AREA FORECAST DISCUSSION
NWS BOISE IDAHO
AFDBOI 940 PM MST FRI MAR 5 2004
.DISCUSSION...NO UPDATES PLANNED THIS EVENING. LOW END SNOW
ADVISORY ALLOWED TO CONTINUE FOR BRIEF BURST OF SNOWS WITH FRONT AND
UPPER TROF PASSAGE. 00Z RAOBS/ACARS SHOW 130KT SPEED MAX OVER CWFA
DIVING SE...MORE PARALLEL TO SRN PART OF CDFNT BUT PUSHING NRN
PORTION THROUGH MT. COLD FRONT AT 9PM EXTENDS FROM NW BAKER COUNTY
TO SOUTHWEST HARNEY COUNTY AND WILL GRADUALLY PUSH THROUGH THE REST
OF THE ZONES TONIGHT. PREFRONTAL PRECIP HAS BEEN LIGHT SO FAR WITH
LIGHT RAIN AT TIMES IN BAKER CITY AND BKE COUNTY SNOTEL SHOWING UP
TO 2 INCHES. SIMILARLY SNOW ACROSS THE WEST CENTRAL MTS AT MYL LEFT
0.06 LIQUED WITH LITTLE SNOW AT SNOTELS EXCEPT NEAR 2 INCHES IN
ADAMS COUNTY AT BEAR BASIN. LIGHTNING WAS DETECTED IN NE OREGON AND
ERN WASHINGTON WITH THE STRONGER THERMAL SUPPORT ALONG FRONT AS LATE
AT 7 PM BUT AFTERNOON INSTABILITY AND LTG HAS WANED SINCE. 700 MB
FLOW OF 40-30 KTS SATURDAY AFTERNOON WILL MIX WITH LGT SFC GRAD FOR
LOCALLY BREEZY AFTERNOON MAINLY EAST OF BOISE SATURDAY AFTERNOON.
WARMING TREND SUPPORTED BY NEW RUNS.
.PREVIOUS DISCUSSION...230 PM MST FRI MAR 5 2004 FOR THE SHORT
TERM...FOR SOUTHEAST OREGON AND SOUTHWEST IDAHO THROUGH MONDAY. A
WARM FRONT WAS CROSSING OUR AREA THIS AFTERNOON. A COLD FRONT WILL
CROSS TONIGHT. WELL AHEAD OF THE COLD FRONT... SNOW AND RAIN WILL
BE INCREASING LATE THIS AFTERNOON OVER OUR NORTH AND WESTERN ZONES
THEN SPREAD ACROSS THE AREA TONIGHT. OUR NORTHERN MOST ZONES FROM
THE BOISE MOUNTAINS NORTHWARD WILL SEE MODERATE TO LOCALLY HEAVY
SNOWS TONIGHT. WILL CONTINUE THE SNOW ADVISORY FOR THOSE ZONES.
SCATTERED SHOWERS WILL LINGER BEHIND THE FRONT SATURDAY MORNING.
DRIER NORTHWEST FLOW ALOFT WILL BRING A DECREASE IN SHOWER
ACTIVITY. SATURDAY NIGHT AN UPPER RIDGE WILL BE BUILDING FOR AN END
TO THE SHOWERS IN THE SOUTH. THE NORTH WILL CONTINUE TO SEE SNOW AND
RAIN SHOWERS INTO SUNDAY WITH WEAK WAVES MOVING OVER THE TOP OF THE
RIDGE. A DRY DAY IS ON TAP FOR MONDAY AS THE UPPER RIDGE TAKES
OVER. TEMPERATURES WILL BE CLOSE TO NORMAL ON SATURDAY THEN RISE TO
ABOUT 10 DEGREES ABOVE NORMAL ON SUN/MON.
.LONG TERM...TUESDAY THROUGH FRIDAY...THE LONG WAVE RIDGE CONTINUES
TO AMPLIFY AND SLOWLY PROGRESS EASTWARD ON TUESDAY FOR POTENTIALLY
THE WARMEST DAY OF THE YEAR SO FAR FOR MANY LOCATIONS. A NORTHERN
STREAM SHORT WAVE TROUGH...SPLIT OFF FROM A SOUTHERN STREAM CUT-OFF
LOW IN THE PACIFIC...RIDES OVER THE RIDGE EARLY WEDNESDAY BRINGING
CLOUD COVER AND A SLIGHT CHANCE OF PRECIP TO THE NORTHERN ZONES.
