Severe Thunderstorm Warning 8, NWS Seattle, WA

000 
WWUS56 KSEW 031746
SVSSEW

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SEATTLE WA
1044 AM PDT THU JUL 3 2008

WAC033-061-031754-
/O.EXP.KSEW.SV.W.0008.000000T0000Z-080703T1745Z/
KING WA-SNOHOMISH WA-
1044 AM PDT THU JUL 3 2008

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN SNOHOMISH AND
WEST CENTRAL KING COUNTIES EXPIRES AT 1045 AM PDT...

A STRONG THUNDERSTORM WAS LOCATED BETWEEN WOODINVILLE AND DUVALL AT 
1043 AM. SPOTTER REPORTS HAVE INDICATED HAIL UP TO ONE-HALF INCH IN 
DIAMETER. THIS STORM WILL CONTINUE MOVING NORTH-NORTHEAST AROUND 30 
MPH TOWARD MONROE AROUND 1100 AM. GIVEN RECENT SPOTTER REPORTS BELOW 
SEVERE CRITERIA...THE SEVERE THUNDERSTORM WARNING IS BEING ALLOWED 
TO EXPIRE. STILL...PEOPLE IN THE PATH OF THIS STRONG STORM SHOULD 
MOVE INDOORS.

LAT...LON 4793 12222 4790 12189 4741 12202 4743 12229
TIME...MOT...LOC 1744Z 188DEG 35KT 4781 12207

$$

HANER

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
940 AM PDT THU JUL 3 2008

.SYNOPSIS...A MOIST AND UNSTABLE AIR MASS WILL PERSIST TODAY FOR
SCATTERED SHOWERS OR THUNDERSTORMS AS A LOW PRESSURE SYSTEM OFFSHORE
MAINTAINS SOUTHERLY FLOW ALOFT. THE FLOW WILL BECOME MORE SOUTHWEST
TONIGHT AS THE OFFSHORE LOW APPROACHES. EXPECT THE SYSTEM TO MOVE
ACROSS THE REGION ON JULY FOURTH FOR A CONTINUED RISK OF SHOWERS.
THE TAIL END OF ANOTHER TROUGH WILL BRUSH WESTERN WASHINGTON ON
SATURDAY...THEN LOOK FOR A TREND TOWARD DRIER WEATHER ON SUNDAY AS
HIGHER PRESSURE BUILDS OVER THE PACIFIC NORTHWEST.

&&

.SHORT TERM...UPDATED AVIATION SECTION. AN UPPER LEVEL CUTOFF LOW
CONTINUES TO SPIN OVER THE ERN PAC NEAR 47N 132W WITHIN A LONGWAVE
TROUGH. DUE SOUTHERLY FLOW ALOFT BROUGHT UP LOTS OF MID-HIGH LEVEL
MOISTURE YESTERDAY AFTERNOON WHICH MIXED WITH THE UNSTABLE AIR
ALREADY IN PLACE TO PRODUCE LAST NIGHTS PROLIFIC LIGHTNING. LOOKING
UPSTREAM...THERE ARE TWO MORE EASILY IDENTIFIABLE SHORTWAVES
EJECTING FROM THE ERN PAC LONGWAVE TROUGH. THE FIRST SHOULD IMPACT
THE FORECAST AREA LATER THIS AFTERNOON...THEN THE SECOND SHORTWAVE
WILL IMPACT US OVERNIGHT TONIGHT. UPPER FLOW THIS AFTERNOON WILL
STILL BE SOUTHERLY...SO MORE LIGHTNING IS EXPECTED OVER MUCH OF WRN
WA. BY THE OVERNIGHT HOURS...UPPER FLOW WILL BECOME MORE
SOUTHWESTERLY AND PUSH ANY REMAINING THUNDER INTO OR EAST OF THE
CASCADES.

FOR FRIDAY JULY 4...THE ERN PAC LONGWAVE TROUGH STARTS TO DE-AMPLIFY
AND WEAKEN AS IT MOVES INTO THE PAC NW. STILL...THE PRESENCE OF THE
TROUGH AXIS WILL CAUSE FRIDAY TO BE A CLOUDY...COOL AND SOMEWHAT
SHOWERY DAY. BY FRIDAY EVENING...THE TROUGH AXIS SHOULD LEAVE US
BEHIND AS IT MOVES INTO ERN WA...FINALLY ALLOWING FOR DIMINISHED
SHOWERY ACTIVITY AND A FEW BREAKS IN THE CLOUD COVER...JUST IN TIME
FOR EVENING ACTIVITIES.

BY SATURDAY...WE WILL HAVE RETURNED TO MORE OF A WESTERLY ZONAL FLOW
PATTERN. A SHARP UPPER TROUGH IS EXPECTED TO PASS EAST IN THE ZONAL
FLOW ACROSS B.C. WITH THE TAIL END OF THE TROUGH AFFECTING WRN WA.
WOULD EXPECT THIS TO ENHANCE CLOUDS AND SHOWER ACTIVITY ON
SATURDAY...BUT THE AIR MASS WILL HAVE STABILIZED ENOUGH FOR
LIGHTNING NOT TO BE A CONCERN.      HANER

.LONG TERM...FROM PREVIOUS DISCUSSION...THIS PERIOD WILL BE
DOMINATED BY A WEAK UPPER RIDGE OVER THE PAC NW AND CONTINUED
ONSHORE FLOW. HAVE REMOVED THE CHANCE OF SHOWERS FROM THE FORECAST
FOR SUNDAY SINCE IT NOW APPEARS THAT IT WILL BE DRY.
OTHERWISE...ANTICIPATE NEAR OR SLIGHTLY ABOVE NORMAL DAYTIME TEMPS
ALONG WITH VARYING AMOUNTS OF NIGHT/MORNING STRATUS.

&&

.AVIATION...940 AM...THE LOW STRATUS IS STILL MAINLY COAST STRAIT
AND AREAS OVER THE INLAND WATERS...BUT IS ALSO WORKING INTO SEA-PAE
AT TIMES. MIX THAT UP WITH THE SHOWERS AND THUNDERSTORMS DROPPING
RAIN INTO THE SHALLOW COOL STABLE LAYER AND IT WILL BE A LOUSY DAY
WITH FREQUENT AMENDMENTS TO THE TAFS. 19

KSEA...AT 940 AM THERE WERE 2 OR 3 THUNDERSTORMS EMBEDDED IN A LINE
OF SHOWERS THAT STRETCHES THRU SNOHOMISH COUNTY SOUTH THRU KING
COUNTY AND TO A CELL 10 MILES EAST OF TACOMA. THESE TSTMS SHOULD
MOVE NORTH OUT OF THE METRO AREA IN AN HOUR OR TWO. THE STRONGEST
LOOKING CELL IS THE ONE JUST CROSSING INTO KING COUNTY FROM THE
SOUTH AND SHOULD PASS JUST EAST OF SEA TAC 17Z-1730Z. 19

&&

.MARINE...GRADIENTS ARE QUITE LIGHT...A LITTLE WESTERLY PUSH IN THE
STRAIT THIS EVENING. MM5NAM HAS 15KTS...IT WILL PROBABLY BE AROUND
20KTS FOR SEVERAL HOURS.
&&

.SEW WATCHES/WARNINGS/ADVISORIES...
PZ...SMALL CRAFT ADVISORY CENTRAL STRAIT OF JUAN DE FUCA AND EAST
     ENTRANCE.
WA...NONE.

WEATHER.GOV/SEATTLE