914
FXUS66 KMFR 120417
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
917 PM PDT SUN APR 11 2021
UPDATE
AN UPDATE TO THE FORECAST IS NOT NECESSARY. SKIES WILL
REMAIN CLEAR OVERNIGHT WITH LOWS GENERALLY A FEW DEGREES ABOVE THE
VALUES FROM THIS MORNING. BUT, THAT WILL STILL BE A FEW TO SEVERAL
DEGREES BELOW NORMAL. A FROST ADVISORY REMAINS IN EFFECT FOR THE
EARLY MORNING HOURS IN THE COQUILLE VALLEY AND ALONG THE COAST OF
COOS AND DOUGLAS COUNTIES.
THE RECENT PATTERN OF DRY WEATHER WITH GENERALLY BELOW NORMAL LOW
TEMPERATURES AND ABOVE NORMAL HIGH TEMPERATURES WILL LIKELY
CONTINUE THROUGH THE UPCOMING WEEKEND.
ARGUABLY THE MOST IMPACTFUL PORTION OF THE FORECAST WILL BE
ASSOCIATED WITH A TROUGH RETROGRADING FROM THE ROCKIES NOW INTO
EASTERN OREGON BY TUESDAY. EAST-SIDE NORTHEAST WINDS WILL LIKELY
REACH A PEAK TUESDAY INTO TUESDAY EVENING WITH GUSTS OF 25 TO 40
MPH, WITH WEST-SIDE GUSTS REACHING 15 TO 30 MPH.
THIS WILL ALSO BRING AN INCREASE OF MAINLY MID-LEVEL MOISTURE TO
THE EAST SIDE. VIRGA IS A GOOD BET WITH DRY AIR AT THE LOW LEVELS.
BUT, THE HIGHEST PROBABILITY OF LIGHT SHOWERS SURVIVING TO THE
GROUND IS IN LAKE AND MODOC COUNTIES. AS IS TYPICAL WITH CLOSED
LOWS...THERE IS A MODERATE AMOUNT OF VARIABILITY IN JUST HOW FAR
SOUTH AND WEST THE TROUGH WILL TRACK, AND HOW MUCH MOISTURE WILL
BE AVAILABLE. BUT, WE COULD ENVISION COVERING A LONGER DURATION
AND WIDER SWATH OF LAKE AND MODOC COUNTIES WITH AT LEAST A SLIGHT
CHANCE OF SHOWERS TUESDAY THROUGH WEDNESDAY. A FEW RUMBLES OF
THUNDER ARE ALSO WITHIN THE REALM OF POSSIBILITY FOR THE FAR EAST
SIDE DURING PEAK HEATING OF LATE TUESDAY AFTERNOON.
AVIATION...FOR THE 12/00Z TAF CYCLE
VFR WILL CONTINUE THROUGH
MONDAY NIGHT. GUSTY NORTH WINDS AT 20 TO 35 KT ARE EXPECTED ALONG
THE COAST THROUGH THIS EVENING AND AGAIN MONDAY AFTERNOON AND
EVENING, INCLUDING KOTH. NORTH WINDS WILL ALSO BE GUSTY UP TO 20 KT
IN THE UMPQUA BASIN, INCLUDING KRBG, EARLY THIS EVENING AND MONDAY
AFTERNOON INTO EARLY EVENING. -DW
MARINE...UPDATED 815 PM PDT SUNDAY, 11 APR 2021
MODERATE TO
STRONG WINDS AND STEEP TO VERY STEEP SEAS ARE EXPECTED THROUGH
MONDAY NIGHT. NORTHERLY GALES WILL AFFECT AREAS GENERALLY BEYOND 5NM
FROM SHORE SOUTH OF CAPE BLANCO WHILE MOST OF THE REMAINING COASTAL
WATERS WILL BE IMPACTED BY VERY STEEP AND HAZARDOUS WARNING LEVEL
SEAS. WINDS AND SEAS WILL BE AT THEIR HIGHEST DURING THE AFTERNOONS
AND EVENINGS THROUGH MONDAY EVENING. SOME HIGH RESOLUTION MODELS
KEEP WINDS GUSTY ALL THE WAY TO THE COASTLINE THROUGH MONDAY NIGHT,
AND THUS WE EXPANDED THE HAZARDOUS SEAS WARNING TO COVER MOST OF THE
WATERS THROUGH MONDAY NIGHT.
