880  
FXUS66 KMFR 272158  
AFDMFR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MEDFORD OR  
258 PM PDT SAT MAY 27 2023  
   
SHORT TERM  
TONIGHT (5/27) THROUGH MONDAY NIGHT  
(5/29)...CURRENT RADAR IS SHOWING SCATTERED TO NUMEROUS SHOWERS  
AND THUNDERSTORMS ACROSS SOUTHERN OREGON AND NORTHERN CALIFORNIA.  
WHILE MOST OF THE SHOWERS AND STORMS ARE INDEED ALONG AND EAST OF  
THE CASCADES AND IN ALL OF NORTHERN CALIFORNIA, A COUPLE OF  
THUNDERSTORMS JUST DEVELOPED IN JOSEPHINE COUNTY, SUGGESTING THAT  
THINGS ARE A LITTLE MORE WIDESPREAD THAN WE ANTICIPATED. WILL HAVE  
TO CONTINUE TO MONITOR THESE STORMS. IN PARTICULAR, MODOC COUNTY  
HAS SEEN QUITE A BIT OF LIGHTNING ALREADY WITH THESE STORMS. ALSO,  
IT IS WORTH NOTING THAT THESE STORMS ARE RELATIVELY SLOW MOVING.  
SHOULD THE STORMS FORM INTO A CLUSTER OR TRAIN (MOVE OVER THE SAME  
AREA ONE RIGHT AFTER THE OTHER), PONDING OF WATER WILL BE  
POSSIBLE, ESPECIALLY IN STEEP IN COMPLEX TERRAIN. HOWEVER, SEVERE  
WEATHER IS NOT ANTICIPATED; BUT THAT WILL NOT NATURALLY SUPPRESS  
CELLS THAT OVERACHIEVE.  
 
TODAY IS THE BIG THUNDERSTORM DAY AS FAR AS THE REST OF THE WEEK  
IS CONCERNED. HOWEVER THUNDERSTORMS WILL CONTINUE FOR THE NEXT  
SEVERAL DAYS AS AN AREA OF LOW PRESSURE MOVES SOUTHWARD OVER OUR  
AREA. THUNDERSTORMS WILL LARGELY STAY ALONG AND EAST OF THE  
CASCADES--ALTHOUGH THAT LINE OF THOUGHT IS NOT QUITE WORKING OUT  
TODAY.  
 
TEMPERATURES WILL BE ABOVE NORMAL, BUT NOT HOT. WE STILL ARE  
EXPECTING MILD TEMPERATURES THROUGHOUT THE HOLIDAY.  
   
LONG TERM  
TUESDAY 12Z UNTIL SATURDAY 12Z.  
 
A BROAD UPPER LEVEL WAVE WILL BEGIN TO DIG INTO THE PACIFIC  
NORTHWEST LATER ON TUESDAY EVENING. NORTH WESTERLY FLOW WILL  
CONTINUE TO MOVE INTO THE FORECAST AREA ALLOWING FOR SOME SLIGHTLY  
COOLER AIR TO SHUFFLE ON IN. TEMPERATURES ARE ANTICIPATED TO REMAIN  
NEAR NORMAL OR SLIGHTLY ABOVE NORMAL INTO NEXT WEEK. THE NBM TRENDS  
TEMPERATURES COOLER BY ABOUT 5 TO 8 DEGREES ON WEDNESDAY AS A COLD  
FRONT AND THE UPPER LEVEL WAVE LIKELY MOVE THROUGH. A PERSISTENT  
THUNDERSTORM THEME WILL REMAIN IN PLACE FOR NEXT WEEK. THE AREA OF  
CONCERN REMAINS IN NORTHERN AND NORTHEASTERN CALIFORNIA. IT SEEMS  
THIS IS THE MOST LIKELY SPOT AS THE CONVECTIVE INHIBITION IS LOWER  
IN THIS AREA AND POTENTIAL INSTABILITY IS NOTABLY HIGHER.  
 
