Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 031550
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
950 AM MDT SUN MAY 3 2015

.DISCUSSION...MORNING WATER VAPOR SATELLITE PICS SHOWING A WEAK
FEATURE MOVING THROUGH NE NV AND S-CENTRAL ID THIS MORNING. THIS
HAS BROUGHT SOME EARLY MORNING SHOWERS ACROSS THE SNAKE RIVER
PLAIN AND BOISE MTNS. WEB CAM IMAGES SHOWING MOST OF THE ACTIVITY
IS VIRGA WITH THE HEAVIER SHOWERS POSSIBLY GETTING LIGHT RAIN TO
THE SURFACE. THIS FEATURE AND ACCOMPANYING SHOWER ACTIVITY WILL
MOVE EAST OF THE AREA BY AFTERNOON...ONLY TO BE REPLACED BY
DIURNALLY DRIVEN CONVECTIVE DEVELOPMENT. HAVE SEEN A SLIGHT
INCREASE IN MID-LEVEL MOISTURE SINCE YESTERDAY AND WITH SIMILAR
AFTERNOON HEATING THERE WILL BE ANOTHER ROUND OF AFTERNOON SHOWERS
AND THUNDERSTORMS OVER HIGHER TERRAIN SOUTH OF THE SNAKE RIVER AND
ACROSS FAR SE OREGON NEAR THE NV BORDER. AND LIKE YESTERDAY
ACTIVITY WILL PULSE WITH THE BIGGEST THREAT BEING GUSTY WINDS
/SPEEDS TO 45 MPH POSSIBLE/. HAVE UPDATED THE AFTERNOON/EVENING
FORECAST TO INCLUDE SHOWERS AND STORMS IN SE OREGON AND INTRODUCE
A SLIGHT CHANCE INTO THE S-CENTRAL SNAKE PLAIN NEAR TWIN FALLS.

&&

.AVIATION...VFR UNDER SCATTERED MID-HIGH CLOUDS. ISOLATED SHOWERS
OVER THE BOISE MTNS EXPECTED TO DIE OFF BY 4/0Z...WITH SLIGHT CHANCE
THUNDERSTORMS BETWEEN 3/18Z AND 4/0Z. ISOLATED SHOWERS AND
THUNDERSTORMS ALSO EXPECTED TO DEVELOP OVER SOUTHERN SE OREGON AND
SOUTHERN SW IDAHO THIS AFTERNOON...TAPERING OFF BY 4/3Z. SURFACE
WINDS...12 KTS OR LESS WITH SOME GUSTS TO 15 KTS IN THE SNAKE
RIVER VALLEY THIS AFTERNOON. GUSTS POSSIBLE NEAR TODAY/S
THUNDERSTORMS AS WELL. WINDS ALOFT NEAR 10K FT MSL...W 5-15
KTS...BECOMING SW AFTER 4/12Z.

&&

.PREV DISCUSSION...
SHORT TERM...TODAY THROUGH MONDAY...WESTERLY FLOW ALOFT WILL
REMAIN OVER THE AREA TODAY. TEMPERATURES WILL BE SIMILAR TO
YESTERDAY WITH HIGHS MAINLY IN THE 70S...OR ABOUT 10 DEGREES ABOVE
NORMAL. MOISTURE AND INSTABILITY WILL CONTINUE NEAR THE NEVADA
BORDER FOR ISOLATED SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND
EVENING. BEST POTENTIAL WILL BE IN FAR SOUTHERN TWIN FALLS
COUNTY. DEEP CLOSED UPPER LOW IN THE GULF OF ALASKA WILL APPROACH
THE PACIFIC NORTHWEST ON MONDAY. AS IT DOES...THE FLOW WILL CHANGE
MORE SOUTHWESTERLY ALLOWING TEMPERATURES TO BE A SLIGHTLY WARMER
WITH LOWER 80S EXPECTED IN THE TREASURE VALLEY. THIS WILL ALSO
ALLOW THE MOISTURE TO SHIFT NORTHWARD. HOWEVER...MOISTURE WILL
REMAIN LIMITED FOR CONVECTION BUT WILL KEEP A SLIGHT CHANCE OF
AFTERNOON SHOWERS/THUNDERSTORMS PRIMARILY NEAR THE NEVADA BORDER.
WINDS WILL REMAIN LIGHT...EXCEPT GUSTY WINDS ARE POSSIBLE IN THE
VICINITY OF THUNDERSTORMS.

LONG TERM...MONDAY NIGHT THROUGH SATURDAY...LATEST MODEL RUNS
REMAIN IN FAIRLY GOOD AGREEMENT WITH THE WEATHER PATTERN THROUGH
THE EXTENDED.  THE LAST SEVERAL DAYS THERE WERE DIFFERENCES IN
THE MODELS BUT THE ECMWF HAS FOR THE LAST 4 RUNS COME TO THE SAME
SOLUTION AS THE GFS.  WHILE FORECASTER CONFIDENCE IS INCREASING
IN THE MODELS STILL HAVE SOME DOUBT WITH THE OUTCOME OF THE
WEATHER FOR THE FORECAST AREA.  IN GENERAL A DEEP UPPER LEVEL LOW
WILL MOVE INTO THE PACIFIC NORTHWEST MONDAY NIGHT AND TUESDAY THEN
CARVE OUT A LONG WAVE TROUGH OVER THE INTERMOUNTAIN WEST TUESDAY
NIGHT WITH THE BASE OF THE TROUGH CONTINUING TO DIG TO THE SOUTH
THROUGH THE END OF WEEK AND INTO THE WEEKEND.  AS THIS TROUGH
DIGS TO THE SOUTH IT WILL SPLIT WITH THE NORTHERN SECTION MOVING
QUICKLY TO THE NORTHEAST WHILE THE SOUTHERN SECTION SINKS TO THE
SOUTH.  EVEN WITH MODELS IN RELATIVELY GOOD AGREEMENT THERE ARE
DIFFERENCES AS TO WHERE AND WHEN PRECIPITATION WILL FALL.  WITH
THE DIFFERENCES IN THE MODELS WILL KEEP DAILY SHOWERS OVER THE
HIGHER TERRAIN THROUGH THE EXTENDED WITH AFTERNOON AND EVENING
THUNDERSTORMS.  IF MODELS CONTINUE THE CURRENT TREND COULD SEE
SHOWERS SPREAD TO MOST OF THE FORECAST AREA THURSDAY AND FRIDAY.
TEMPERATURES THROUGH THE EXTENDED PERIOD WILL AVERAGE 5-10
DEGREES BELOW NORMAL.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.

&&

$$

WEATHER.GOV/BOISE

DISCUSSION...DG
AVIATION.....AB
PREV SHORT TERM...BW
PREV LONG TERM....JA


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