Severe Thunderstorm Warning 1, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
250 PM PDT WED MAY 17 2006

.DISCUSSION...INCREASED INSTABILITY COMPARED WITH YESTERDAY IS
INDICATED BY EARLIER CUMULUS DEVELOPMENT THIS AFTERNOON...INCLUDING
A WEAK THUNDERSTORM NEAR CHEMULT. EXPECT KLAMATH AND LAKE COUNTIES
TO BE THE FOCUS FOR ISOLATED LATE AFTERNOON AND EVENING
THUNDERSTORMS WITH DEVELOPMENT ALSO OVER THE CASCADES AND SISKIYOUS
AND INTO SISKIYOU AND MODOC COUNTIES. AFTER RECORD OR NEAR RECORD
WARMTH THIS AFTERNOON...A LITTLE COOLER THURSDAY BUT CONTINUED
UNSTABLE WITH SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS
FROM THE CASCADES EASTWARD.

THE SIMPLE SUMMER-LIKE WEATHER PATTERN OF THE PAST WEEK IS BEGINNING
TO TRANSITION TO A MORE COMPLEX SPRING-LIKE PATTERN. THIS COMPLEXITY
IS ILLUSTRATED BY THE RATHER DRASTIC RUN-TO-RUN CHANGES FOR FRIDAY
THROUGH THE WEEKEND INDICATED BY THE 12Z GFS. CONFIDENCE IS NOT HIGH
IN THE DETAILS AS OTHER MODELS DO NOT SUPPORT THE EXTENT OF CHANGE
FOR FRIDAY OF A MUCH COOLER...STRONGER/MORE MOIST RESULT WITH FASTER
MOVEMENT OF THE OFFSHORE UPPER LOW. I HAVE LEANED TOWARD THE ECMWF
WHICH MAINTAINS A WEAKER/SLOWER SPLIT FLOW. BROAD BRUSH HAS BEEN
UTILIZED WITH A SLIGHT CHANCE TO CHANCE OF SHOWERS FROM FRIDAY
THROUGH WEDNESDAY AND TEMPERATURES NEAR TO SLIGHTLY BELOW NORMAL.

&&

.AVIATION...GENERALLY VFR CONDITIONS TONIGHT EXCEPT ISOLATED TO
WIDELY SCATTERED THUNDERSTORMS FROM THE CASCADES EASTWARD THIS
AFTERNOON AND EVENING AND IFR/MVFR CEILINGS IN STRATUS AND PATCHY
FOG ALONG THE COAST INTO THE COQUILLE BASIN AND WESTERN DOUGLAS
COUNTY.

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...SMALL CRAFT ADVISORY CAPE BLANCO-CA BORDER 20-60 NM.
CA...SMALL CRAFT ADVISORY OR BORDER-PT ST GEORGE 20-60 NM.

&&

DW