Freeze Warning 23, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
321 AM PDT MON OCT 31 2011

.DISCUSSION...A WEAK COLD FRONT WILL MOVE THROUGH THE AREA THIS
MORNING. UPSLOPE NORTH TO NORTHWEST FLOW IS BEHIND THE FRONT
RESULTING IN LOW CLOUDS AND PATCHY AREAS OF DRIZZLE MAINLY ALONG THE
WEST FACING SLOPES OF THE CASCADES AND NORTH SLOPES OF THE SISKIYOUS
FOR A FEW HOURS EARLY THIS MORNING. COOLER AND DRIER AIR MASS MOVES
OVERHEAD THIS AFTERNOON WITH OFFSHORE FLOW DEVELOPING RESULTING IN
DECREASING CLOUD COVER. HIGH PRESSURE BUILDS EAST OF THE CASCADES
TONIGHT WITH MOSTLY CLEAR SKIES OVER MOST AREAS. TEMPERATURES WILL
COOL DOWN QUICKLY IN THE EVENING...SO DRESS THE KIDS WARM FOR THE
TRICK AND TREATING.

DRY WEATHER CONTINUES TUESDAY AND MOST OF WEDNESDAY WITH COLD
TEMPERATURES IN THE MORNING AND COOL AFTERNOON. TEMPERATURES TUESDAY
NIGHT INTO EARLY WEDNESDAY ARE LIKELY TO DROP NEAR FREEZING IN THE
UMPQUA BASIN AND IN A FEW VALLEY LOCATIONS IN COOS COUNTY.SKIES
REMAIN MOSTLY CLEAR THROUGH WEDNESDAY MORNING...THEN HIGH AND MID
CLOUDS INCREASE FROM WEST TO EAST IN THE AFTERNOON IN ADVANCE OF A
STRONG COLD FRONT.

THE MODELS ARE IN FAIRLY GOOD AGREEMENT IN BRINGING A STRONG COLD
FRONT TO THE OREGON COAST LATE WEDNESDAY AFTERNOON. THE LATEST GFS
AND
NAM HAVE SLOWED THE TIMING OF THE FRONT UNTIL WEDNESDAY EVENING. THE
EC AND CANADIAN REMAIN SLIGHTLY FASTER. SO DECIDED TO PLAY THE
MIDDLE GROUND AND ADJUST POPS DOWN FOR THE INLAND AREAS...BUT KEPT
THEM ABOUT THE SAME FOR THE COAST...SPECIFICALLY NORTH OF CAPE
BLANCO.

BIG CHANGES ARE AHEAD STARTING WEDNESDAY NIGHT. THE FRONT MOVES
INLAND WEDNESDAY EVENING THROUGH NIGHT AND IS VERY LIKELY TO BRING
OUR FIRST SIGNIFICANT PRECIPITATION EVENT TO THE COAST RANGE AND
CASCADES SINCE EARLY OCTOBER. A COOL AIR MASS FOLLOWS RESULTING IN
SNOW LEVELS LOWERING AROUND 4000 TO 4500 FEET IN OREGON AND 5000 TO
5500 FEET IN NORTHERN CAL. SO IT'S A GOOD BET THE CASCADES AND
NORTHERN LAKE AND KLAMATH COUNTY SEE RAIN CHANGING OVER TO WET SNOW.
THE SUMMITS ALONG HIGHWAY 140 AND STATE HIGHWAY 66 COULD SEE
ACCUMULATING SNOW BY DAYBREAK THURSDAY. SO BE PREPARED FOR
WINTER TRAVEL IF TRAVELING OVER THESE ROADS.

MEANWHILE...WINDS WILL INCREASE ALONG AND EAST OF THE CASCADES
WEDNESDAY NIGHT INTO THURSDAY MORNING WITH 700 MB WINDS PROJECTED TO
BE BETWEEN 40 AND 50 KTS. NOT OUT OF THE QUESTION THE HIGHER TERRAIN
COULD GET CLOSE TO HIGH WIND CRITERIA.

DEEP UPPER TROUGH REMAINS OVER THE AREA THURSDAY AND FRIDAY WITH
RAIN AND SNOW SHOWERS EXPECTED TO PERSIST. SNOW LEVELS THURSDAY WILL
BE AROUND 3500 FEET...3000 FEET THURSDAY NIGHT AND 3500 FEET
FRIDAY.

THE DEEP UPPER TROUGH SHIFTS EAST OF THE CWA SATURDAY AND WE'LL GET
A BREAK IN THE WEATHER...THEN ANOTHER UPPER TROUGH MOVES INTO THE
REGION SATURDAY NIGHT BRINGING ANOTHER ROUND OF PRECIPITATION.

&&

.AVIATION...A COLD FRONT WILL PROGRESS OVER THE EAST SIDE
THIS MORNING. IFR CEILINGS WILL LIKELY DROPPING TO IFR AND LIFR
EARLY THIS MORNING BEHIND THE FRONT. DEW POINTS IN THE 50S SUPPORT
AT LEAST A BRIEF PERIOD OF WIDESPREAD IFR CEILINGS OVER THE WEST
SIDE MONDAY MORNING. ON THE EAST SIDE...VFR CONDITIONS WILL
CONTINUE...BUT THERE IS A CHANCE FOR LIFR CONDITIONS TO DEVELOP FOR
A FEW HOURS WITH PATCHY FREEZING FOG AFFECTING KLMT. MOUNTAIN
OBSCURATION WILL IMPACT TERRAIN FROM THE CASCADES WESTWARD THROUGH
MID MORNING. MOUNTAIN OBSCURATION SHOULD DIMINISH EVERYWHERE BY
THIS AFTERNOON WITH A MUCH DRIER AIR MASS FILTERING IN.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...FROST ADVISORY FROM 3 AM TO 9 AM PDT TUESDAY FOR ORZ023.
     FREEZE WARNING FROM 3 AM TO 9 AM PDT TUESDAY FOR ORZ023.
     FREEZE WATCH FROM LATE TUESDAY NIGHT THROUGH WEDNESDAY MORNING
     FOR ORZ023.

CA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 2 PM THIS AFTERNOON TO 11 AM
     PDT TUESDAY FOR PZZ350-356-370.
     HAZARDOUS SEAS WARNING FROM 2 PM THIS AFTERNOON TO 11 AM PDT
     TUESDAY FOR PZZ350-356-370.
     SMALL CRAFT ADVISORY FOR WINDS UNTIL 2 PM PDT THIS AFTERNOON FOR
     PZZ376.
     HAZARDOUS SEAS WARNING FROM 2 PM THIS AFTERNOON TO 11 PM PDT
     TUESDAY FOR PZZ376.
     GALE WARNING FROM 2 PM THIS AFTERNOON TO 11 AM PDT TUESDAY FOR
     PZZ376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 2 PM PDT THIS
     AFTERNOON FOR PZZ376.

PETRUCELLI