Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 290337
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
837 PM PDT MON JUL 28 2014

.DISCUSSION...THIS WAS THE HOTTEST DAY OF THE YEAR SO FAR IN
MEDFORD WITH A HIGH OF 106 THAT TOPPED THE 105 ON JULY 1ST. BUT,
IT STILL CAME UP A COUPLE OF DEGREES SHY OF THE RECORD SET IN
2009. IN FACT, THE ONLY RECORD TODAY WAS A TIE IN MT SHASTA CITY.
IT WAS ALSO 98 DEGREES THERE ON THIS DATE IN 2009. THE DEARTH OF
RECORDS DESPITE THE HEAT INLAND IS NOT THAT SURPRISING CONSIDERING
THAT ON AVERAGE THE LAST WEEK OF JULY AND FIRST WEEK OF AUGUST
ARE OUR HOTTEST TWO WEEKS OF THE YEAR.

THERE WERE A FEW THUNDERSTORMS THAT DEVELOPED LATE THIS
AFTERNOON INTO THE EARLY EVENING, MOST NOTABLE WERE A LONG-LASTING
CELL ALONG THE NORTHEAST DOUGLAS/SOUTHEAST LANE COUNTY BORDER AND
ANOTHER IN EXTREME SOUTHWEST SISKIYOU COUNTY. THIS SPARSE ACTIVITY
IS NOW BEGINNING TO DIMINISH WITH SEVERAL CELLS EAST OF THE
CASCADES THAT ARE LIKELY ONLY PRODUCING VIRGA. AS A RESULT, WE
WILL UPDATE TO ADJUST POPS DOWN FOR THE REMAINDER OF THE EVENING.

THE MAIN FOCUS THIS EVENING IS ON THE POSSIBLE NEED FOR
ADJUSTMENTS TO THE TUESDAY AND TUESDAY NIGHT FORECAST. THE 00Z NAM
DATA HAS JUST ARRIVED. ONCE THE SHORT TERM PORTION OF THE 00Z GFS
DATA ALSO HAS ARRIVED, WE WILL BEGIN TO MAKE A DETERMINATION ON
UPGRADING OR ADJUSTING THE FIRE WEATHER WATCH. THIS WATCH IS
CURRENTLY IN EFFECT FROM LATE TUESDAY MORNING THROUGH TUESDAY
EVENING ROUGHLY FROM THE CASCADE FOOTHILLS EASTWARD. THE NEW NAM
DATA IS VERY SIMILAR TO ITS PREVIOUS RUN WITH A FORECAST OF
SCATTERED THUNDERSTORMS FOCUSED FROM MOUNT SHASTA NORTHEASTWARD
INTO SOUTH CENTRAL OREGON. OUR CURRENT FORECAST IS IN LINE WITH
THE 18Z GFS AND INCLUDES SCATTERED THUNDERSTORMS OVER A LARGER
AREA...STRETCHING FARTHER WEST...FROM WESTERN SISKIYOU COUNTY
ACROSS THE SISKIYOU MOUNTAINS AND SOUTHERN PORTION OF THE ROGUE
VALLEY TO THE CASCADE MOUNTAINS THEN ACROSS THE EAST SIDE. BOTH
MODELS ARE IN AGREEMENT ON HIGHER MID-LEVEL MOISTURE AMOUNTS AND
AN AFTERNOON SHORTWAVE TRACKING NORTHWARD THAT WOULD SUPPORT A
HIGHER PROBABILITY OF THUNDERSTORMS ON TUESDAY COMPARED TO THIS
PAST AFTERNOON.

&&

.AVIATION...BASED ON THE 29/00Z TAFS...

