960
FXUS65 KBOI 242058
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
258 PM MDT THU JUL 24 2008
SHORT TERM...TONIGHT THROUGH SATURDAY
DRY SOUTHWEST FLOW WILL
CONTINUE ALOFT OVER SE OREGON AND SW IDAHO IN THE SHORT TERM. THIS
OCCURS AS AN EXPANSIVE HIGH ALOFT TRANSITIONS SLIGHTLY CLOSER...FOR
WARMING...FROM BEING CENTERED OVER NORTH TEXAS TO THE FOUR-CORNERS
REGION. A THIN LAYER OF HIGH ALTITUDE MOISTURE CROSSES THE SOUTH
CENTRAL MOUNTAINS FRIDAY AFTERNOON. WHILE INSTABILITY IS GREATER
THAN 200 J/KG AND LIS ARE NON-POSITIVE...A TRIGGER IS HARD TO
FIND. SO LEFT A MENTION OF THUNDER OUT FOR NOW THERE. THE OPPOSITE
IS TRUE IN NE VALLEY COUNTY WHERE WEAK FORCING /H7 CONVERGENCE-H3
DIVERGENCE/ CROSSES LIMITED INSTABILITY. THE AREA IS QUITE SMALL
AND WELL EAST OF MCCALL. THESE FAR NE AND S CENTRAL AREAS HAVE A
THIN LAYER OF MOISTURE SATURDAY AFTERNOON/EVENING...INSTABILITY IS
EVEN LESS AND NO LARGE SCALE FORCING WAS NOTED IN THE GFS/NAM12
SO WENT WITH A DRY /AND HOT/ FORECAST.
LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
MODELS IN GOOD
AGREEMENT DURING THE FIRST TWO DAYS OF THIS PERIOD AND KEEP AN
INTENSE HIGH PRESSURE RIDGE ALOFT ORIENTED EAST TO WEST ACROSS THE
SOUTHERN HALF OF THE NATION. THIS PATTERN ESSENTIALLY PREVENTS
TROPICAL SYSTEM DOLLY MOISTURE FROM COMING THIS FAR NORTH AND WEST.
BUT THIS MOISTURE DOES GET TRAPPED UNDER THE RIDGE IN THE SOUTHWEST
AND WILL EVENTUALLY GET CARRIED AWAY BACK EAST LATER NEXT WEEK. FOR
OUR AREA...CONDITIONS REMAIN DRY AND SEASONALLY HOT THROUGH MUCH OF
THE EXTENDED PERIOD WITH THE CORE OF THE HEAT AFTER SUNDAY CENTERED
OVER THE ROCKIES AND THE MIDWEST. MEANWHILE...A FAIRLY STRONG
NORTHERN BRANCH OF WESTERLIES FOR LATE JULY KEEPS PRESSING INTO THE
PACIFIC NORTHWEST WITH PERIODIC SHORT WAVES FROM TIME TO TIME.
ALTHOUGH IT REMAINS DRY IN OUR AREA THROUGH THE PERIOD...THESE SHORT
WAVES RIDING THROUGH THE NORTHERN STREAM FLOW WILL PREVENT OUR AREA
FROM GETTING INTO EXCESSIVE HEAT...BUT RATHER KEEP SEASONAL
TEMPERATURES OVER THE AREA. ANY MOISTURE WITH THESE PACIFIC WAVES
APPEARS TO BE CONFINED TO THE NORTHERN PART OF THE PACIFIC NORTHWEST
ALONG THE CANADIAN BORDER.
AVIATION....AVIATION
VFR CONDITIONS WITH CLEAR SKIES AND LIGHT
DIURNAL WINDS THROUGH FRIDAY. HAZE EXPECTED TO BECOME THICKER ONCE
AGAIN TONIGHT AND EARLY FRIDAY AS MIXING SLOWS DOWN AND VENTILATION
BECOMES POORER. LOCALLY...IFR FOG IS POSSIBLE IN THE LONG VALLEY OR
IN OTHER SHELTERED MOUNTAIN VALLEYS AFTER 10Z BUT SHOULD LAST FOR
ONLY A SHORT TIME THRU ABOUT 14Z THEN DISSIPATE.
BOI WATCHES/WARNINGS/ADVISORIES
ID...NONE.
OR...NONE.
WEATHER.GOV/BOISE
SHORT TERM...VM
LONG TERM....GS/DD
AVIATION.....GS
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