACROSS THE
NORTHERN ROCKIES. THAT MEANS A PATTERN OF HOT TEMPERATURES FOR MOST
LOCATIONS...90S WILL BE COMMONPLACE STARTING THIS WEEKEND AND
ESPECIALLY EARLY NEXT WEEK WHEN THE HEAT IS EXPECTED TO PEAK. THE
WARMER LOCATIONS IN THE BIG HORN BASIN SUCH AS GREYBULL AND WORLAND
COULD EVEN SEE THE DREADED TRIPLE DIGITS FOR HIGH TEMPERATURES EARLY
NEXT WEEK. AS FOR ANY CHANCE OF CONVECTION...WITH THE HIGH HEIGHTS
FROM THE STRONG RIDGE THUNDERSTORMS ARE EXPECTED TO BE FEW AND FAR
BETWEEN. ANY THAT DO DEVELOP WOULD BE OF THE HIGH ELEVATION HEAT
SOURCE VARIETY ACROSS THE MOUNTAINS. BUT EVEN HERE...WITH LIMITED
MOISTURE COVERAGE SHOULD BE FAIRLY SPARSE. AND...WITH MAINLY LIGHT
STEERING FLOW EXPECTED...THE CHANCE ANY COULD DRIFT INTO THE LOWER
ELEVATIONS OTHER THAN MAYBE THE ADJACENT FOOTHILLS LOOKS SLIM TO
NONE AT THIS TIME.
&&

.AVIATION.../00Z ISSUANCE/

VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST PERIOD. AN ISOLATED
THUNDERSTORM OR TWO WILL BE POSSIBLE ACROSS FAR NORTHERN WY AND OVR
NORTHERN JOHNSON COUNTY...INCLUDING VCNTY KCOD AND KBYG THIS
EVENING. DRY THROUGH THE REST OF OF THE FORECAST. GUSTY WEST TO
SOUTHWEST WINDS THROUGH 03Z SOUTH OF AND VCNTY KLND TO KCPR LINE.

&&

.FIRE WEATHER...

FIRE DANGER WILL REMAIN BELOW CRITICAL FOR ANOTHER DAY OR SO AS THE
AREA REMAINS IN GREEN-UP. HOWEVER...FIRE DANGER WILL BE ENHANCED
BOTH TODAY AND TOMORROW ACROSS THE SOUTHERN HALF OF THE FORECAST
AREA AS HOT DAY TIME TEMPERATURES CONTINUE WITH MINIMUM RH VALUES IN
THE LOWER TEENS...COMBINING WITH WINDS OCCASIONALLY GUSTING TO
AROUND 25 MPH THROUGH EARLY EVENINGS. NO PRECIPITATION EXPECTED
ACROSS MOST OF THE FORECAST AREA EXCEPT FOR SMALL CHANCES OVR THE
FAR NORTHERN AND NORTHEASTERN ZONES WHERE ISOLATED TO WIDELY
SCATTERED STORMS WILL BE POSSIBLE.

&&

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

$$

SHORT TERM...BRAUN
LONG TERM...HATTINGS
AVIATION...BRAUN
FIRE WEATHER...BRAUN


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