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FXUS66 KMFR 310429
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
929 PM PDT SAT MAY 30 2020
UPDATE
BANDS OF RAIN CONTINUE TO DIMINISH AND NARROW TOWARDS
THE WEST SIDE CASCADE FOOTHILLS AND THE CASCADES TONIGHT. NO
LIGHTNING HAS BEEN OBSERVED FOR THE PAST SEVERAL HOURS AS A
STRONG INVERSION HAS SET IN OVER THE FORECAST AREA. HAVE ADJUSTED
TO DECREASE THE AREA OF PRECIPITATION TONIGHT. SVEN
PREV DISCUSSION
/ISSUED 502 PM PDT SAT MAY 30 2020/
UPDATED AVIATION DISCUSSION.
DISCUSSION...MODELS HAVE BEEN ADVERTISING THE POTENTIAL FOR
STORMS FOR SEVERAL DAYS NOW, AND TODAY'S STORMS PANNED OUT GENERALLY
AS EXPECTED. EARLY THIS MORNING ABOUT 200 CLOUD TO GROUND LIGHTNING
FLASHES IMPACTED AREAS WEST OF I-5, IN THE KALMIOPSIS AND NORTHWARD
INTO THE UMPQUA BASIN. THEN, ON THE NORTHERN PERIPHERY OF THE RAIN
SHIELD MORE STORMS DEVELOPED LATER IN THE MORNING, IMPACTING
JACKSON, DOUGLAS, AND CENTRAL AND EASTERN SISKIYOU COUNTIES. THESE
LATER STORMS WERE STRONG AND FEATURED HEAVY RAIN AND PLENTY OF
LIGHTNING. A FEW HOURS LATER, SEVERE STORMS IMPACTED AREAS ALONG AND
JUST EAST OF HIGHWAY 97. GOLF BALL SIZED HAIL WAS REPORTED FROM ONE
OF THE STORMS. IN TOTAL, ABOUT 900 CLOUD TO GROUND LIGHTNING FLASHES
WERE OBSERVED OVER OUR 9-COUNTY WARNING AREA SINCE EARLY THIS
MORNING. THE THREAT OF SEVERE STORMS IS DIMINISHING THIS AFTERNOON
AS STABILITY INCREASES FROM WEST TO EAST THROUGH THE EVENING.
ACTIVE WEATHER WILL BE ON THE DECREASE THIS EVENING WITH MOST, IF
NOT ALL OF THE ACTION NORTH OF OUR FORECAST AREA. STILL COULD NOT
RULE OUT ISOLATED STORMS IN NORTHERN KLAMATH AND LAKE COUNTY
EARLY THIS EVENING WITH GUSTY WINDS, BUT WE DON'T THINK ANY OF
THEM WILL BE SEVERE.
THE UPPER TROUGH AXIS WILL SHIFT TO THE NORTH LATER THIS EVENING AND
TONIGHT WITH SHOWERS DECREASING LATER THIS EVENING AND OVERNIGHT
TONIGHT. LOW TEMPERATURES TONIGHT FOR INLAND AREAS WILL END UP
COOLER.
SUNDAY SHOULD BE A DRY DAY FOR MOST HOURS AND LOCATIONS AS WEAK
SHORTWAVE RIDING BUILDS IN. HOWEVER THERE MAY BE ENOUGH INSTABILITY
FOR A FEW ISOLATED SHOWERS LATE IN THE AFTERNOON AND EARLY EVENING
IN PORTIONS OF THE CASCADES AND EASTSIDE. KEPT IN A SLIGHT CHANCE OF
THUNDER NEAR AND OVER THE WARNERS IN EASTERN MODOC COUNTY WHERE
INSTABILITY WILL BE A LITTLE GREATER.
WEAK TROUGHINESS REMAINS OVER THE AREA TONIGHT INTO MONDAY AND COULD
NOT RULE OUT ISOLATED SHOWERS ALONG THE CASCADES AND PARTS OF THE
EAST SIDE. ISOLATED THUNDERSTORMS ARE ALSO POSSIBLE MONDAY AFTERNOON
AND EVENING FOR THE EASTSIDE.
