Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 021601
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
901 AM PDT WED SEP 2 2015

.DISCUSSION...A MOIST WEST TO SOUTHWEST FLOW ALOFT WILL REMAIN
OVER THE AREA TODAY. A WEAK FRONT HAS MOVED THROUGH THE AREA
BRINGING VERY LIGHT, BUT MEASURABLE RAINFALL MAINLY NORTH OF THE
UMPQUA DIVIDE, COOS, CURRY, WESTERN JOSEPHINE COUNTY AND NORTHERN
CASCADES FROM CRATER LAKE NORTH. ONSHORE FLOW WILL CONTINUE
THROUGH THE AFTERNOON AS THE UPPER LOW LOCATED NEAR VANCOUVER
ISLAND WILL MOVE SOUTH AND 500MB HEIGHT LOWER THIS AFTERNOON.
STILL COULD NOT RULE OUT A FEW SPRINKLES OR LIGHT SHOWERS THIS
AFTERNOON NORTH OF THE UMPQUA DIVIDE AND CRATER LAKE NORTH, BUT
THE SHORT RANGE HIS RES MODELS SHOW LITTLE OR NO QPF. THIS HAVE
REDUCED POPS MAINLY FOR THE SOUTHERN AND EASTERN PART OF THE CWA
AND ADJUSTED QPF VALUES DOWN FOR TODAY.

THE UPPER LOW/TROUGH WILL CONTINUE TO MOVE SOUTH OVER THE NEXT 48
HOURS KEEPING TEMPERATURES BELOW NORMAL. RAINFALL CHANCES WILL BE
GREATEST ON FRIDAY, MAINLY EAST OF THE CASCADES AND COULD BE
UNSTABLE ENOUGH FOR ISOLATED THUNDERSTORMS. -PETRUCELLI


&&

.AVIATION...FOR THE 02/12Z TAF CYCLE...A FRONT GRADUALLY MOVING
INLAND WILL BRING LOW CLOUDS AND SHOWERS TO THE COAST, THE UMPQUA
VALLEY AND INTO THE SOUTHERN OREGON CASCADES THIS MORNING. MVFR CIGS
WITH ISOLATED IFR CIGS ALONG THE COAST WILL GRADUALLY LIFT TO VFR AS
SHOWERS TAPER OFF AFTER AROUND 17Z-18Z. INLAND, THERE WILL BE MVFR
CIGS IN THE UMPQUA VALLEY AND LOCAL MVFR CIGS MAY ALSO SPREAD INTO
THE GRANTS PASS AREA THIS MORNING. CLOUDS AND AREAS OF SHOWERS WILL
ALSO BRING WIDESPREAD MOUNTAIN OBSCURATIONS FROM THE CASCADES WEST
IN SOUTHERN OREGON THROUGH THE MORNING...WITH PARTIAL OBSCURATIONS
CONTINUING INTO THE AFTERNOON. ELSEWHERE, EXPECT VFR CONDITIONS
THROUGH THE TAF PERIOD THOUGH LOW LEVEL WESTERLY WINDS FROM THE
CASCADES EASTWARD WILL BE GUSTY AND STRONG THIS AFTERNOON AND
EVENING DUE TO THE PASSAGE OF THE FRONT. /DW


&&

.MARINE...UPDATED 500 AM PDT WEDNESDAY 2 SEPTEMBER 2015...A COLD
FRONT HAS MOVED THROUGH THE NORTHERN PORTION OF THE WATERS AND WILL
CONTINUE THROUGH THE REMAINDER OF THE WATERS THIS MORNING. IT WILL
PRODUCE A FEW SHOWERS AND MODERATE NORTH WINDS WITH SEAS REMAINING
DOMINATED BY A MODERATE NORTHWEST SWELL. SEAS WILL INCREASE INTO
THIS EVENING...THEN GRADUALLY LOWER INTO FRIDAY MORNING. THE COASTAL
WATERS WILL BECOME DOMINATED BY MODERATE TO STRONG NORTH WINDS
THURSDAY THROUGH THE WEEKEND. WINDS WILL BE STRONGEST IN THE OUTER
WATERS SOUTH OF CAPE BLANCO WITH THE POTENTIAL FOR SMALL CRAFT
ADVISORY LEVEL WINDS TO DEVELOP IN THAT AREA AS EARLY AS THURSDAY
EVENING. WINDS WILL DIMINISH DURING THE OVERNIGHT HOURS THEN
INCREASE AGAIN FRIDAY AFTERNOON AND EVENING. MORE WIDESPREAD
COVERAGE OF ADVISORY LEVEL WINDS IS POSSIBLE ON SATURDAY, THEN WINDS
ARE FORECAST TO REACH A PEAK ON SUNDAY AFTERNOON WITH GALES POSSIBLE
IN THE SOUTHERN OUTER WATERS. STRONG NORTHERLY WINDS ARE LIKELY TO
PERSIST THROUGH EARLY NEXT WEEK. /DW


&&

.PREV DISCUSSION... /ISSUED 116 AM PDT WED SEP 2 2015/

DISCUSSION...02/00Z NAM/GFS IN.