BY THURSDAY INTO FRIDAY, TEMPERATURES BEGIN TO TAKE A TREND HIGHER  
WITH THE PROBABILITY OF THUNDERSTORMS TRENDING LOWER(10-20%) OVER  
NORTHERN CALIFORNIA. MODELS BEGIN TO DIVERGE ON SOME OF THE  
SYNOPTIC DETAILS, SO THESE PROBABILITIES WILL LIKELY CHANGE AS WE  
MOVE INTO NEXT WEEK.  
 
BY NEXT WEEKEND, ENSEMBLES SEEM MORE CONFIDENT IN HIGH PRESSURE  
BUILDING OVER THE FORECAST AREA. HIGHS ARE ANTICIPATED IN UPPER TO  
MID 80'S WITHIN THE WESTSIDE VALLEYS AND UPPER 70'S EAST OF THE  
CASCADES.  
 
OVERALL, PRETTY NORMAL WEATHER FOR THIS TIME OF YEAR AS NOTHING  
STANDS OUT AS EXTREME IN THE ENSEMBLE TOOL SETS. THE ONLY WEATHER  
THREAT WILL BE THE CONTINUED THREAT OF LIGHTNING OVER SPARSELY  
POPULATED AREAS.  
 
-SMITH  
 
 
   
AVIATION...27/18Z TAFS  
A MARINE LAYER REMAINS IN PLACE ALONG  
THE OREGON COAST, BRINGING LIFR/IFR CEILINGS AND FLUCTUATING  
VISIBILITIES WITH SOME OCCASIONAL LIGHT RAINFALL. INLAND AREAS ARE  
CURRENTLY UNDER VFR CONDITIONS WITH VARIABLE WINDS.  
 
THE MARINE LAYER WILL REMAIN IN PLACE THROUGH THE TAF PERIOD, AND IS  
EXPECTED TO BRING A BRIEF PERIOD OF MVFR CEILINGS INTO THE UMPQUA  
VALLEY THIS MORNING. ALONG THE COAST, VISIBILITIES WILL CLEAR LATER  
THIS MORNING AND CEILINGS MAY RAISE TO MVFR THIS AFTERNOON BEFORE  
DROPPING BACK TO IFR/LIFR THIS EVENING INTO SUNDAY MORNING. LOOKING  
INLAND, SLIGHT CHANCES OF THUNDERSTORMS WILL RETURN TO NORTHERN  
CALIFORNIA AND AREAS EAST OF THE CASCADES THIS AFTERNOON AND WILL  
GRADUALLY DISSIPATE AFTER SUNSET. -TAD/HERMANSEN  
 
 
   
MARINE...UPDATED 200 PM PDT SATURDAY, MAY 27  
GUSTY NORTH  
WINDS AND STEEP SEAS WILL RESUME TODAY ACROSS ALL WATERS, WITH THE  
STRONGEST WINDS AND STEEPEST SEAS SOUTH OF CAPE BLANCO. NORTH WINDS  
WILL INCREASE FURTHER SUNDAY MORNING, BRINGING PERIODS OF VERY STEEP  
HAZARDOUS SEAS SOUTH OF GOLD BEACH. LOCALIZED AREAS OF GALE WINDS  
ARE ALSO POSSIBLE IN THIS AREA. NORTHERLY WINDS AND STEEP SEAS ARE  
EXPECTED TO CONTINUE INTO MIDWEEK. -TAD/HERMANSEN  
 
 
   
MFR WATCHES/WARNINGS/ADVISORIES  
 
OR...CA...NONE.  
 
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 5 PM PDT MONDAY  
FOR PZZ350-356-370-376.  
 
HAZARDOUS SEAS WARNING FROM 11 AM SUNDAY TO 5 PM PDT MONDAY FOR  
PZZ356-376.  
 
 
 
 
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