THE GENERAL CONSENSUS IS FOR THE UPPER TROUGH OFF THE CALIFORNIA
COAST TO BECOME SPLIT OFF FROM THE MAIN FLOW AND MOVE SOUTH OFF THE
CALIFORNIA COAST MONDAY NIGHT THROUGH THURSDAY. THEREFORE, WE COULD
CATCH A BREAK IN THE WEATHER TUESDAY, WEDNESDAY AND THURSDAY. IN
ADDITION, THE MAJORITY OF THE INDIVIDUAL ENSEMBLE MEMBERS (GFS AND
ECMWF) CONTINUE TO SHOW NO MEASURABLE PRECIPITATION WHICH HAS BEEN
THE CASE FOR THE PAST SEVERAL MODEL RUNS. THUS, CONFIDENCE IS
BECOMING HIGHER FOR DRIER CONDITIONS TUESDAY-THURSDAY. POPS HAVE
BEEN REDUCED DURING THIS TIME PERIOD AND MAY NEED TO BE REDUCED EVEN
FURTHER SHOULD ALL THE DATA CONTINUES TO SUPPORT DRY CONDITIONS.
ALSO MAX TEMPERATURES WERE ADJUSTED HIGHER.
FRIDAY, THE OPERATIONAL ECMWF AND GFS SHOW A DEEPER UPPER TROUGH
APPROACHING FROM THE PACIFIC BUT DIFFER WITH THE STRENGTH (THE ECMWF
DIGS THE UPPER TROUGH FURTHER SOUTH). EITHER WAY, IT WILL RESULT IN
SOME COOLING AND A BETTER CHANCE FOR SHOWERS TOWARDS THE END OF THE
WEEK MAINLY EAST OF THE CASCADES FRIDAY AFTERNOON AND NIGHT. NEXT
SATURDAY LOOKS COOLER AND UNSETTLED WITH A BETTER CHANCE FOR SHOWERS
ALMOST EVERYWHERE AND A SLIGHT CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS FOR PORTIONS OF THE EASTSIDE. OF NOTE: THE MAJORITY OF
THE INDIVIDUAL GFS AND ECMWF ENSEMBLE MEMBERS SHOW MEASURABLE
PRECIPITATION NEXT FRIDAY AND SATURDAY. -PETRUCELLI
AVIATION...FOR THE 31/00Z TAF CYCLE...ALONG THE COAST, LIGHT RAIN
WILL RESULT IN MVFR CIGS AND LOCAL IFR CIGS TONIGHT. CEILINGS SHOULD
IMPROVE TO VFR AROUND 18Z, BUT CONFIDENCE ON THE TIMING IS LOW TO
MEDIUM.
INLAND WEST SIDE. MVFR AND OCCASIONAL IFR CEILINGS WITH OCCASIONAL
REDUCTION OF VISIBILITY IS EXPECTED THROUGH THIS EVENING AS
STRATIFORM PRECIPITATION CONTINUE. THE GENERAL CONSENSUS IS FOR RAIN
TO DECREASE AND END TONIGHT, BUT PLENTY OF LOW LEVEL MOISTURE AND
STABLE CONDITIONS COULD RESULT IN MVFR AND OCCASIONAL IFR CEILINGS
NORTH OF THE UMPQUA DIVIDE AND AND POSSIBLY THE ILLINOIS AND ROGUE
VALLEY, INCLUDING MEDFORD. CONFIDENCE OF LOWER CEILINGS IN MEDFORD
WAS NOT HIGH ENOUGH TO INCLUDE IN THE TAF, SO LATER SHIFTS WILL NEED
TO TAKE ANOTHER LOOK AT THIS.
EAST OF THE CASCADES, MODERATE TO STRONG WINDS ARE POSSIBLE NORTH
AND EAST OF KLAMATH FALLS INTO THIS EVENING. KLAMATH FALLS AIRPORT
ARE NOT EXPECTED TO HAVE GUSTY WINDS. VFR CEILINGS ARE EXPECTED
TONIGHT, BUT WITH MOUNTAINS WILL BE PARTLY OBSCURED. MVFR CEILINGS
ARE POSSIBLE LATE TONIGHT AND THEY WERE ADDED TO THE TAF.
