Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 020510
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1110 PM MDT SUN MAY 1 2016

.SHORT TERM...TONIGHT THROUGH MONDAY (ISSUED AT 120 PM MDT)

GENERAL BROAD LW TROF ACROSS THE CONUS WITH A COUPLE OF EMBEDDED
TROF/CLOSED LOWS STIRRING THE POT WITHIN. THE LOW MOST SIGNIFICANT
FOR THE FA IS QUITE BROAD AND LOCATIONS OVR THE SRN GREAT BASIN AND
MOJAVE DESERT REGION. OVR/NEAR WY...UPR RIDGE IS ACTUALLY FOLDING
INTO NRN PORTIONS OF THE STATE...DRYING THE MID AND UPR ATMOSPHERE
AND PUTTING THE KABASH ON MOST PRECIP ACROSS THE AREA. FROM CNTRL
WY SWD...A FEW LINGER AREAS OF VERY LIGHT SHOWERS ARE ALL THAT
REMAIN OF THE STORM SYSTEM OF THE PAST FEW DAYS. SFC SHOWS HIGH P
BUILDING INTO THE ERN 2/3RDS OF WY...WITH LOW P OVR THE GREAT
BASIN...AND BRISK ERLY WINDS BLOWING ACROSS THE SRN PORTIONS OF THE
STATE.

TODAY WILL BE HIGHLIGHTED BY THE FOLDING RIDGE AND DRYING ACROSS THE
FA FROM N TO S THROUGH THE DAY...WITH ONLY A FEW LINGERING MORNING
SHOWERS GIVING WAY TO A SPURIOUS INSTABILITY SHOWER OR TWO...MAINLY
IN THE BIGHORN...LARAMIE...OR MEDICINE BOW MOUNTAINS LATER THIS
AFTERNOON. OTHERWISE...A WARM UP BEGINS...WITH HIGHS REACHING INTO
THE 40S TO MID 50S ACROSS THE LOWER ELEVATIONS TODAY...WITH 30S AND
40S IN THE MOUNTAINS. MONDAY...UPR LOW ACROSS THE DESERT SW GETS
ABSORBED INTO THE FLOW...WHILE AN AMPLIFYING RIDGE BUILDS OVR THE
WRN CONUS...FURTHER PUSHING MOISTURE OUT OF THE REGION. IT WILL WARM
INTO THE 50S AND 60S WHILE REMAINING 99 PERCENT DRY MONDAY...EXCEPT
FOR A VERY SLIGHT POSSIBILITY FOR AN ISOLATED SHOWER OVR THE BIGHORN
OR CASPER MOUNTAINS...OR NEAR THE EXTREME SRN PORTION OF WY WHICH
WILL BE CLOSEST TO THE REMAINING BUT DWINDLING MOISTURE POOL.

.LONG TERM...MONDAY NIGHT THROUGH SUNDAY

DRYING OCCURS FROM NORTH TO SOUTH AS A DRY SURFACE HIGH PRESSURE
AREA MOVES SOUTH FROM ALBERTA ON MONDAY NIGHT.  AS AN UPPER LEVEL
HIGH PRESSURE RIDGE BUILDS INTO THE WEST...SIGNIFICANT DRYING AND
WARMING OCCURS TUESDAY THROUGH THURSDAY. TEMPERATURES WILL BE 6
TO10DEGREES ABOVE NORMAL MOST AREAS.  WHEN THE RIDGE AXIS MOVES INTO
EASTERN WYOMING...SOUTH SOUTHWEST FLOW MOVES INTO WESTERN WYOMING
WITH SOME SHOWERS DEVELOPING WEDNESDAY NIGHT AND THURSDAY OVER THE
WESTERN MOUNTAINS. THE SPREAD BETWEEN THE MODEL SOLUTIONS BECOMES
QUITE LARGE...BUT WITH A GENERAL LONG WAVE HIGH PRESSURE RIDGE...THE
MAIN DIFFERENCES ARE TO THE WEST AND EAST OF THE AREA WHERE LONG
WAVE TROUGHS BRACKET THE RIDGE. WEDNESDAY AND THURSDAY HIGHS WARM
NICELY INTO THE UPPER 60S AND 70S WITH THE WARMEST TEMPERATURES IN
THE BIGHORN BASIN.  SHOWERS EXPECTED TO BECOME SCATTERED OVER THE
WESTERN MOUNTAINS WITH ISOLATED THUNDERSTORMS DUE TO HEATING. SHOULD
HAVE ENOUGH RESIDUAL MOISTURE ON THE GROUND TO EVAPORATE AND PROVIDE
NEEDED MOISTURE FOR CONVECTION...AS THE PACIFIC TROUGH DIGS INTO THE
GREAT BASIN ON FRIDAY. YET ANOTHER CUT OFF LOW...WITH UPLSOPE FLOW
EAST TO NORTHEAST FLOW WILL RETURN TO THE AREA WITH COOLING
TEMPERATURES AND INCREASED MOISTURE AND LIFT SUPPORTING A RETURN TO
AREAS OF SNOW AND RAIN MOVING INTO FRIDAY AND SATURDAY. TEMPERATURES
EXPECTED TO COOL SIGNIFICANTLY ON SATURDAY AS SHOWERS BECOME MORE
WIDESPREAD AND EAST TO NORTHEAST UPSLOPE FLOW DEEPENS AND MOISTENS.
SNOW LEVEL SHOULD START OUT AROUND 9000 FEET WITH A RAIN SNOW MIX
DOWN TO 7500 FEET.  SUNDAY SHOULD SEE DECREASING PRECIPITATION WITH
COLD BELOW NORMAL TEMPERATURES.  MODEL SOLUTIONS ARE QUITE DIVERGENT
WITH THE EVOLUTION OF THE UPPER LEVEL LOW WHICH SIGNIFICANTLY
DECREASES THE CONFIDENCE IN THE TIMING OF THE DECREASE IN
PRECIPITATION.

&&

.AVIATION.../06Z ISSUANCE/

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

VFR CONDITIONS TO OCCUR THROUGH THE FORECAST PERIOD.

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

VFR CONDITIONS TO OCCUR THROUGH THE FORECAST PERIOD.

&&

.FIRE WEATHER...

TODAY...LOW FIRE DANGER FOR ALL LOCATIONS CONTINUES WITH HIGH
MINIMUM RH VALUES ONLY BOTTOMING OUT IN THE 30S TO MID 60S (PERCENT)
ACROSS THE ENTIRE REGION. ISOLATED LINGERING SHOWERS WILL CONTINUE
TO DISSIPATE ACROSS WYOMING TODAY.  WINDS WILL BE QUITE GUSTY ACROSS
THE SOUTHERN PORTION OF WYOMING TODAY. MONDAY GREEN UP WILL BEGIN IN
EARNEST UNDER WARMING AND DRYING CONDITIONS EVERYWHERE. MINIMUM RH
VALUES WILL DROP INTO THE 20S TO PERHAPS THE UPPER TEENS (PERCENT)
FOR MANY LOCATIONS. HOWEVER...WITH RELATIVELY LIGHT WIND AT ALL
LOCATIONS...FIRE DANGER WILL REMAIN LOW.

&&

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

&&

$$

SHORT TERM...BRAUN
LONG TERM...C.BAKER
AVIATION...AR
FIRE WEATHER...BRAUN



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