WINDS ARE EXPECTED TO DIMINISH TUESDAY BUT WILL TICK UPWARDS AGAIN
ON TUESDAY AFTERNOON, LIKELY KEEPING SMALL CRAFT ADVISORY CONDITIONS
FOR MOST AREAS, WITH HAZARDOUS SEAS REMAINING POSSIBLE GENERALLY
SOUTH OF GOLD BEACH BEYOND 10NM FROM SHORE.
IT'S LIKELY THAT WINDS AND SEAS FINALLY DIP BELOW SMALL CRAFT
ADVISORY LEVEL FOR ALL AREAS BY THURSDAY. -SPILDE/KEENE
PREV DISCUSSION
/ISSUED 248 PM PDT SUN APR 11 2021/
SHORT TERM...THIS AFTERNOON THROUGH TUESDAY NIGHT...WITH HIGH
PRESSURE ALOFT AND A THERMAL TROUGH AT THE SURFACE, SKIES ARE
CLEAR ACROSS THE AREA THIS AFTERNOON. THE THERMAL TROUGH IS
BRINGING ENHANCED AFTERNOON BREEZES TODAY, WITH GUSTY WINDS ALONG
THE COAST AND ACROSS THE HIGHER TERRAIN. AFTERNOON TEMPERATURES
TODAY WILL BE AROUND 5 TO 10 DEGREES WARMER THAN WHAT OCCURRED
YESTERDAY. DRY CONDITIONS AND CLEAR SKIES WILL CONTINUE THIS
EVENING AND OVERNIGHT AND ANOTHER CHILLY NIGHT IS EXPECTED ACROSS
THE REGION. ALTHOUGH OVERNIGHT TEMPERATURES WILL BE WARMER THAN
LAST NIGHT, VALUES WILL STILL BE CONDUCIVE FOR FROST POTENTIAL
ALONG THE COAST NORTH OF CAPE BLANCO AND INTO THE COQUILLE BASIN.
AS SUCH, HAVE ISSUED A FROST ADVISORY FOR THAT AREA FOR TONIGHT,
AND DETAILS CAN BE FOUND AT NPWMFR. THE REMAINDER OF THE AREA WILL
BE WARMER BY AROUND 3 TO 5 DEGREES, SO WE AREN'T EXPECTING ANY
WIDESPREAD FREEZE CONDITIONS FOR WEST SIDE VALLEYS TONIGHT.
CONDITIONS ON MONDAY WILL BE QUITE SIMILAR TO THOSE OF TODAY,
ALTHOUGH AFTERNOON TEMPERATURES WILL TREND HIGHER BY ANOTHER 5 TO
10 DEGREES.
MONDAY EVENING INTO TUESDAY, AN UPPER LEVEL TROUGH DIGS OVER THE
PACIFIC NORTHWEST AND LINGERS THROUGH MUCH OF THE WEEK. THIS WILL BE
AN "INSIDE SLIDER" SO THERE WON'T BE MUCH MOISTURE ASSOCIATED WITH
IT DUE TO THE MOSTLY OVER LAND TRAJECTORY. CONDITIONS SHOULD REMAIN
LARGELY DRY, HOWEVER, A DECENT AMOUNT OF ENSEMBLES, BOTH THE GEFS
AND EC, SHOW SOME LIGHT PRECIPITATION (<0.02") OVER FAR EASTERN
PORTIONS OF LAKE AND MODOC COUNTIES ON TUESDAY AFTERNOON. GIVEN THE
MOSTLY OVER LAND TRAJECTORY, AND PRECEDING DRY AIR MASS, AM
SKEPTICAL THAT ANY PRECIPITATION WILL MAKE IT TO THE GROUND.
HOWEVER, THERE IS SOME OVER WATER TRAJECTORY WHICH WOULD ALLOW FOR
SOME MOISTURE TO BE ENTRAINED IN THE SYSTEM, AND GIVEN THE AMOUNT OF
ENSEMBLE SHOWING THE POSSIBILITY, HAVE LEFT IN A SLIGHT CHANCE
POPS ACROSS FAR EASTERN PORTIONS OF MODOC COUNTY. THE MORE NOTICEABLE
ELEMENT OF THIS UPPER LEVEL TROUGH WILL BE GUSTY WINDS ON TUESDAY.
