Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 282156
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
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

&&

.AVIATION...BASED ON THE 28/18Z TAFS...

LATEST VISIBLE IMAGE SHOWS THE MARINE STRATUS HUGGING ALONG THE
COAST FROM CAPE BLANCO NORTH. RIGHT NOW, IT`S JUST WEST OF KOTH, BUT
THERE IS A CHANCE THE STRATUS COULD MOVE IN AND OUT OF THE AREA INTO
EARLY THIS EVENING BEFORE REMAINING OVERHEAD AFTER 0Z. THE TAF SHOWS
VFR BEING THE PREDOMINATE CONDITION PRIOR TO THEN, BUT CONFIDENCE IS
LOW TO MODERATE IT WILL REMAIN THAT WAY. ELSEWHERE...VFR CONDITIONS
WILL CONTINUE FOR THE NEXT 24 HOURS WITH CUMULUS BUILDUPS
DISSIPATING BETWEEN 3-5Z. MID-LEVEL MOISTURE WILL INCREASE TUESDAY
WITH ISOLATED TO SCATTERED THUNDERSTORMS FROM THE CASCADES FOOTHILLS
EASTWARD IN OREGON AND IN MODOC COUNTY IN NORTHERN CALIFORNIA.
-PETRUCELLI

&&

.MARINE...UPDATED 230 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 IS OVER NORTHERN CALIFORNIA
WHICH WILL CONTINUE TO RESULT IN STEEP WIND WAVE DOMINATED SEAS. THE
STRONGEST WINDS WILL OCCUR IN THE OUTER WATERS SOUTH OF CAPE BLANCO
AND DURING THE AFTERNOON AND EVENING HOURS. A VERY SLIGHT WEAKENING
IN THE PRESSURE GRADIENT WILL PERSIST THROUGH WEDNESDAY, THEN WIND
SPEEDS AND SEAS ARE FORECAST TO INCREASE A BIT THURSDAY INTO
FRIDAY.

&&

.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.

$$

FJB/FJB/MAP






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