SOUTHWEST FLOW ALOFT IS INCREASING AS A DIGGING LONG WAVE TROUGH
APPROACHES THE COAST. THIS TROUGH WILL MOVE INTO THE PACIFIC
NORTHWEST TUESDAY NIGHT INTO WEDNESDAY...FORCING  THE STORM TRACK
FARTHER SOUTH. THE INITIAL SURFACE FRONT WILL MOVE ONSHORE LATER
THIS MORNING. WITH LITTLE UPPER LEVEL SUPPORT IT WILL BE WEAK. THE
NORTH COAST WILL GET MOST OF THE PRECIPITATION...AND IT IS ALREADY
RAINING THERE. INLAND AMOUNTS FROM THE CASCADES WEST AND
SISKIYOUS NORTH WILL BE VERY LIGHT. FAR NORTHERN KLAMATH COUNTY
MAY GET SOME MEASURABLE RAIN TOO. INLAND HIGH TEMPERATURES WILL
COOL DOWN TO 5 TO 10 DEGREES BELOW NORMAL...EXCEPT OVER LAKE AND
MODOC COUNTIES...WHERE THE HIGHS WILL BE 3 T0 5 DEGREES BELOW
NORMAL.

A STRONGER FRONT WILL MOVE IN THIS AFTERNOON AND EVENING...AND
THIS WILL REINFORCE THE FIRST FRONT. PRECIPITATION WILL STILL BE
LIGHT...BUT IT WILL SPREAD TO THE EAST SIDE TONIGHT.  AS TYPICALLY
HAPPENS WITH INCOMING FRONTS...WINDS WILL BE GUSTY EAST OF THE
CASCADES THIS AFTERNOON AND EVENING.

ONCE THE LONG WAVE TROUGH SETS UP OVER THE PACIFIC NORTHWEST...IT
WILL HANG AROUND A WHILE AS SHORT WAVES DIVING DOWN THE BACKSIDE
OF THE TROUGH WILL KEEP IT DIGGING INTO FRIDAY NIGHT WITH A SLOW
EASTWARD PROGRESSION. THURSDAY AND FRIDAY LOOK TO BE COOL WITH
INLAND HIGHS 10 TO 15 DEGREES BELOW NORMAL. THERE IS THE POTENTIAL
THAT FROST/FREEZE HEADLINES MAY BE NEEDED FOR THE AGRICULTURAL
INTERESTS EAST OF THE CASCADES AND IN NORTHERN CALIFORNIA.

COOL AIR ALOFT WOULD NORMALLY SUPPORT SHOWER ACTIVITY...AND THE
MODEL SOLUTIONS HAVE FINALLY HIT ON THIS. THE NAM...EC AND GFS ARE
ALL MUCH WETTER THAN PREVIOUS RUNS...ESPECIALLY ON FRIDAY. AT
THIS POINT IT LOOKS LIKE IT WON`T BE UNSTABLE ENOUGH FOR
THUNDERSTORMS THURSDAY...SO JUST WENT WITH SHOWERS THEN EAST OF
THE CASCADES. FRIDAY LOOKS TO BE MORE UNSTABLE WITH MORE
WIDESPREAD ACTIVITY...SO GOING WITH AREAS OF SCATTERED SHOWERS
FROM THE CASCADES EAST AND SISKIYOUS SOUTH...AS WELL AS THE ROGUE
VALLEY. HOWEVER...WITH LIFTED INDICES TOPPING OUT AT AROUND
-2...THUNDERSTORM COVERAGE WILL LIKELY REMAIN ISOLATED.

BY SATURDAY MORNING...THE TROUGH AXIS WILL BE OVER CENTRAL AND
EASTERN OREGON AND HEADING EAST. THIS WILL SHIFT THE INSTABILITY
TO THE EAST AND NORTHWEST FLOW ALOFT WILL BRING IN MORE STABLE
CONDITIONS FOR THE WEST SIDE AND CASCADES. BY SATURDAY EVENING THE
SHOWERS WILL BE LIMITED TO THE FAR EAST SIDE. IT WILL BE WARMER
TOO WITH INLAND HIGHS 3 TO 5 DEGREES WARMER THAN THE FRIDAY HIGHS.

SUNDAY AND MONDAY LOOK TO BE DRY WITH A WARMING TREND AS
NORTHWEST FLOW ALOFT BECOMES ZONAL. INLAND HIGHS WILL WARM TO NEAR
NORMAL VALUES SUNDAY...THEN GO ABOVE NORMAL MONDAY.

THE GFS KEEPS TUESDAY DRY...BUT THE EC SUGGESTS ANOTHER FRONT WILL
MOVE ONSHORE AROUND THAT TIME.


&&

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

CA...NONE.

PACIFIC COASTAL WATERS...NONE.

$$



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