IT WILL BE BREEZY EVERYWHERE IN THE FORECAST AREA TUESDAY, BUT
ESPECIALLY SO ACROSS THE EAST SIDE WHERE GUSTS OF 25 TO 35 MPH WILL
BE COMMON. THE TRAJECTORY OF THIS LOW BRINGS THE STRONGEST 700 MB
WINDS OVER THE COASTAL WATERS, AND WITH 700 MB WINDS ACROSS THE EAST
SIDE LIMITED TO 25 TO 30 KT, WIND SPEEDS SHOULD REMAIN BELOW
ADVISORY CRITERIA. IT SHOULD BE NOTED, HOWEVER, THAT IT HAS BEEN
QUITE SOME TIME SINCE THE AREA HAS RECIEVED WETTING RAINS (ABOUT
THREE WEEKS) AND THESE STRONG WINDS WILL BE COUPLED WITH MINIMUM
HUMIDITIES SIMILAR TO SUMMER-TIME VALUES. GIVEN THE DRY STATE OF
THINGS, USE CAUTION IF DEALING WITH ANYTHING THAT COULD POTENTIALLY
START A FIRE. WINDS WILL EASE TUESDAY NIGHT, BUT LOW PRESSURE
REMAINS OVER THE REGION AS WE HEAD INTO THE EXTENDED. /BR-Y
LONG TERM...WEDNESDAY THROUGH SUNDAY...THE GUSTY WINDS ON THE EAST
SIDE WILL BEGIN TO CALM AS THE LOW PRESSURE SYSTEM STALLS AND
WEAKENS. VERY DRY HUMIDITIES WILL, HOWEVER, CONTINUE SINCE WE WILL
REMAIN IN NORTH TO NORTHEAST FLOW. THIS PERIOD OF MILD TO WARM, DRY,
AND BREEZY CONDITIONS WILL CONTINUE TO ERODE SNOWPACK FOR MOST OF
THE EXTENDED FORECAST TIMEFRAME.
THE OVERALL FORECAST WE ARE CREATING SHOWS LITTLE DIFFERENCE BETWEEN
RUNS. YESTERDAY, I MENTIONED A POTENTIAL TRADE-OFF BETWEEN SHOWERS
AND STORMS AND THE GUSTY WINDS AND VERY LOW HUMIDITIES. THIS WAS
BASED ON THE TRACK OF THE LOW AND ITS WESTWARD SHIFT IN TRACK.
THINGS LOOK VERY SIMILAR TODAY, AND THE BEST CHANCE FOR
PRECIPITATION TO OCCUR IN THE EXTENDED IS TUESDAY NIGHT INTO EARLY
WEDNESDAY MORNING. THIS WOULD LOOK LIKE SHOWERS AND A POSSIBLE
THUNDERSTORM OVER THE WARNER MOUNTAIN IN MODOC COUNTY, BUT AM STILL
NOT OF THE BELIEF THAT THE SLIGHT WESTWARD TRACK WOULD BE ENOUGH TO
1.) PROVIDE ENOUGH MOISTURE TO INITIATE CLOUD COVER OR CONVECTION.
2.) OVERCOME THE VERY DRY AIR MASS NEAR THE SURFACE FROM THE
RESULTANT EASTERLY FLOW. THIS MEANS THAT ANY PRECIPITATION WOULD
EVAPORATE BEFORE REACHING THE GROUND.
THEREFORE, HAVE CONTINUED THE DRIER AND BREEZIER PORTION OF THE
NATIONAL BLEND OF MODELS THAT INCORPORATES THE ECMWF ENSEMBLES FOR
NOW. -SCHAAF
MFR WATCHES/WARNINGS/ADVISORIES
OR...FROST ADVISORY FROM 2 AM TO 9 AM PDT MONDAY FOR ORZ021.
CA...NONE.
PACIFIC COASTAL WATERS...GALE WARNING UNTIL 5 AM PDT TUESDAY FOR
PZZ356-376.
HAZARDOUS SEAS WARNING UNTIL 5 AM PDT TUESDAY FOR
PZZ350-356-370-376.
SMALL CRAFT ADVISORY UNTIL 5 AM PDT TUESDAY FOR PZZ350.
DW/MAS/BR-Y
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