215 FXUS66 KPQR 170310 AFDPQR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PORTLAND OR 900 PM PDT FRI MAY 16 2008 .SYNOPSIS...A STRONG HIGH PRESSURE ALOFT OVER SOUTHWEST WASHINGTON AND NORTHWEST OREGON BLASTED MANY HIGH TEMPERATURE RECORDS TODAY...REPORTS OF 100 DEGREES WERE NOT UNCOMMON ALL THE WAY TO THE COAST WITH SOME TEMPERATURES REPORTED ABOVE 100. ONE UNOFFICIAL REPORTING POINT AT SURF PINES NEAR THE NORTH OREGON COAST REPORTED 105 DEGREES THIS AFTERNOON...AND THE REMOTE AUTOMATED WEATHER SITE NEAR TILLAMOOK REPORTED 102. THE STRONG UPPER LEVEL HIGH PRESSURE RIDGE WILL BEGIN TO EASE EASTWARD TONIGHT THEN SINK SOUTH INTO CALIFORNIA SATURDAY AND SUNDAY. A SURFACE THERMAL TROUGH WILL CONTINUE TO WEAKEN AND SHIFT NORTH OFF THE WASHINGTON COAST TONIGHT AND EARLY SATURDAY THEN INLAND ON SATURDAY AND SUNDAY. A SHALLOW MARINE AIR MASS WILL DEVELOP ALONG THE COAST TONIGHT AND REMAIN ALONG THE COAST SATURDAY. THE MARINE AIR MASS WILL DEEPEN SATURDAY NIGHT AND SUNDAY AS ONSHORE FLOW INCREASES AND PUSHES INLAND THROUGH THE COASTAL GAPS SUNDAY. ONSHORE FLOW WILL CONTINUE MONDAY THEN THE NEXT FRONT WILL MOVE THROUGH AREA MONDAY NIGHT. THE ASSOCIATED UPPER TROUGH WILL MOVE ACROSS AREA TUESDAY. THE NEXT SYSTEM MOVES INTO AREA WEDNESDAY NIGHT AND THURSDAY. WILLSON && .SHORT TERM...TEMPERATURES HAVE BEGUN TO DECREASE THIS EVENING AFTER REACHING THE UPPER 90S TO 100 OR MORE AT PLACES ALL THE WAY TO THE COAST. TEMPERATURES WILL BEGIN TO DECREASE NOW AND WILL LET THE HEAT ADVISORY EXPIRE AT 8 PM PDT, THE SURFACE THERMAL TROUGH WILL CONTINUE TO WEAKEN AND LIFT NORTH TONIGHT TO OFF THE WASHINGTON COAST BY EARLY SATURDAY AS THE STRONG PACIFIC NORTHWEST UPPER HIGH TILTS EAST AND THE FLOW ALOFT TURNS MORE SOUTH AND SOUTHWEST. A SOUTHERLY SURGE OR WIND REVERSAL IS ALREADY UNDERWAY ALONG THE COAST AND DESPITE THE CURRENT CLEAR SKIES EXPECT FOG AND SHALLOW MARINE STRATUS TO DEVELOP AND SPREAD NORTH ALONG THE ENTIRE COAST LATER TONIGHT AND SATURDAY MORNING. THIS SOUTHERLY SURGE WILL BRING SIGNIFICANT COOLING TO THE COAST TONIGHT AND SATURDAY THAT WILL CONTINUE NEXT WEEK. THE MARINE LAYER ALONG THE COAST WILL CONTINUE TO DEEPEN SATURDAY AND SUNDAY AS THE UPPER HIGH THEN SINKS SOUTH AND THE THERMAL TROUGH MOVES EAST OF THE CASCADES. ONSHORE FLOW WILL DEVELOP INLAND ON SATURDAY AS THE MARINE AIR SEEPS INLAND AND EVEN BRINGS A LITTLE COOLING INLAND...WITH SOUTHWEST WINDS LIKELY FIRST NEAR EUGENE LATER TONIGHT AND SATURDAY...REACHING PORTLAND LAST. TEMPS INLAND SATURDAY SHOULD BE STILL QUITE WARM BUT GENERALLY IN THE 85 TO 90 RANGE EXCEPT CLOSER TO 80 NEAR EUGENE...THEN IN THE UPPER 70S TO NEAR 80 ON SUNDAY AS SOME LOW CLOUDS PUSH INTO THE COASTAL GAPS AND LOCALLY INTO THE VALLEYS SUNDAY MORNING. NOT A LOT CHANGE MONDAY EXCEPT A BIT MORE LOW CLOUDS INLAND IN THE MORNING AND A BIT COOLER TEMPS...MORE DOWN IN THE 70S. THE NEXT FRONT WILL BE APPROACHING THE NORTHWEST LATE MONDAY BUT HELD OFF ON RAIN UNTIL MONDAY NIGHT...BUT THIS WILL BEAR WATCHING. WILLSON .LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS... MID RANGE MODELS IN RELATIVE AGREEMENT CONTINUING ONSHORE FLOW AND MILD WEATHER THROUGH THE EXTENDED PERIOD. A SHORT WAVE FEATURE WILL ADVANCE OVER THE RIDGE MON NIGHT INTO TUE... BRINGING LIGHT PRECIPITATION TO THE AREA MON NIGHT AND INTO TUE MORNING. SHOWERS WILL CONTINUE IN ONSHORE FLOW AS THE SHORT WAVE CONTINUES TO DIG EAST OF THE FORECAST AREA TUE INTO TUE NIGHT. AS THE RIDGE TRIES TO BUILD BACK IN BEHIND THIS FEATURE...ONSHORE FLOW WILL CONTINUE AND BRING CLOSER TO NORMAL TEMPERATURES BUT VERY LITTLE PRECIPITATION FOR THE REMAINDER OF THE WEEK. BROWN && .AVIATION...LIMITED VFR TIME ON THE COAST WITH POSSIBLE FOG/LOW STRATUS FORMATION EARLY SAT MORNING IN WAKE OF HIGH TEMPERATURES. WEAK ONSHORE FLOW ALONG THE COAST AS OF EARLY THIS EVENING. MODELS NOT SHOWING ANY MOISTURE MOVING INLAND WITH A TRUE MARINE PUSH UNTIL SAT MIDDAY ...ALTHOUGH LIKELY THAT PATCHY STRATUS/FOG WILL FORM IN-SITU OVERNIGHT. LOOK FOR VFR CONDITIONS TO DETERIORATE BY 10Z SAT AM CENTRAL COAST...TO 14Z NORTH OR AND SOUTH WA COAST. KPDX AND APPROACHES...VFR CONDITIONS EXPECTED TO PERSIST THROUGH SAT EVENING. && .MARINE...THE THERMAL TROUGH WILL CONTINUE TO BUILD NORTH ALONG THE COAST TONIGHT BEFORE PUSHING INLAND SAT. SEAS BELOW 10 FT THROUGH MON AFTERNOON. && .PQR WATCHES/WARNINGS/ADVISORIES... WA/OR...SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR EARLY SATURDAY MORNING. && .PRELIMINARY POINT POPS (PROBABILITY OF MEASURABLE PRECIPITATION) AST 0----1 PDX 000001 SLE 00000- EUG 00000- $$ MORE WEATHER INFORMATION ONLINE AT... Http://weather.gov/portland THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY REFERRED TO AS THE FORECAST AREA.