620
FXUS66 KMFR 230942
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
242 AM PDT THU JUL 23 2026
KEY MESSAGES
*A MUCH DRIER AIR MASS MOVES INTO THE AREA TODAY AND WILL PERSIST
FOR AT LEAST THE NEXT 7 DAYS.
*OVERALL, TEMPERATURES WILL BE VERY WARM, BUT SHOULD BE PRETTY
CLOSE TO OR JUST SLIGHTLY ABOVE NORMAL FOR LATE JULY.
*OTHER THAN DAILY INTRUSIONS OF MARINE STRATUS ALONG THE COAST
(AND PERHAPS A SLIGHT CHANCE OF DRIZZLE AT TIMES), CLOUD COVER
WILL BE MINIMAL AND PRECIP CHANCES WILL BE NEAR ZERO FOR INLAND
AREAS.
*LITTLE TO NO RISK FOR THUNDERSTORMS DURING THIS TIME PERIOD, BUT
THERE WILL BE PERIODS OF STRONG, GUSTY WINDS AND ALSO VERY LOW
HUMIDITY. THESE TWO ELEMENTS WILL OVERLAP AT TIMES DURING THE
AFTERNOONS/EVENINGS CAUSING CRITICAL FIRE WEATHER CONDITIONS.
THIS IS MOST LIKELY FRIDAY AND SATURDAY FOR PORTIONS OF NORTHERN
CALIFORNIA AND ALSO AREAS EAST OF THE CASCADES.
DISCUSSION
LOW PRESSURE OFFSHORE THIS MORNING WILL GRADUALLY
EJECT TOWARD THE NORTHEAST OVER THE NEXT 24-48 HOURS WHILE UPPER
RIDGING PERSISTS NEAR THE ROCKIES. THE FLOW ALOFT, WHICH HAD BEEN
SOUTHERLY DURING THE PAST FEW DAYS, IS TURNING SOUTHWESTERLY, AND
THIS IS ALLOWING A MUCH DRIER AIR MASS TO MOVE IN. AS SUCH, THE
RISK OF THUNDERSTORMS TODAY IS NEAR ZERO WITH ANY CONVECTIVE
ACTIVITY OCCURRING WELL TO THE NORTH AND EAST OF THE MEDFORD CWA.
TEMPERATURES WERE HOT YESTERDAY HERE IN THE VALLEY DUE TO STRONG
DOWNWARD TRANSPORT (MIXING DOWN FROM 12000 FEET AGL!) DURING THE
AFTERNOON -- WE MANAGED TO HIT 105F AT THE AIRPORT, WHICH WAS ONLY
ONE DEGREE SHY OF THE RECORD (106F SET IN 2006/1928). OTHER AREAS
DIDN'T SEE THE DEGREE OF MIXING THAT WE SAW HERE IN THE ROGUE
VALLEY, SO TEMPS DIDN'T GET SO HOT -- HIGHS OF ONLY 87F IN MOUNT
SHASTA CITY, 90F IN KLAMATH FALLS, 93F IN ROSEBURG, AND 94F IN
BOTH MONTAGUE AND ALTURAS. EXPECT TEMPS TO BE A BIT COOLER TODAY
COMPARED TO YESTERDAY HERE IN MEDFORD (HIGH OF 96F), BUT SIMILAR
READINGS COMPARED TO YESTERDAY ELSEWHERE. MARINE CLOUDS SHOULD
PEEL BACK TO THE BEACHES, BUT MAY PERSIST ALONG THE IMMEDIATE
COAST THIS AFTERNOON, THEN RETURN TO AREAS JUST INLAND TONIGHT.
AS THE LOW EJECTS TO THE NE, MID-LEVEL SW FLOW WILL INCREASE
ACROSS THE CWA. SO, BY FRIDAY AFTERNOON AND EVENING, A WELL-
MIXED BOUNDARY LAYER WILL TRANSPORT SOME OF THOSE STRONGER WINDS
ALOFT DOWN TO THE SURFACE, ESPECIALLY EAST OF THE CASCADES, BUT
ALSO IN NORTHERN CALIFORNIA. EXPECT WIDESPREAD SW-W WINDS OF 10-20
MPH WITH PEAK GUSTS OF 30-40 MPH. AT THE SAME TIME, THE SURFACE
DEWPOINTS WILL CRASH RESULTING IN VERY LOW HUMIDITY, IN SOME
CASES, AS LOW AS 5-10% OVER THE FAR EAST SIDE. THIS WILL BRING
CRITICAL FIRE WEATHER CONDITIONS AND FIRE WEATHER WATCHES ARE IN
EFFECT. THIS PATTERN WILL PERSIST INTO SATURDAY WITH A GRADUAL
SHIFT EASTWARD AND SOUTHWARD OF THE MAIN CORE OF OVERLAPPING GUSTY
WINDS/LOW RH. A SMALLER AREA OF CRITICAL FIRE CONDITIONS COULD
LINGER SUNDAY PM/EVE OVER MODOC AND PORTIONS OF SE KLAMATH/LAKE
COUNTIES.