THIS FEATURE IS NOW AGREED UPON TODAY BY MOST OF THE MODELS HOWEVER
TIMING REMAINS AN ISSUE. A PACIFIC SURFACE HIGH TAPING A CANADIAN
AIRMASS MOVES OVER THE REGION DURING THE DAY WEDNESDAY BRINGING A
SLIGHT COOL DOWN FOR WEDNESDAY AND THURSDAY TEMPERATURES. ANOTHER
WAVE IN THE UPSTREAM TEAMS UP WITH THE CUT-OFF LOW IN THE PACIFIC
LATE IN THE PERIOD AND MOVES ACROSS THE CWA. MUCH DISAGREEMENT
TODAY CONCERNING THIS SYSTEM. I PREFER THE CHARACTERISTICS OF THE
12Z MRF WITH THIS TROUGH IN THAT THE SYSTEM WILL MOST LIKELY BE
SPLIT AS IT ENTERS THE COAST...HOWEVER I LIKE THE SLIGHTLY EARLIER
TIMING MORE IN LINE WITH THE ECMWF AND CANADIAN SUCH THAT THE WAVE
SHOULD AFFECT THE REGION EARLY TO MID-DAY FRIDAY. TEMPERATURES
REMAIN ABOVE NORMAL THROUGHOUT THE PERIOD ON THE AVERAGE OF 2 TO 6
DEGREES.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
.ID...SNOW ADVISORY 6 PM MST THIS EVENING TO 3 AM MST SATURDAY
MORNING ZONES 11 13.
.OR...SNOW ADVISORY 3 PM PST THIS AFTERNOON TO 11 PM PST TONIGHT
ZONE 62.
$$
SHORT TERM...TE
LONG TERM....RH
AREA FORECAST DISCUSSION
NWS SEATTLE WA
AFDSEW 910 PM PST FRI MAR 5 2004
.SYNOPSIS...THE STORM SYSTEM RESPONSIBLE FOR THE WINDY CONDITIONS
AND SNOW IN THE CASCADES HAS MOVED EAST. SHOWERS IN THE WAKE OF THE
SYSTEM WILL DIMINISH OVERNIGHT. A WEAKER SYSTEM WITH AN ASSOCIATED
WARM FRONT WILL BRING MORE PRECIPITATION TO THE REGION LATER
SATURDAY INTO SUNDAY.
&&
.DISCUSSION...SATELLITE IMAGERY AND WSR-88D SHOW NICE CLEARING OVER
THE PUGET SOUND AREA...THE RESULT OF GOOD DOWNSLOPE WINDS OFF THE
OLYMPICS. ACARS SOUNDINGS CONFIRM WESTERLY WINDS ALOFT WITH 850 MB
WINDS AROUND 30 KNOTS. TEMPERATURES DROPPING IN WIND SHELTERED
LOCATIONS WHILE WINDIER SPOTS LIKE SEA-TAC STILL IN THE LOWER 40S.
GRADIENTS ON THE DECREASE OVERNIGHT BUT STILL EXPECT ENOUGH WINDS TO
KEEP THE LOWS FROM FALLING MUCH FURTHER. STRONG FLOW THROUGH THE
STRAIT CONTINUES TONIGHT BUT THIS COMBINED WITH THE WINDS ALOFT HAVE
PUSHED CONVERGENCE INTO THE CASCADES. EVEN WITH THE CONVERGENCE
PRECIPITATION AMOUNTS IN THE CASCADES ARE RUNNING BELOW A TENTH OF
AN INCH AN HOUR PER AVALANCHE OBS. 850 MB WINDS WILL DIMINISH LATER
TONIGHT INTO SATURDAY MORNING AS WEAK UPPER LEVEL RIDGE MOVES INTO
THE AREA. WILL DOWNGRADE THE WINTER STORM WARNING IN THE CASCADES TO
A SNOW ADVISORY. NEXT SYSTEM...CURRENTLY NEAR 48N/140-150W...BEING
PUSHED ALONG AGAIN BY A STRONG JET...150 KNOTS PLUS ON THE AIREPS
FROM 00Z. GFS MODEL THE FASTEST OF THE 00Z MODEL RUNS BRINGING
PRECIPITATION BACK TO WESTERN WASHINGTON SATURDAY AFTERNOON AND THE
GFS HAS UNDERDONE THE JET CORE BY 30-40 KNOTS. WILL STAY WITH THE
CURRENT FORECAST VERSUS THE DRY ETA SOLUTION FOR SATURDAY AFTERNOON.
FRONT HANGS UP OVER WESTERN WASHINGTON DURING THE DAY ON SUNDAY.
OTHER THAN SOME FIRST PERIOD ADJUSTMENTS LITTLE CHANGE TO THE
FORECAST PACKAGE. FELTON
&&
.SEW...GALE WARNING CENTRAL AND EASTERN U.S. STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY COAST AND REST OF THE INLAND WATERS.
SNOW ADVISORY NORTH AND CENTRAL CASCADES.
.KATX...VCP21/CSR21.
&&
$$