Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 280504
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1104 PM MDT WED APR 27 2016

.SHORT TERM...TONIGHT THROUGH THURSDAY (ISSUED AT 305 PM MDT)

A CHUNK OF THE MAIN CIRCULATION APPEARS TO BE OVER SOUTH
CENTRAL NEBRASKA WITH A PIECE OF ENERGY RETROGRADING WEST ALONG
THE NEBRASKA SOUTH DAKOTA BORDER FROM THE DEFORMATION ZONE. FOR
NOW...WE ARE STILL EXPERIENCING RAIN/SNOW BANDING UNDER THE MID
LEVEL NW FLOW AROUND THE BACKSIDE OF THIS WEATHER COMPLEX.
HOWEVER...SFC WINDS HAVE RESUMED A PREDOMINANTLY NE DIRECTION SO
MUCH OF THE SHOWER ACTIVITY IS BEGINNING TO BANK UP AGAINST JUST
NE OF THE FTHLS OF THE DVD DUE TO SFC CONVERGENCE. LIGHT SHOWERS
ARE ALSO EVIDENT IN THE BIG HORN BASIN. THESE SHOWERS HAVE
DIMINISHED TO JUST LIGHT PRECIP. IN THE MEANTIME...THE
AFOREMENTIONED RETROGRADING PIECE OF ENERGY WILL CONTINUE TO MOVE
WEST ALONG THE MT/WY BORDER THROUGH THURSDAY.AS IT DOES...IT WILL
DRIVE A SECONDARY REINFORCING SURGE OF COOL MOIST AIR SOUTH
TONIGHT. THIS WILL PROLONG THE RAIN AND SNOW SHOWERS...MAINLY
OVER THE NORTH HALF OF THE AREA...ESP IN THE MTNS TONIGHT AND INTO
THU. TEMPS WILL BE MILDER THU BUT STILL ON THE COOL SIDE. THE NEXT
LOW PRESSURE CENTER NOSING SOUTHWEST INTO THE HEART OF CALIFORNIA
WILL BE PUSHING SOME ENERGY NORTH AHEAD OF IT INTO EXTREME
SOUTHERN SWEETWATER COUNTY THURSDAY AFTERNOON FOR ADDITIONAL
SHOWER ACTIVITY THERE. THE LOWEST POPS WILL BE OVER THE SOUTHERN
HALF OF OUR CWA THU IN THE COL REGION BETWEEN SYSTEMS.