A BROAD UPPER TROUGH IS FORECAST TO PERSIST OFF THE BRITISH
COLUMBIA COAST OR IN THE GULF OF ALASKA NEXT WEEK WITH THE UPPER
RIDGE REMAINING OVER THE INTERMOUNTAIN WEST/FOUR CORNERS. THIS
PATTERN SHOULD ALLOW WINDS TO RELAX A BIT EARLY NEXT WEEK, BUT IT
WILL REMAIN DRY AS ANY MONSOONAL MOISTURE WILL REMAIN CUT OFF FROM
THE AREA (SHUNTED TO THE SOUTHEAST BY PREVAILING SW FLOW ALOFT).
TEMPERATURES OVERALL SHOULD BE WITHIN A FEW DEGREES EITHER SIDE OF
NORMAL, A BIT LOWER (COOLER) THOUGH NEARER THE COAST WHERE DAILY
MARINE INTRUSIONS BRING MORE CLOUD COVER. -SPILDE
AVIATION...23/12Z TAFS
VFR PREVAILS ACROSS MOST OF THE CWA FOR
THE NEXT 24 HOURS. THIS INCLUDES MEDFORD AND KLAMATH FALLS. SOME
CLOUD COVER IS PRESENT THIS MORNING WHERE THUNDERSTORMS OCCURRED IN
THE CASCADE FOOTHILLS YESTERDAY (NEAR AND NORTH OF CRATER LAKE).
MARINE STRATUS (MOSTLY MVFR, BUT LOCAL IFR) IS ALSO PRESENT ALONG
THE COAST. THINK THIS WILL PEEL BACK TO AROUND THE BEACHES THIS
AFTERNOON, SO THERE MAY BE SOME VFR AT TIMES THEN, BUT EXPECT THE
MVFR/IFR TO RETURN TONIGHT. ROSEBURG IS TRICKY THIS MORNING. COULD
SEE BRIEF MVFR THIS MORNING, BUT SHOULD BECOME VFR BY THIS
AFTERNOON. LOCAL MVFR COULD RETURN TO ROSEBURG LATE TONIGHT.
-SPILDE
MARINE...UPDATED 230 AM PDT THURSDAY, JULY 23, 2026
A BRIEF PERIOD
OF STRONGER SOUTH WINDS AND STEEP SEAS, MAINLY IN WATERS BEYOND
10 NM FROM SHORE, IS EXPECTED THIS MORNING. OTHERWISE, MIXED SEAS
WITH FRESH SHORT PERIOD NORTHWEST SWELL AND LOW LONGER PERIOD
SOUTH SWELL ARE EXPECTED THROUGH FRIDAY. SOUTH WINDS SWITCH BACK
TO NORTHERLY THIS WEEKEND, BUT WIND WAVE DOMINATED SEAS PROBABLY
HOLD OFF UNTIL EARLY NEXT WEEK. -SPILDE/BPN
FIRE WEATHER...UPDATED 230 AM PDT THURSDAY, JULY 23, 2026
A SHIFT IN THE UPPER LEVEL PATTERN IS EXPECTED TODAY, WHICH WILL
MOVE THE REGION OF INSTABILITY/CONVECTIVE ACTIVITY WELL TO THE
NORTH AND EAST OF OUR AREA WITH DRIER SW FLOW ALOFT WINNING OUT.
AS SUCH, LIGHTNING RISK WILL DIMINISH TO NIL TODAY, BUT AT THE
EXPENSE OF ENHANCED SOUTHWEST TO WESTERLY WINDS DURING THE
AFTERNOONS AND EVENINGS EAST OF THE CASCADES AND IN NORTHERN
CALIFORNIA. THIS IS LIKELY TO OVERLAP WITH LOW HUMIDITY,
ESPECIALLY ON FRIDAY AND SATURDAY. ANY NEW FIRE STARTS WOULD THEN
HAVE THE ABILITY TO SPREAD/GROW QUICKLY. FIRE WEATHER WATCHES
REMAIN IN PLACE FOR FRIDAY AND SATURDAY AFTERNOONS/EVENINGS IN
FWZS 624, 625, 284, AND 285. WE'VE ALSO ADDED FWZS 280 AND 281 FOR
FRIDAY AFTERNOON/EVENING AS THERE SHOULD BE A SEVERAL HOUR PERIOD
OF GUSTY WINDS/LOW RH FOR THOSE AREAS AS WELL. CONDITIONS WILL
EASE DURING THE OVERNIGHT PERIOD, WITH GENERALLY POOR TO MODERATE
RECOVERIES, POOREST ALONG THE WARNERS OF MODOC COUNTY.
THE DRY, DIURNALLY BREEZY PATTERN LOOKS TO LAST THIS WEEKEND AND
INTO EARLY NEXT WEEK. BUT, WINDS SHOULD EASE SOME AND TEMPERATURES
SHOULD ALSO LOWER COMPARED TO EARLIER THIS WEEK. -SPILDE
MFR WATCHES/WARNINGS/ADVISORIES
OR...FIRE WEATHER WATCH FROM FRIDAY AFTERNOON THROUGH SATURDAY
EVENING FOR ORZ624-625.
CA...FIRE WEATHER WATCH FROM FRIDAY AFTERNOON THROUGH FRIDAY
EVENING FOR CAZ280-281.
FIRE WEATHER WATCH FROM FRIDAY AFTERNOON THROUGH SATURDAY
EVENING FOR CAZ284-285.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 11 AM PDT THIS
MORNING FOR PZZ370-376.
MAS
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