Area Forecast Discussion
Issued by NWS Boise, ID

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247
FXUS65 KBOI 011521
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
921 AM MDT SUN MAY 1 2016

.DISCUSSION...SEVERAL DEGS WARMER EACH DAY THROUGH WEDNESDAY.
INITIALLY...EAST WINDS ALOFT BETWEEN UPPER HIGH IN SWRN CANADA AND
UPPER LOW IN ARIZONA.  AT THE SURFACE...DOWNSLOPE EAST/SE WINDS DUE
TO SURFACE HIGH PRESSURE CENTERED IN MONTANA.  ON MONDAY THE ARIZONA
UPPER LOW WILL MOVE INTO THE PLAINS STATES WHILE THE UPPER HIGH
STAYS JUST NORTH OF ID/MT. BY WEDNESDAY A PACIFIC TROUGH AND WARMER/
MOISTER SOUTH WINDS ALOFT WILL COME INLAND.  THE CHANCE OF SHOWERS
AND THUNDERSTORMS WILL THEN INCREASE IN OUR AREA.  THE UPPER HIGH
WILL WEAKEN AND SHIFT EAST.  COOLING WILL BEGIN THURSDAY AS THE
PACIFIC UPPER TROUGH COMES FURTHER INLAND.  CURRENT FORECAST LOOKS
GOOD...NO UPDATES.

&&

.AVIATION...ISOLATED SHOWERS IN THE BOISE MOUNTAINS AFTER 18Z...
OTHERWISE VFR WITH FEW TO SCATTERED MID-LEVEL CLOUDS. SURFACE WINDS
GENERALLY 12 KNOTS OR LESS THIS MORNING...BECOMING EASTERLY 5-15
KNOTS THIS AFTERNOON. WINDS ALOFT EAST TO SOUTHEAST 10-20 KNOTS UP
THROUGH 10K FEET MSL.

&&

.PREV DISCUSSION...
SHORT TERM...TODAY THROUGH MONDAY...AN UPPER RIDGE WILL MOVE INLAND
ACROSS THE PACIFIC NORTHWEST AND NORTHERN ROCKIES TODAY AND MONDAY
...WITH AN UPPER HIGH BECOMING CENTERED JUST ACROSS THE CANADIAN
BORDER. MEANWHILE...A TROUGH CURRENTLY OVER THE SOUTHWEST STATES
WILL GRADUALLY WEAKEN. THIS PATTERN WILL CREATE EASTERLY FLOW AT THE
SURFACE AND ALOFT ACROSS THE FORECAST AREA.  WARMING AND DRYING WILL
OCCUR IN THIS PATTERN WITH JUST A SLIGHT CHANCE OF SHOWERS OVER THE
BOISE MOUNTAINS THIS AFTERNOON...AND OVER THE BOISE AND WEST CENTRAL
MOUNTAINS MONDAY AFTERNOON. NOT NEARLY AS BREEZY TODAY WITH WINDS
OUT OF THE EAST.

LONG TERM...MONDAY NIGHT THROUGH SATURDAY...A HIGH-AMPLITUDE UPPER
RIDGE WILL MOVE SLOWLY EAST...FROM THE ROCKIES EARLY IN THE WEEK TO
THE CENTRAL U.S. BY THE END OF THE WEEK. THE RIDGE WILL SLOW DOWN
THE PROGRESSION OF THE NEXT PACIFIC TROUGH...WHICH WILL EVENTUALLY
BECOME A LARGE UPPER LOW CENTERED OVER SOUTHERN CALIFORNIA TOWARD
THE END OF THE WEEK. AHEAD OF THE TROUGH...SOUTHERLY FLOW WILL BRING
TEMPERATURES TO WELL ABOVE NORMAL TUESDAY AND WEDNESDAY. MOISTURE
NEAR THE LEADING EDGE OF THE TROUGH WILL LEAD TO AN INCREASING
CHANCE OF SHOWERS/SLIGHT CHANCE OF AFTERNOON THUNDERSTORMS IN SE
OREGON...WITH A SLIGHT CHANCE OF SHOWERS/AFTERNOON THUNDERSTORMS
OVER THE HIGHER TERRAIN OF SW IDAHO...BY MIDWEEK. MOISTURE WILL WRAP
INTO THE AREA AROUND THE NORTHERN PERIPHERY OF THE LARGE CLOSED LOW
PRESSURE SYSTEM AS IT DIGS INTO SOUTHERN CALIFORNIA AND THEN DRIFTS
NORTHEASTWARD INTO THE GREAT BASIN BY SATURDAY. PRECIPITATION
CHANCES WILL REMAIN ABOVE NORMAL THURSDAY THROUGH SATURDAY...WITH A
CHANCE OF MOUNTAIN SHOWERS/SLIGHT CHANCE OF VALLEY SHOWERS AND A
SLIGHT CHANCE OF AFTERNOON THUNDERSTORMS. TEMPERATURES WILL BE
SLIGHTLY COOLER...BUT STILL ABOVE NORMAL.

&&

.HYDROLOGY...THE BRUNEAU AND JARBIDGE RIVERS CONTINUE TO RUN HIGH
IN OWYHEE COUNTY. ABOVE AVERAGE SNOWPACK EXISTS IN THE UPPER BRUNEAU
BASIN...PARTICULARLY IN THE JARBIDGE RIVER WATERSHED. WARMER
TEMPERATURES THIS WILL WEEK WILL ACCELERATE SNOWMELT AND KEEP THE
RIVERS RUNNING HIGH. RIVERS AND CREEKS IN THESE BASINS WILL NEED TO
BE MONITORED AS THEY RESPOND TO THE INCREASED RUNOFF.

&&

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

&&

$$

WWW.WEATHER.GOV/BOISE
WWW.FACEBOOK.COM/NWSBOISE
WWW.TWITTER.COM/NWSBOISE

DISCUSSION...LC
AVIATION.....JA
PREV SHORT TERM...TL
PREV LONG TERM....BW
HYDROLOGY...TL



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