AREAS OF LIFR CIGS IN LOW MARINE STRATUS WILL PERSIST ALONG THE
COAST FROM CAPE BLANCO NORTHWARD...BECOMING WIDESPREAD ALONG THE
DOUGLAS, COOS, AND CURRY COUNTY COAST AFTER 03Z AND PUSHING INTO
THE COQUILLE VALLEY AS WELL. AREAS OF IFR VISIBILITIES WILL
ALSO DEVELOP TONIGHT INTO EARLY TUESDAY MORNING ALONG THE COAST
AS FOG DEVELOPS. LOW CLOUDS AND FOG ARE EXPECTED TO CLEAR BACK
FROM THE COAST AROUND 19Z. INLAND...EXPECT VFR CONDITIONS THIS
EVENING THROUGH TUESDAY MORNING WITH ISOLATED CUMULUS OVER THE
HIGHER TERRAIN THAT WILL BE DISSIPATING. ISOLATED TO SCATTERED
THUNDERSTORMS ARE EXPECTED TO DEVELOP THOUGH IN THE AFTERNOON
ON TUESDAY OVER NORTHERN CALIFORNIA AND FROM THE CASCADE FOOTHILLS
EASTWARD IN OREGON. THESE STORMS WILL BRING GUSTY WINDS AND LOCAL
MVFR CIGS ARE POSSIBLE. /CC

&&

.MARINE...UPDATED 600 PM PDT 28 JULY 2014...

MODELS REMAIN IN AGREEMENT THAT THE CURRENT PATTERN WITH SOME SLIGHT
DAY-TO-DAY VARIATION WILL PERSIST THIS WEEK. HIGH PRESSURE IS
CENTERED OFFSHORE AND A THERMAL TROUGH OVER NORTHERN CALIFORNIA
WHICH WILL CONTINUE TO RESULT IN STEEP WIND WAVE DOMINATED SEAS AND
AREAS OF SMALL CRAFT ADVISORY WINDS. THROUGH MID-WEEK, THE STRONGEST
WINDS WILL OCCUR IN THE OUTER WATERS SOUTH OF CAPE BLANCO  AND
DURING THE AFTERNOON AND EVENING HOURS. MODELS INDICATE THAT WINDS
WILL INCREASE SLIGHTLY ON WEDNESDAY. THEN WIND SPEEDS AND SEAS ARE
FORECAST TO INCREASE FURTHER THURSDAY INTO FRIDAY. CONDITIONS MAY
INCREASE TO GALES WITH VERY STEEP SEAS LATE IN THE WEEK FOR AREAS
SOUTH OF CAPE BLANCO, WITH MODERATE NORTH WINDS AND STEEP SEAS OVER
THE COASTAL WATERS FROM CAPE BLANCO NORTH. /CC


&&

.PREV DISCUSSION... /ISSUED 256 PM PDT MON JUL 28 2014/

SHORT TERM...CUMULUS CLOUDS ARE FORMING ALONG THE CASCADES BEING
DENSEST FROM CRATER LAKE NORTH INTO DESCHUTES COUNTY.THE MARBLE
MOUNTAINS OF SISKIYOU COUNTY ARE ALSO SEEING MORE CU BUILDUP.
THERE IS STILL SOME CAPPING IN THOSE AREAS BUT IT COULD BE BROKEN
TOWARD THE EVENING. AS A RESULT EXPECT SOME OF THESE CU TO BUILD
INTO THUNDERSTORM CLOUDS WITH A FEW LIGHTNING STRIKES THIS
EVENING.

ON TUESDAY ANOTHER SHORT WAVE DISTURBANCE WILL MOVE INTO NORTHERN
CALIFORNIA IN THE AFTERNOON. THIS SHORT WAVE WILL BRING MORE
MOISTURE AND GREATER INSTABILITY TO OUR FORECAST AREA.
PRECIPITABLE WATER WILL ALSO BE INCREASING TO MORE THAN ONE INCH.
HAVE ISSUED A FIRE WEATHER FOR ABUNDANT LIGHTNING AND DRY FUEL FOR
MANY OF OUR FIRE WEATHER ZONES FOR TUESDAY. THE MOST FAVORABLE
LOCATION APPEARS TO BE FROM THE KLAMATH BASIN AND THE EAST SLOPES
OF THE CASCADES NORTH INTO DESCHUTES COUNTY. PART OF SE JACKSON
COUNTY MAY SEE SOME THUNDERSTORM BUT NOT THE ROGUE VALLEY ITSELF.