THE THREAT FOR THUNDERSTORMS HAVE MOVED NORTH OF THE AREA, BUT WE'LL
STILL NEED TO MONITOR ANY THUNDER THREAT INTO THIS EVENING.
-PETRUCELLI
MARINE...UPDATED 200 PM PDT SATURDAY 30 MAY 2020...A LOW MOVING
UP FROM THE SOUTH WILL SHIFT NORTHEASTWARD TONIGHT. SHOWERS WILL
DIMINISH LATE THIS EVENING AND TONIGHT. SEAS WILL BE DOMINATED BY
WEST SWELL THROUGH SUNDAY MORNING. GUSTY NORTH WINDS AND STEEP,
SHORT PERIOD SEAS WILL DEVELOP ACROSS THE WATERS SUNDAY AFTERNOON
AND EVENING THEN CONTINUE INTO EARLY NEXT WEEK. STRONG NORTH WINDS
AND VERY STEEP SEAS MAY DEVELOP FOR AREAS SOUTH OF PORT ORFORD
MONDAY AFTERNOON THROUGH TUESDAY. THEN GUSTY NORTH WINDS AND STEEP
SEAS ARE EXPECTED TO CONTINUE THROUGH AT LEAST MID WEEK. -CC
FIRE WEATHER...UPDATED 220 PM PDT SATURDAY, 30 MAY 2020...883 CLOUD
TO GROUND LIGHTNING FLASHES HAVE BEEN OBSERVED SINCE EARLY THIS
MORNING ACROSS THE FORECAST AREA. LIGHTNING PRODUCTION HAS SHARPLY
DIMINISHED OVER THE PAST FEW HOURS AS STABILITY INCREASES FROM WEST
TO EAST. THE AREA OF HEAVIER RAIN WILL CONTINUE THROUGH THE
AFTERNOON WEST OF THE CASCADES AND THEN DIMINISH, LEAVING MANY 1-
INCH RAINFALL TOTALS IN ITS WAKE. FROM THE CASCADES EASTWARD, RAIN
WILL MOVE OVERHEAD AS THE LOW OPENS UP AND MOVES NORTHEAST
OVERNIGHT. MUCH LIGHTER AMOUNTS ARE EXPECTED EAST OF THE CASCADES
COMPARED TO WEST OF THE CASCADES.
THE CONDITIONS THAT FOLLOW THE LIGHTNING ARE SO IMPORTANT, AND THE
TRENDS FOR SUNDAY ARE CLEARLY WARMER AND DRIER THAN TODAY, AND A
WARMING AND DRYING TREND SHOULD CONTINUE THROUGH WEDNESDAY.
TEMPERATURES SHOULD PEAK WEDNESDAY AT ABOUT 10 DEGREES ABOVE NORMAL,
AND THIS IS ABOUT 10 DEGREES COOLER THAN THE HOT TEMPERATURES THAT
WERE OBSERVED IN RECENT DAYS. AFTERNOON BREEZES TOMORROW SHOULD BE
LOWER THAN NORMAL, BUT WINDS WILL INCREASE SOME AHEAD OF THE NEXT
UPPER TROUGH. THE DRIEST AND BREEZIEST DAYS LOOK TO BE TUESDAY AND
WEDNESDAY BEFORE ANOTHER SYSTEM BRINGS COOLER CONDITIONS AND MORE
POTENTIAL FOR RAIN AND POSSIBLY THUNDERSTORMS LATE WEEK INTO THE
WEEKEND. CONFIDENCE IS MODERATE AT THIS TIME FOR THIS RETURN TO
COOLER AND WETTER CONDITIONS. KEENE
MFR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FROM 11 AM SUNDAY TO 5 AM PDT WEDNESDAY FOR
PZZ350-356-370-376.
HAZARDOUS SEAS WATCH FROM MONDAY MORNING THROUGH LATE TUESDAY
NIGHT FOR PZZ356-376.
SBN/SBN/SBN
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