407
FXUS66 KMFR 182146
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
246 PM PDT FRI SEP 18 2020
DISCUSSION
THE UPPER LOW IS MOVING ONSHORE. THE LOCATION OF THE
UPPER LOW IS OVER THE NORTHWEST PART OF THE FORECAST AREAS
(NORTHWEST COOS COUNTY) AND THIS WILL CONTINUE TO MOVE NORTHEAST
THIS AFTERNOON THROUGH TONIGHT. THE LATEST SATELLITE IMAGE CLEARLY
SHOWS MOST OF THE ENERGY OUT AHEAD OF THE UPPER LOW (LIKE A
PINWHEEL) WHICH PUTS MOST OF THE ACTION IN TERMS OF SHOWERS AND
THUNDERSTORMS NORTH OF OUR FORECAST AREA. HOWEVER SCATTERED SHOWERS
AND ISOLATED STORMS ARE STILL A GOOD BET FOR MOST OF DOUGLAS COUNTY
AND NORTHERN CASCADES FROM ABOUT CRATER LAKE NORTH. THESE AREAS ALSO
HAVE THE BEST CHANCE OF GETTING MODERATE TO HEAVY SHOWERS INTO EARLY
THIS EVENING. THERE IS STILL CONCERN FOR MODERATE TO HEAVY RAIN IN A
SHORT PERIOD OF TIME TO SET UP NEAR OR OVER THE BURN SCARS OVER THE
ARCHIE CREEK FIRE AND A FLASH FLOOD WATCH HAS BEEN ISSUED. PLEASE
SEE FFAMFR FOR MORE DETAILS.
ONCE AGAIN WE WANT TO REMIND THE FOLKS OUT THERE OUR RADAR AT KMAX
IS CURRENTLY UNDERGOING THE SERVICE LIFE EXTENSION PROGRAM AND IS
NOT PROVIDING DATA. THE DATA PRESENTED ON OUR WEBSITE ARE FROM
SEPTEMBER 14TH. IF YOU FIND YOURSELF IN THE UNLIKELY POSITION OF
BEING WITHIN A WARNING AREA, YOU WILL NOT FIND ANY CURRENT RADAR
DATA FROM KMAX TO COMPARE THE WARNING TO. WE ALREADY HAVE THE GOES
WEST MESOSECTOR 1 PROVIDING US AND YOU WITH UP TO THE MINUTE
SATELLITE DATA. TRUST THAT YOU ARE INDEED IN A WARNING AREA AND TAKE
THE PRECAUTIONS YOU NEED TO KEEP YOURSELF SAFE BEFORE LOOKING FOR
OTHER DATA.
THE UPPER LOW WILL PROGRESS THROUGH THE AREA TONIGHT AND WILL BE
EAST OF THE CASCADES BY EARLY SATURDAY MORNING. SHOWERS AND ISOLATED
STORMS WILL DIMINISH THIS EVENING WITH SHOWERS GRADUALLY DIMINISHING
IN COVERAGE OVERNIGHT TONIGHT. SHOWERS WILL LINGER MAINLY NORTH OF
THE UMPQUA DIVIDE AND CASCADES TONIGHT.
THE UPPER TROUGH MOVES EAST OF OUR AREA SATURDAY MORNING WITH WEAK
RIDGING BUILDING FROM THE WEST. COULD NOT RULE OUT A FEW SHOWERS
NORTH OF THE UMPQUA DIVIDE AND NORTHERN CASCADES UNTIL ABOUT THE MID
MORNING HOURS SATURDAY, OTHERWISE IT WILL BE DRY WITH MILDER
TEMPERATURES IN THE AFTERNOON FOR MOST INLAND LOCATIONS.
SUNDAY, A WEAK THERMAL TROUGH WILL SET UP ALONG THE COAST WITH
INCREASING OFFSHORE FLOW IN SOUTHWEST OREGON, BUT WINDS WILL NOT BE
STRONG, EVEN OVER THE MID SLOPES AND RIDGES AND WILL BE SHORT LIVED.
BEYOND SUNDAY, IT SHOULD REMAIN DRY THROUGH AT LEAST THE MIDDLE OF
NEXT WEEK. A WEAK UPPER TROUGH AND COLD FRONT APPROACHES THE AREA
MONDAY, BUT THE MAIN EFFECT WILL BE INCREASING ONSHORE FLOW NEAR AND
AT THE COAST AND COOLER AFTERNOON TEMPERATURES FOR MOST INLAND
LOCATIONS. A STRONGER FRONT WILL ARRIVE NEXT THURSDAY. UNLIKE THE
LAST FRONT FROM EARLIER THIS WEEK AND YESTERDAY, WE WON'T HAVE A
STRONG UPPER RIDGE IN PLACE, INSTEAD WE'LL HAVE A WEST TO SOUTHWEST
FLOW WITH THE RIDGE SOUTH OF OUR AREA. THEREFORE THERE IS A BETTER
OPPORTUNITY FOR THE FRONT TO HOLD TOGETHER AND NOT WEAKEN, THUS
RESULTING IN A HIGHER CHANCE FOR MEASURABLE RAIN.
THE FRONT WILL MOVE THROUGH THE AREA THURSDAY NIGHT FOLLOWED BY AN
UPPER TROUGH FRIDAY WITH THE CHANCE FOR POST FRONTAL SHOWERS.