.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY

SLOW MOVING 3 WAVE PATTERN ACROSS THE NH WILL KEEP WY GENERALLY ON
THE COOL SIDE AND MOIST WITH INTERJECTIONS OF INSTABILITY FROM SOUTH
OF THE REGION...AS DISTURBANCES DIVE RATHER DEEPLY SOUTH THRU THE
WRN CONUS OVER MUCH OF THE NEXT WEEK. THIS WILL RESULT IN NEARLY
PERPETUAL LOW/SLIGHT CHCS OF PRECIP ACROSS THE FA THRU AT LEAST TUE
MORNING...PARTICULARLY ACROSS THE SRN HALF OF THE FA. BETTER CHANCE
PRECIPITATION EPISODES WILL BE EMBEDDED THU NIGHT ACROSS THE SOUTH
AND SOUTHWEST AS A WEAK CLOSED LOW SETTLES OVR/NEAR THE 4
CORNERS...FRIDAY AFTERNOON/FRIDAY EVENING ACROSS THE WRN MOUNTAINS
AND ERN FA  AS THE UPR TROF/LOW SLOWS DOWN AND BECOMES NEGATIVELY
TILTED OVR THE REGION...AND AGAIN SATURDAY AFTERNOON AND EVENING AS
THE MAIN UPR LOW SLIDES E OVR THE CNTRL PLAINS AND TOGETHER WITH THE
SFC PORTION OF THE LOW TRIES TO PUMP SOME RETURN MOISTURE BACK INTO
ERN/CNTRL FA. SUNDAY...SHOWERS...BOTH LIQUID AND FROZEN...WILL TAPER
OFF BY AFTERNOON. AFTER THAT...MDL DIVERGENCE REALLY BEGINS TO TAKE
PLACE UNTIL THE END OF THE FCST PERIOD AS THEY TRY TO FIGURE OUT
WHICH PORTION OF THE UPR LVL FLOW TO ABSORB THE BROAD UPR LOW INTO.
BOTTOM LINE...THE GFS TENDS A LITTLE WETTER AND COOLER MONDAY AND
TUESDAY UNDER A MORE GENTLY CHANGING UPR LVL PATTERN...WHILE THE
EURO KEEPS PRECIP FURTHER S AND MOSTLY OUT OF THE FA...WITH A MORE
AMPLIFIED RIDGE AND DRYING PATTERN GETTING HERE EARLIER. BOTH MDLS
THEN SEEM TO CATCH UP WITH EACH OTHER BY WEDNESDAY WITH RESPECT TO
RIDGING...WITH A MOSTLY WARM/DRY DAY ACROSS THE CWA...AND PERHAPS
ONLY A FEW DIURNAL ISOLATED -SHRA/-TSRA ACROSS THE WRN MOUNTAINS IN
THE AFTERNOON. HOWEVER...A BLOCKING PATTERN LOOKS TO POSSIBLY BE ON
THE WAY INTO THE CONUS BEYOND THE FCST PERIOD TOWARDS THE END OF
NEXT WEEK. WE WILL SEE WHAT HAPPENS AND IF COOL...POSSIBLY WET
CONDITIONS...ARE BACK FOR AN EXTENDED PERIOD

&&

.AVIATION.../06Z ISSUANCE/

WEST OF THE CONTINENTAL DIVIDE...KJAC/KRKS/KPNA/KBPI AIRPORTS

VFR CONDITIONS WILL PREVAIL OVER MOST OF THE REGION THROUGH THURSDAY
NIGHT. LOW CLOUDS WILL PRODUCE MVFR CONDITIONS THROUGH 16Z IN
SOUTHWEST WY. SOME SHOWERS WILL DEVELOP OVER SOUTHWEST WY THURSDAY
AFTERNOON AND EVENING. AREAS OF MVFR CONDITIONS WILL DEVELOP IN
SOUTHWEST WY BY 00Z FRI THROUGH 06Z FRI. A GUSTY NORTHEAST WIND AT
THE KRKS AIRPORT MOST OF THURSDAY INTO THURSDAY EVENING.

EAST OF THE CONTINENTAL DIVIDE...KCPR/KCOD/KRIW/KWRL/KLND AIRPORTS

MVFR TO IFR CIGS OVER MOST OF THE REGION THROUGH 18Z. SOME LIGHT
RAIN AND SNOW AS WELL THROUGH 15Z. MVFR TO VFR CIGS WILL OCCUR AFTER
18Z THROUGH 02Z FRI. THEN LOWER CLOUDS WILL RETURN TO CENTRAL WY AS
WELL AS THE KCOD AREA WITH MVFR CIGS PREVAILING 06Z FRI.

&&

.FIRE WEATHER...

FEW CONCERNS FOR MOST OF THE WEEK WITH UPPER LEVEL LOW PRESSURE
KEEPING THE WEATHER UNSETTLED. TEMPERATURES WILL AVERAGE BELOW
NORMAL WITH RELATIVE HUMIDITY REMAINING ABOVE CRITICAL LEVELS...SOME
AREAS WELL ABOVE CRITICAL LEVELS. THERE WILL BE A DAILY CHANCE FOR
SHOWERS FROM TONIGHT LIKELY INTO THE WEEKEND FOR MANY AREAS.

&&

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

&&

$$

SHORT TERM...LIPSON
LONG TERM...BRAUN
AVIATION...AR
FIRE WEATHER...LIPSON



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