922  
FXUS66 KMFR 210526  
AFDMFR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MEDFORD OR  
926 PM PST MON JAN 20 2025  
   
..UPDATED AVIATION DISCUSSION FOR 06Z TAFS  
 
   
DISCUSSION  
 
CLEAR SKIES HAVE DEVELOPED THIS AFTERNOON AS TEMPERATURES HAVE  
SHOT THROUGH THE 30'S AND ARE CURRENTLY IN THE UPPER 40'S IN MOST  
OF THE VALLEYS WEST OF THE CASCADES. CLOSER TO THE COAST, HIGHS  
ARE IN THE UPPER 50'S WITH SOME LIGHT NORTH EAST TO EAST FLOW AT  
4500 FEET. SOME HIGHER CLOUDS ARE STARTING TO SHUFFLE INTO THE  
FORECAST AREA, AND THEY SHOULD BECOME MORE WIDESPREAD LATER  
TONIGHT BASED ON CLOUD COVER FROM THE HREF MODEL.  
 
BY LATER TONIGHT, WE'LL LIKELY SEE MORE VALLEY STRATUS AND  
FREEZING FOG IN THE VALLEYS. THE MET AND MAV GUIDANCE IS  
PREDICTING FOG, AND LOW TEMPERATURES WILL BE WELL BELOW FREEZING  
IN MANY OF THE VALLEYS TONIGHT. THE HIGH CLOUDS COULD THROW A  
WRENCH IN THINGS, ALTHOUGH WE'RE THINKING THAT THE DRY LAYER AND  
INVERSION STRENGTH SHOULD USHER IN PLENTY OF FOG.  
 
BY TUESDAY, MID AND LOW LEVEL FLOW BECOMES ONSHORE WITH LIGHT  
WESTERLY WINDS. NO BIG PATTERN CHANGES AS HIGH PRESSURE REMAINS IN  
CONTROL, ALTHOUGH THE DIFFERENT WIND DIRECTION COULD PUSH SOME  
LOWER STRATUS INTO THE COAST TUESDAY AFTERNOON AND EVENING.  
 
HIGH PRESSURE WILL STRENGTHEN INTO WEDNESDAY WITH THE 500 MB  
RIDGE CENTERED RIGHT OVER SOUTHERN OREGON AND NORTHERN  
CALIFORNIA. THE END RESULT SHOULD BE PLENTY OF FREEZING FOG, SOME  
OF IT BEING VERY THICK AND UNDER 1/4 A MILE GIVEN THE STRENGTH OF  
SURFACE HIGH.  
 
FINALLY, THE WEATHER WILL CHANGE AROUND THURSDAY WHEN THE MAJORITY  
OF MODELS ARE PREDICTING AN UPPER LEVEL TROUGH AND COLD FRONT TO  
PUSH THROUGH THE FORECAST AREA. THE END RESULT WILL BE A 30 TO 40%  
CHANCE OF PRECIPITATION ACROSS THE MAJORITY OF THE FORECAST AREA  
WITH DRIER PROBABILITIES DOWN TO 0 TO 20 PERCENT FARTHER SOUTH.  
PRECIPITATION WILL LIKELY BE LIGHT AS NONE OF THE ENSEMBLE MEMBERS  
ARE PREDICTING MORE THAN 0.3 INCHES THROUGH THIS FRIDAY EVENT.  
HIGH PRESSURE WILL SETTLE BACK IN THIS WEEKEND.  
 
-SMITH  
 
 
   
AVIATION...21/06Z TAFS  
VFR LEVELS CONTINUE ACROSS NORTHERN  
CALIFORNIA AND SOUTHERN OREGON THIS EVENING. GUIDANCE STILL SHOWS  
SLIGHT CHANCES OF FOG DEVELOPING IN THE UMPQUA VALLEY TONIGHT,  
ALTHOUGH THOSE OUTCOMES ARE DISORGANIZED AND DO NOT COMMUNICATE  
DENSE, PERSISTENT FOG. DEVELOPMENT OF PATCHY FOG IS NOT IMPOSSIBLE  
IN THE ROGUE VALLEY, BUT DRIER AIR LIMITS THOSE CHANCES ENOUGH THAT  
FOG IS NOT INCLUDED FOR MEDFORD.  
 
OTHER AREAS LOOK TO REMAIN AT VFR THROUGH THIS TAF PERIOD. -TAD  
 
 
   
MARINE...UPDATED 930 PM MONDAY, JANUARY 20, 2025  
BELOW ADVISORY  
CONDITIONS PRESENT TONIGHT LOOK TO CONTINUE INTO TUESDAY WITH WEST-  
NORTHWEST SWELL DOMINATED SEAS REACHING A MINIMUM AT AROUND 5 TO 6  
FT AT 14 SECONDS.  
 
THE THERMAL TROUGH IS EXPECTED TO STRENGTHEN AGAIN WEDNESDAY WITH  
SEAS LIKELY BECOMING STEEP, AT LEAST FOR THE OUTER WATERS SOUTH OF  
CAPE BLANCO. THERE'S GOOD AGREEMENT FOR MODERATE TO STRONG NORTH  
WINDS LATER IN THE WEEK WITH A STRONG THERMAL TROUGH DEVELOPING  
ALONG THE COAST. WINDS ARE LIKELY TO REACH LOW END GALES WITH STEEP  
TO VERY STEEP SEAS. -PETRUCELLI  
 
 
   
MFR WATCHES/WARNINGS/ADVISORIES  
 
OR...AIR STAGNATION ADVISORY UNTIL 10 AM PST TUESDAY FOR ORZ021-  
023>026-029>031.  
 
BEACH HAZARDS STATEMENT UNTIL 4 PM PST THIS AFTERNOON FOR ORZ021-  
022.  
 
CA...NONE.  
 
PACIFIC COASTAL WATERS...BEACH HAZARDS STATEMENT UNTIL 4 PM PST THIS  
AFTERNOON FOR PZZ350-356.  
 
 
 
 
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