000
FXUS66 KMFR 202132
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
232 PM PDT MON MAY 20 2013

.DISCUSSION...MODELS CONTINUE ON TRACK WITH THE APPROACHING COLD
AIR MASS APPROACHING THE REGION WITH THE UPCOMING SYSTEM. THE
SYSTEM MOVES INTO THE AREA TUESDAY WITH MODELS STILL INDICATING
850 TEMPS IN THE -4C RANGE AND 500 MB TEMPS A LITTLE WARMER THAN
YESTERDAYS RUNS WERE SHOWING. 500 MB TEMPS ARE IN THE -18 TO -27 C
RANGE COMPARED TO THE -25 TO -35C RANGE THEY SHOWED YESTERDAY.
WITH THIS IN MIND HAVE CUT BACK THE AREA OF THUNDERSTORMS TO THE
COOLER POOL AREAS ALONG THE NORTHERN COAST. SNOW LEVELS CONTINUE
TO INDICATE AROUND 2500 FEET AND WITH STRONG LOW LEVEL LAPSE RATES
THIS COULD DROP TO AROUND 2000 FT BRIEFLY. HOWEVER...WITH
SEASONABLY WARM SURFACE TEMPERATURES AM NOT EXPECTING THIS TO LAST
LONG ON THE GROUND. ONSHORE FLOW CONTINUES SHOWERS WITH THE COLD
AIR MASS THROUGH THURSDAY. AS THE UPPER LOW SLOWLY MOVES EAST
INCREASED SOUTHWESTERLY FLOW ON THURSDAY BRINGS WARMER LOW LEVEL
TEMPS TO THE FAR EAST SIDE AND THUNDERSTORMS ARE POSSIBLE IN THIS
LOCATION. THE UPPER LEVEL TROUGH REMAINS ROUGHLY IN PLACE WITH
ANOTHER CLOSED LOW MOVING INTO THE REGION TOWARDS THE
WEEKEND....BUT THE AIR MASS ACCOMPANYING IT WILL NOT BE NEARLY AS
COLD RESULTING IN A SHOWERY BUT NEAR NORMAL TEMPERATURES HOLIDAY
WEEKEND.


&&

.AVIATION...MOSTLY CLEAR SKIES WILL PREVAIL THROUGH EARLY THIS EVENING.
TONIGHT CLOUD COVER WILL INCREASE ALONG THE COAST MID TO LATE
EVENING, AND THEN EAST TO THE CASCADES BY ABOUT SUNRISE. VFR
CONDITIONS ARE LIKELY TO PREVAIL THROUGH LATE EVENING. THEREAFTER
EXPECT AREAS OF MVFR TO DEVELOP ALONG THE COAST AND MOUNTAIN
OBSCURATIONS TO INCREASE TO TOTAL BY SUNRISE ON THE COAST MOUNTAIN
RANGE. TUESDAY MORNING MVFR CEILINGS WILL BECOME WIDESPREAD ALONG
AND NEAR THE COAST RANGE AND IN THE UMPQUA BASIN, AND TERRAIN
OBSCURATIONS WILL BEGIN AND THEN INCREASE ACROSS THE UMPQUA
DIVIDE, SISKIYOUS, AND CASCADES THROUGH THE MORNING. BTL


&&

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

CA...NONE.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS UNTIL 11 PM PDT THIS EVENING FOR
     PZZ356.
     SMALL CRAFT ADVISORY FOR WINDS FROM 11 AM TO 8 PM PDT TUESDAY
     FOR PZZ350-356.
     HAZARDOUS SEAS WARNING FROM 8 AM TUESDAY TO 8 PM PDT WEDNESDAY
     FOR PZZ350-356-370-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 11 PM PDT THIS
     EVENING FOR PZZ356.
     SMALL CRAFT ADVISORY FOR WINDS UNTIL 8 PM PDT THIS EVENING FOR
     PZZ350-370.
     SMALL CRAFT ADVISORY FOR WINDS FROM 8 AM TUESDAY TO 5 AM PDT
     THURSDAY FOR PZZ370-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 PM PDT THIS
     EVENING FOR PZZ350-370.
     GALE WARNING UNTIL 8 PM PDT THIS EVENING FOR PZZ376.
     HAZARDOUS SEAS WARNING UNTIL 8 PM PDT THIS EVENING FOR PZZ376.

$$

SVEN