THIS PATTERN CONTINUES INTO WEDNESDAY AND THURSDAY WITH MORE
THUNDERSTORMS FROM THE CASCADE EAST. WHILE MODELS INDICATE LESS
DYNAMICS FOR NORTHERN CALIFORNIA..I DONT FEEL COMFORTABLE ENOUGH
AND HAVE KEPT THUNDERSTORMS IN THE FORECAST FOR NORTHERN
CALIFORNIA ALBEIT ONLY AS ISOLATED COVERAGE. /FB

LONG TERM...(FRIDAY THROUGH MONDAY) EXPECT LITTLE CHANGE IN THE
WEATHER PATTERN AS THE RIDGE AXIS SHIFTS WESTWARD BACK TOWARD THE
PACIFIC NW. BOTH THE GFS AND THE ECMWF ARE NOW IN LINE WITH HIGHER
850HPA TEMPERATURE NEXT WEEKEND, ALONG WITH THE PRESENCE OF A LOW
PRESSURE APPROACHING CAPE MENDOCINO CALIFORNIA LATE SATURDAY. THIS
PUT OUR FORECAST AREA UNDER DIFFLUENCE FLOW ALOFT NEXT WEEKEND FOR
CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS. /FB


FIRE WEATHER...CURRENT WATER VAPOR IMAGE SHOWS MONSOONAL MOISTURE
INCREASING FROM THE SOUTHEAST INTO NEVADA. MODELS HAVE BEEN IN
FAIRLY GOOD AGREEMENT THE PAST COUPLE OF DAYS SHOWING MID LEVEL
MOISTURE INCREASING TONIGHT THROUGH TUESDAY. AT THE SAME TIME, PWATS
ARE EXPECTED TO INCREASE TO OVER AN INCH AND INSTABILITY IS EXPECTED
TO BE GREATEST ALONG THE CASCADE CREST...EASTSIDE AND IN PORTIONS OF
NORTHERN CALIFORNIA. STORM MOVEMENT ON TUESDAY IS EXPECTED TO BE
NORTH TO NORTHEAST AND COULD BE SLOW MOVERS WITH 700 MB WINDS
BETWEEN 5-10 KTS.

THE GFS IS STRONGER WITH THE SHORTWAVE AND PAINTS OUT HIGHER QPF IN
MODOC AND EAST OF THE CASCADES AND SUGGEST STORMS COULD LINGER INTO
THE OVERNIGHT HOURS TUESDAY INTO WEDNESDAY MORNING. THE NAM AND EC
SHOW SIMILAR SOLUTIONS AND ARE WEAKER WITH THE SHORTWAVE AND SUGGEST
STORMS WILL DISSIPATE AFTER DARK. MUCH WILL DEPEND ON HOW THINGS
PLAY OUT TUESDAY AFTERNOON. IF THINGS DEVELOP CLOSE TO THE GFS
SOLUTION, THEN IT`S POSSIBLE THE WATCH OR RED FLAG WARNING (IF
UPGRADED) COULD EXTEND INTO THE OVERNIGHT PERIOD TUESDAY.

THUNDERSTORM THREAT CONTINUES WEDNESDAY, BUT THE MODELS HINT THAT
MUCH OF THE ACTION WILL SHIFT NORTH AND NORTHEAST OF THE AREA. WITH
THAT SAID, WE`LL STAY THE COURSE AND KEEP THE BEST CHANCE OF STORMS
EAST OF THE CASCADES AND EASTERN MODOC BECAUSE THE DETAILS ARE
LIKELY TO CHANGE. THUNDERSTORM THREAT IS EXPECTED TO CONTINUE INTO
NEXT WEEKEND. THE MAIN QUESTION WILL BE THE TIMING, LOCATION, TRACK
OF THE SHORTWAVES AND AREAS OF GREATEST INSTABILITY.

GIVEN CONTINUED DRY FUELS CONDITIONS AND SIGNIFICANT LIGHTNING
POTENTIAL, NUMEROUS FIRE STARTS ARE LIKELY. THESE STARTS MAY,
INITIALLY, PRESENT A FIRE SPREAD PROBLEM, BUT CONDITIONS SHOULD
PROVIDE SOME TIME TO FIND THEM BEFORE FIRES GET BIG. -PETRUCELLI

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...FIRE WEATHER WATCH FROM TUESDAY MORNING THROUGH TUESDAY EVENING
     FOR ORZ617-621>625.

CA...FIRE WEATHER WATCH FROM TUESDAY MORNING THROUGH TUESDAY EVENING
     FOR CAZ280>282-284-285.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS UNTIL 11 AM PDT
     THURSDAY FOR PZZ356-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 11 AM PDT THURSDAY
     FOR PZZ350-356-370-376.

$$

DW/CC





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