Tornado in Oregon, June 18, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
250 PM PDT TUE JUN 18 2013

.SHORT TERM...THE UPPER LEVEL LOW PRESSURE OFF NW OREGON COAST
WILL CONTINUE TO SPEND A SERIES OF WEAK DISTURBANCE INLAND TONIGHT
AND WEDNESDAY. COOL AND UNSTABLE AIR MASS WILL HELP TO
DESTABILIZE THE ATMOSPHERE WITH INTERMITTENT LIGHT RAIN SHOWERS.
THUNDERSTORMS ARE POSSIBLE THIS EVENING..MAINLY FROM THE CASCADES
EAST AND SOUTH INTO SISKIYOU AND MODOC COUNTIES. INSTABILITY
INDICES ARE NOT VERY HIGH AND LIGHTNING STRIKES ARE EXPECTED TO BE
ISOLATED IN COVERAGE. EXPECT COOLER THAN NORMAL TEMPERATURES ON
WEDNESDAY AS MORE COOLER AIR MOVES INTO THE AREA ALONG WITH
POTENTIAL FOR SHOWERS. ONLY NORTHERN KLAMATH AND LAKE COUNTIES
WILL HAVE ENOUGH INSTABILITY FOR LIGHTNING STRIKES. SOME CLEARING
ON WEDNESDAY NIGHT COULD BRING TEMPERATURES IN THE KLAMATH AND
TULELAKE BASINS DOWN CLOSE TO FROST POINTS.

THE LOW PRESSURE IS EXPECTED TO MOVE INTO NE OREGON AND EASTERN
WASHINGTON ON THURSDAY BUT LINGERS IN THAT GENERAL AREA THROUGH
FRIDAY. WE WILL SEE SOME WARMING AND DRYING THURSDAY AND FRIDAY
THE COLD AIR MOVES EAST. HOWEVER THERE IS A CONCERN THAT MOISTURE
ROTATING AROUND THE LOW PRESSURE COULD LEAD TO UPSLOPE SHOWERS IN
THE FAR EASTERN DOUGLAS COUNTY AND NORTHERN KLAMATH AND LAKE
COUNTIES THROUGH FRIDAY WHEREAS THE CHANCE FOR THE REST OF OUR
FORECAST AREA SHOULD BE OVER.

.LONG TERM...EXPECT BRIEF RIDGING ON SATURDAY WITH HIGHS WARMING
TO NORMAL...POSSIBLY INTO SUNDAY. WHILE BOTH LONG RANGE MODELS
HINT THAT ANOTHER LOW PRESSURE MOVE INLAND...THEY ARE BEGINNING TO
DIVERGE A BIT FROM SUNDAY INTO EARLY NEXT WEEK. THE ECMWF IS MORE
AGGRESSIVE WITH A FULL FLEDGED COLD FRONT INLAND WHEREAS THE GFS
HAS A WEAKER TROUGH MOVING THROUGH. THIS WILL AFFECT FORECAST
HIGHS NEXT WEEK. DECIDED TO STAY CLOSER TO THE GFS ON TEMPERATURES
KEEPING HIGHS CLOSE TO BUT JUST BELOW SEASONAL NORMS FROM SUNDAY
INTO NEXT WEEK. ALSO INTRODUCED PRECIPITATION TO THE EXTENDED
FORECAST. /FB

&&

.AVIATION...AN UPPER LOW WILL MOVE OVER THE AREA TONIGHT INTO
WEDNESDAY. THIS WILL RESULT IN SHOWERS, MOST NUMEROUS IN OREGON.
THERE CAN BE ISOLATED LIGHTNING TOO, ESPECIALLY OVER INTERIOR
OREGON THIS EVENING, THEN AGAIN OVER THE EAST SIDE WEDNESDAY
AFTERNOON. GUSTY WINDS IN THE ROGUE VALLEY AND OVER THE EAST SIDE
THIS EVENING WILL DIMINISH OVERNIGHT. CIGS WILL REMAIN MOSTLY A
MIX OF VFR AND MVFR, WITH THE LOWEST CIGS IN THE VICINITY OF
SHOWERS. AREAS OF IFR WILL PERSIST AT THE CURRY COAST. SPILDE

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.

CA...NONE.

PACIFIC COASTAL WATERS...NONE.

FJB/FJB/MAS