000 
FXUS66 KPQR 210335
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
835 PM PDT WED APR 20 2005

.SYNOPSIS...UPPER LEVEL LOW OVER SOUTHERN IDAHO WILL MOVE SLOWLY
WESTWARD THROUGH FRIDAY. THE LOW WILL MOVE INTO WESTERN OREGON BY
FRIDAY MORNING THEN MOVE OFFSHORE FRIDAY NIGHT. THIS WILL BRING
INCREASED CHANCES OF CONVECTION THROUGH FRIDAY AND SATURDAY. ONSHORE
FLOW THAT WILL BRING MORE LOW CLOUDS TONIGHT AND THURSDAY
MORNING...WILL WEAKEN AS THE LOW MOVES OVERHEAD THEN OFFSHORE BY
SATURDAY. AS THE LOW INTERACTS WITH ANOTHER LOW OFF CALIFORNIA AND
BEGINS TO MOVE ONSHORE LATER SATURDAY INTO SUNDAY EXPECT MORE
CONVECTION TO DEVELOP...WITH A POSSIBLE SOUTHWEST MARINE PUSH
SATURDAY NIGHT.
&&

.SHORT TERM...THE UPPER LOW WE HAVE BEEN TRACKING THE LAST COUPLE OF
DAYS IS NOW IN SOUTHERN IDAHO...WITH SOME MOISTURE HAVING SPREAD WEST
INTO SOUTHWEST WASHINGTON AND NORTHWEST OREGON THIS EVENING. THE
SALEM RAOB CONFIRMS THE MODEL SOUNDING FORECAST OF A LITTLE WARMING
ALOFT THAT HAS REDUCED THE INSTABILITY THREAT THIS EVENING IN OUR
AREA. ECHOES ON THE NATIONAL WEATHER SERVICE DOPPLER RADAR HAVE BEEN
LIGHT AND PROBABLY NOT REACHING THE GROUND. WILL KEEP A FEW SPRINKLES
NEAR THE CASCADES THROUGH THE EVENING. ALSO HAVE SOLID LOW CLOUDS
ALONG THE COAST THAT WILL SPREAD INLAND OVERNIGHT...AT LEAST AS SOLID
AS THIS MORNING IF NOT MORE SOLID IN CONTINUED ONSHORE FLOW.

THE LOW OVER SOUTHERN IDAHO IS FORECAST TO MOVE BACK WEST AND
APPROACH OUR AREA LATER THURSDAY. THIS SHOULD STEEPEN LAPSE RATES AND
GIVE US A BETTER CHANCE OF CONVECTION ON THE CASCADES LATE THURSDAY
AFTERNOON AND EVENING...AND GIVEN THE ASSOCIATED UPPER LEVEL FLOW
POSSIBLY SPREAD THE CHANCE OF CONVECTION WEST OF THE CASCADES IN THE
EVENING. THE MOVEMENT OF THE LOW MAY DISRUPT THE MARINE LAYER SOME
ESPECIALLY INLAND ON FRIDAY MORNING. WITH THE LOW NEARLY OVERHEAD
FRIDAY...EXPECT MORE CONVECTION OVER THE MOUNTAINS. WILL NEED TO
WATCH FOR THE VALLEYS AS WELL. ON FRIDAY THE THERMAL TROUGH IS
OVERHEAD AND MAY SEE TEMPS INLAND TOP 70.

THE LOW CONTINUES WEST AND OFFSHORE SATURDAY. THIS SHOULD REDUCE THE
ONSHORE FLOW AND LOW CLOUDS FOR SATURDAY...BUT INCREASE THE
CONVECTION CHANCES AS THE UPPER FLOW TURNS SOUTHERLY AS THE LOW NEAR
OUR COAST INTERACTS WITH A LOW OFF CALIFORNIA...THEN MOVES ONSHORE
LATER SATURDAY INTO SUNDAY. STILL LOOKS PRETTY WARM SATURDAY.
POSSIBLE SOUTHWEST MARINE PUSH SATURDAY NIGHT MAY INFLUENCE THE
OUTCOME OF THE EXPECTED CONVECTION. WILL FINE TUNE LATER. TOLLESON

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
ONSHORE FLOW OVER AREA FOR SUN WILL BRING MORE CLOUDS AND COOLER
TEMPS.  HAVE LEFT LINGERING THREAT OF SHOWERS ON CASCADES SUN BUT
MAIN INSTABILITY E OF AREA WITH THERMAL TROUGH OVER ERN ORE. NO
CHANGES IN FORECAST FOR MON THROUGH WED THOUGH ONSHORE FLOW MAY KEEP
TEMPS A LITTLE COOLER MON. KOSOVITZ
&&

.PRELIMINARY POINT POPS
AST 111111  PDX 112112  SLE 112112  EUG 112112
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
.OR/WA...NONE.

$$

MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND