Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 060416
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
916 PM PDT SUN JUL 5 2015

.DISCUSSION...THUNDERSTORMS HAVE DISSIPATED ACROSS AREAS WEST OF
THE CASCADES AND AS OF 9 PM WERE CONFINED TO LAKE AND EASTERN
MODOC COUNTY. THE STORMS THIS AFTERNOON PRODUCED MODERATE TO HEAVY
RAIN WITH LOCALIZED FLOODING REPORTED IN KLAMATH FALLS.
THUNDERSTORM AREAS FOLLOW THETA-E AXIS FAIRLY WELL AND THIS MAY BE
A GOOD PLACE TO FOLLOW FOR MONDAY STORM. /FB

&&

.AVIATION...FOR THE 06/00Z TAF CYCLE...ALONG THE COAST...IFR CIGS
WILL PERSIST OVERNIGHT...AND LOWER TO LIFR IN AREAS ALONG THE COAST.
ALSO EXPECT PATCHY FOG TO LOWER VISIBILITIES TO MVFR ALONG THE
COAST...WITH AREAS OF IFR VIS. ELSEWHERE...SCATTERED THUNDERSTORMS
WILL PERSIST INTO THIS EVENING FROM THE CASCADES EAST AND SISKIYOUS
SOUTH...WITH A CHANCE FOR THUNDERSTORMS IN THE ROGUE VALLEY.
THUNDERSTORMS ARE POSSIBLE MONDAY AFTERNOON...WITH THE HIGHEST
CHANCE OVER THE CASCADES AND EAST. -MSC

&&

.MARINE...UPDATED 600 PM PDT SUNDAY 5 JULY 2015...WITH LIGHT WINDS
STRATUS WILL INCREASE OVER MOST OF THE COASTAL WATERS TODAY. PATCHY
FOG IS EXPECTED TONIGHT...AND WILL CLEAR LATE MONDAY MORNING. LIGHT
TO MODERATE WESTERLY WINDS WILL PERSIST TODAY...BACKING TO SOUTHERLY
OVERNIGHT. WINDS WILL BE LIGHT AND SLOWLY SHIFT NORTH TO NORTHWEST
MIDWEEK...AS PRESSURE BUILDS OFFSHORE AND DROPS INLAND. LOW
NORTHWESTERLY SWELL WILL CONTINUE THROUGH THE WEEK. CONDITIONS WILL
STAY BELOW ADVISORY CRITERIA THROUGH AT LEAST MIDWEEK. BOTH GFS AND
EC SHOW AN UPPER LOW FORMING OFF THE CENTRAL CA COAST AND MOVING
INTO SOUTHERN CA LATER IN THE WEEK. THIS WILL ENCHANCE NORTHERLY
WINDS...ESPECIALLY IN THE SOUTHERN WATERS...BUT THERE IS STILL MODEL
DISCREPANCY REGARDING THE STRENGTH OF THE LOW...SO IT`S TOO SOON TO
DETERMINE WHETHER ADVISORY CONDITIONS WILL BE MET. -MSC

&&

.FIRE WEATHER...UPDATED 800 PM PDT SUNDAY 5 JULY 2015...LIGHTNING
STRIKES HAVE SHIFTED EAST TO MAINLY HIGHWAY 395 FROM THE ABERT
RIM SOUTH THROUGH MODOC COUNTY. EXPECT QUICK DECREASE THIS EVENING
AS WE LOSE SURFACE HEATING. THUNDERSTORM ACTIVITY WILL BE SLIGHTLY
LESS WIDESPREAD MONDAY...BUT WILL INCREASE TUESDAY AND WEDNESDAY.
THE FAVORED AREA ON MONDAY ACTIVITY WILL BE MOSTLY OVER THE HIGHER
TERRAIN FROM THE CASCADES EAST AND SISKIYOUS SOUTH. TUESDAY AND
WEDNESDAY WILL SEE GREATER COVERAGE. EVEN THE COASTAL AREA MAY SEE
SOME THUNDERSTORMS IN THAT TIME FRAME. THE ACTIVITY WILL GRADUALLY
SHIFT TO THE EAST SIDE TOWARD THE END OF THE WEEK.

TEMPERATURES WILL REMAIN HOT MONDAY...BUT WILL START TO COOL
TUESDAY. TEMPERATURES WILL APPROACH SEASONAL VALUES TOWARD THE
END OF THE WEEK. /FB

&&

.PREV DISCUSSION... /ISSUED 313 PM PDT SUN JUL 5 2015/

DISCUSSION...SATELLITE IMAGERY TODAY SHOWS THE MEDFORD CWA IN BETWEEN TWO
REGIMES...WITH A CUTOFF LOW OFFSHORE FROM CA AND A WEAK BOUNDARY TO
THE NORTH. GOOD ATMOSPHERIC STRETCHING IS OCCURRING WITH EAST WINDS
ALOFT ON THE WEST HALF OF THE FORECAST AREA AND WEST WINDS ALOFT ON
THE EAST SIDE OF THE FORECAST AREA. THIS DEFORMATION ZONE IS A
FAVORABLE AREA FOR THUNDERSTORMS...POTENTIALLY STRONG TO
SEVERE...AND EAST OF THE CASCADES IS WHERE THE DEEPEST MOISTURE
IS TO SUPPORT SCATTERED THUNDERSTORMS. A RED FLAG WARNING AT
RFWMFR CONTINUES THROUGH THIS EVENING FOR PARTS OF NORTHERN
CALIFORNIA...AND PORTIONS OF KLAMATH AND LAKE COUNTIES. A MASS OF
CLOUDS PRESENT EARLIER TODAY IS BEGINNING TO CLEAR FROM SOUTH TO
NORTH AND IS RESULTING IN INCREASED SUNSHINE AND ENHANCED
INSTABILITY.

TONIGHT...STORMS SHOULD DIMINISH AS MOISTURE IN THE ATMOSPHERE
BECOMES LIMITED AND DIURNAL OVERNIGHT STABILITY TAKES HOLD. ON
MONDAY THERE IS SOME LINGERING MOISTURE...BOTH SFC MOISTURE FROM
RECENT RAINS AND MID LEVEL MOISTURE...BUT THE MID LEVEL MOISTURE
WILL BE LESS THAN TODAY. PERHAPS THE MOST CHALLENGING ASPECT OF
THE THUNDERSTORM FORECAST TOMORROW IS THE FACT THAT THE MODELS
ARE NOT SHOWING A GOOD TRIGGER FOR MONDAY AFTERNOON.
TYPICALLY...ITS DIFFICULT TO GET SCATTERED THUNDERSTORMS WITH WEAK
TRIGGERS. THEREFORE...WE ARE MAINTAINING A FIRE WEATHER WATCH FOR
TOMORROW AT RFWMFR AND WILL LET THE MIDSHIFT TAKE ONE MORE LOOK AT
THINGS BEFORE DECIDING ON PRODUCTS. WE HAVE FOCUSED THE BEST
POTENTIAL FOR SCATTERED THUNDERSTORMS OVER THE CASCADES NORTH OF
CRATER LAKE...AND JUST TO THE EAST...WHERE MID LEVEL MOISTURE
VALUES OF 50- 60% ALIGN WITH INSTABILITY.

ON MONDAY NIGHT AND TUESDAY THE WEATHER PATTERN BECOMES EVEN MORE
ACTIVE...WITH SOLID EAST SOUTHEAST FLOW ALOFT...AND VERY HIGH
PRECIPITABLE WATERS OF 1 INCH+ ALONG AND WEST OF THE CASCADES. THESE
ARE ANOMALOUSLY HIGH VALUES...AND WITH MODELS NOW ON THE SECOND DAY
OF SHOWING THIS SCENARIO...WE HAVE INCREASED POPS AND QPF FOR
MUCH OF THE SOUTHERN TWO-THIRDS OF THE FORECAST AREA. WEDNESDAY
SHOWS A SIMILAR PATTERN...BUT WITH FOCUS OF INSTABILITY AND
MOISTURE A BIT FURTHER SOUTH. THERE IS CERTAINLY A GOOD CHANCE FOR
MUCH OF THE FORECAST AREA...FROM THE UMPQUA DIVIDE SOUTH...TO SEE
A THUNDERSTORM SOMETIME BETWEEN TUESDAY AND WEDNESDAY. IN
FACT...WE HAVE THUNDERSTORM CHANCES ALL THE WAY TO THE COAST FROM
MONDAY NIGHT INTO TUESDAY. ON THURSDAY THE UPPER LOW FINALLY
SLOWLY PUSHES INLAND...WHICH THE MODELS HAVE BEEN FAIRLY
CONSISTENT IN SHOWING THE PAST FEW DAYS...BUT THIS MAINTAINS
FAVORABLE DYNAMICS AND INSTABILITY OVER THE AREA THROUGH FRIDAY
BEFORE WEST WINDS ALOFT BEGIN TO STABILIZE AND DRY THINGS OUT ON
SATURDAY FROM WEST TO EAST. THE WEEKEND MAY SIGNAL A BREAK FROM
THE STEADY CHANCES OF THUNDERSTORMS...BUT SOUTHERLY FLOW REBOUNDS
ON SUNDAY BASED ON THE LATEST GFS RUN.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING UNTIL 11 PM PDT THIS EVENING FOR ORZ623>625.
     FIRE WEATHER WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING
     FOR ORZ623>625.

CA...RED FLAG WARNING UNTIL 11 PM PDT THIS EVENING FOR
     CAZ280-281-284-285.
     FIRE WEATHER WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING
     FOR CAZ285.

PACIFIC COASTAL WATERS...NONE.

$$

FJB/FJB/FJB



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