AREA FORECAST DISCUSSION
NWS SEATTLE WA
AFDSEW 855 AM PDT FRI JUL 9 1999
.OVERVIEW...THE LONG WAVE RIDGE THAT HAS BEEN WELL TO THE EAST OF THE
AREA FOR THE PAST FEW WEEKS HAS RETROGRADED WWD TO 110W. THIS IS
GIVING HIGH HEIGHTS AND OFFSHORE FLOW TO THE PACIFIC NW. AT 15Z A
WEAK THERMAL TROUGH WAS POSITIONED ALONG THE WA COAST WITH A SHALLOW
MARINE SURGE WORKING ITS WAY NWD ALONG THE CENTRAL OREGON COAST. 12Z
MODELS ARE CONSISTENT WITH PREVIOUS RUNS IN PROGRESSING A SHORT WAVE
H5 RIDGE AND ITS ASSOCIATED SURFACE THERMAL TROUGH EWD FROM WRN WA
ACROSS THE CASCADES THIS AFTERNOON AS A WEAK SHORTWAVE TROUGH NOW
CENTERED 45N/138W ROTATES NEWD ACROSS THE STATE TONIGHT AND SAT. THIS
SHOULD ALLOW SHALLOW MARINE AIR TO PENETRATE THE WRN WA INTERIOR
TONIGHT AND SAT FOR SOME COOLING. 12Z MODELS ARE WEAKER WITH THE
STRENGTH OF THE MARINE INTRUSION THAN THE CORRESPONDING 00Z
SOLUTIONS.
.SHORT TERM...PRESSURE GRADIENTS AND TEMPERATURES ALOFT BASED ON
MOUNTAIN OBSERVATIONS... KUIL SOUNDING...KATX PROFILER...AND ACARS
SOUNDINGS FROM KSEA SUGGEST MAX TEMP AT KSEA OF 86 TODAY SO WILL
ADJUST FIRST PERIOD TEMPS UP 2-3 DEG FROM MIDNIGHT PACKAGE. SATELLITE
IMAGERY SUGGEST THAT 12Z MODELS INITIALIZE SHORT WAVE NEARING 135W A
BIT WEAK...SO WILL MAINTAIN FORECAST OF MORNING CLOUDS...DRIZZLE
COAST AND MID-UPPER 70S IN INTERIOR SAT FOR 6-10 DEG COOLING. AFTER
PASSING SHORT WAVE TROUGH SAT...RIDGING AND HIGH HEIGHTS ALLOW
REBOUND OF TEMPERATURES SUN.
.EXTENDED...LONG WAVE ANALYSIS SHOWS CONTINUED RETROGRESSION OF THE
LONG WAVE RIDGE FROM THE WEST COAST MON-TUE TIME FRAME TO 135-140W BY
WED. LOOKS LIKE A PERIOD OF WARM TO NEAR HOT TEMPERATURES EARLY NEXT
WEEK FOLLOWED BY A PUSH LATE TUE OR WED. CURRENT EXTENDED IN THE BALL
PARK.
ALBRECHT
UIL 011 SEA 000 OLM 000
.KATX...VCP32/CSR32...OPERATIONAL.
.SEW...SMALL CRAFT ADVISORY STRAIT OF JUAN DE FUCA.