-PETRUCELLI
AVIATION...FOR THE 18/18Z TAFS
OVER THE COASTAL WATERS AND ALONG
THE COAST...WIDESPREAD MVFR CIGS WITH SHOWERS WILL PERSIST INTO
THIS EVENING, THEN SHOWERS END, BUT MVFR/IFR PREVAILS OVERNIGHT
INTO SATURDAY MORNING.
INLAND AREAS FROM THE CASCADES WEST...WILDFIRE SMOKE COVERAGE WILL
DECREASE THROUGH THIS EVENING, BUT EXPECT SHOWERS AND ISOLATED
THUNDERSTORMS TO OCCASIONALLY LOWER CONDITIONS TO MVFR/IFR THROUGH
THIS EVENING. AREAS OF HIGHER TERRAIN WILL ALSO BE OBSCURED.
EAST OF THE CASCADES...VFR CONDITIONS WILL PREVAIL THROUGH SATURDAY
MORNING EXCEPT FOR LOCAL MVFR VSBYS IN SMOKE AND HAZE. GUSTY WEST
WINDS WILL DEVELOP THIS AFTERNOON AND EVENING, DIMINISHING
OVERNIGHT. ISOLATED SHOWERS AND ISOLATED THUNDERSTORMS ARE
EXPECTED THIS AFTERNOON/EVENING, FOCUSED IN THE WESTERN PART OF THE
AREA. ANY SHOWERS WILL END TONIGHT. -SPILDE
NIGHT.
MARINE...UPDATED 200 PM PDT FRIDAY 18 SEPTEMBER 2020
RELATIVELY
CALM CONDITIONS WITH LIGHT SOUTH WINDS AND SEAS GENERALLY AT OR
BELOW 5 FEET WILL CONTINUE THROUGH SATURDAY MORNING. A THERMAL
TROUGH WILL BUILD NEAR THE COAST LATE SATURDAY INTO SUNDAY,
PRODUCING GUSTY NORTH WINDS AND CHOPPY WIND DRIVEN SEAS SOUTH OF
CAPE BLANCO. ALTHOUGH CONDITIONS ARE EXPECTED TO REMAIN
BELOW ADVISORY CRITERIA, WINDS WILL BE STRONGEST BEYOND 5 NM FROM
SHORE. THE THERMAL TROUGH WILL WEAKEN MONDAY AND WINDS AND SEAS
WILL SUBSIDE AT THAT TIME. SUB-ADVISORY CONDITIONS ARE THEN
EXPECTED THROUGH TUESDAY, THEN NORTHWEST SWELL WILL INCREASE
WEDNESDAY AS A NEW SERIES OF FRONTS APPROACHES THE AREA. -SPILDE
UPDATED 230 PM PDT FRIDAY 18 SEPTEMBER
2020...EAST OF THE CASCADES, SOME VERY BREEZY WINDS TO 40 MPH ARE
OCCURING, ESPECIALLY AT THE HIGHER ELEVATIONS. MEANWHILE, 20-25
MPH WIND GUSTS ARE EXPECTED AT SOME OF THE MEDIUM ELEVATIONS.
ELSEWHERE, SHOWERS AND A COUPLE OF THUNDERSTORMS ARE EXPECTED THIS
AFTERNOON AND EVENING. THE WETTEST STORMS WILL BE NORTH OF THE
UMPQUA DIVIDE AND ALONG AND WEST OF THE CASCADES WHICH COULD STILL
PUT DOWN SOME WETTING RAIN, ESPECIALLY THE FARTHER NORTH ONE
GOES. SOUTH OF THE UMPQUA DIVIDE THE CHANCES FOR WETTING RAINS ARE
SHARPLY DECREASING, AND SOME OF OUR WEST SIDE VALLEYS (ROGUE
VALLEY) MAY NOT EVEN GET MEASURABLE RAIN, LET ALONE AREAS EAST OF
THE CASCADES. REGARDLESS, WE WILL KEEP LAL 2 FOR MUCH OF THE AREA
ON THE OFF CHANCE THAT A STRAY THUNDERSTORM DEVELOPS.
THE UPPER LOW CAUSING THESE SHOWERS AND A FEW STORMS WILL EXIT THE
AREA QUICKLY OVERNIGHT ALLOWING THINGS TO CLEAR UP AND BEGIN DRYING
OUT TOMORROW (A FEW LINGERING LIGHT SHOWERS ARE POSSIBLE SATURDAY
MORNING FOR THE UMPQUA BASIN AND THE CASCADES NORTH OF CRATER LAKE).
THEN, LIGHT EAST WINDS ON SATURDAY NIGHT WILL ALLOW THINGS TO DRY
OUT TOWARD NORMAL FOR THIS TIME OF YEAR. TEMPERATURES WILL ALSO
CLIMB TO BE NEAR NORMAL BY SUNDAY. OUR DRY WEATHER WILL CONTINUE
INTO NEXT WEEK, BUT CRITICAL CONDITIONS ARE NOT EXPECTED. A FRONT
TOWARD THE END OF THE WEEK COULD BE A BIT MORE PROMISING FOR
RAINFALL THAN THIS SYSTEM; BUT THINGS ARE LIKELY TO CHANGE BETWEEN
NOW AND THEN. -SCHAAF
MFR WATCHES/WARNINGS/ADVISORIES
OR...FLASH FLOOD WATCH UNTIL 8 PM PDT THIS EVENING FOR ORZ023-025.
CA...NONE.
PACIFIC COASTAL WATERS...NONE.
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