583
FXUS66 KMFR 221023
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
323 AM PDT WED JUL 22 2026
KEY MESSAGES
* LAST DAY OF THE HUMID PATTERN WITH MOIST, SOUTHERLY MONSOONAL
FLOW AND ISOLATED TO SCATTERED THUNDERSTORMS. THE HIGHEST RISK
OF SCATTERED THUNDERSTORMS TODAY WILL BE FROM THE FOOTHILLS OF
THE CASCADES IN EASTERN DOUGLAS COUNTY ACROSS THE CASCADES, INTO
NORTHERN KLAMATH AND LAKE COUNTIES. SOME STORMS WILL BE STRONG
WITH GUSTY WINDS AND POSSIBLE HAIL.
* TODAY WILL BE THE HOTTEST OF THE NEXT SEVERAL DAYS WITH HIGHS
GENERALLY 5 TO 10 DEGREES ABOVE NORMAL (MID 80S TO MID 90S ON
THE EAST SIDE AND LOWER 90S TO 104 FOR WEST SIDE VALLEYS). NEAR
OR SLIGHTLY BELOW NORMAL TEMPERATURES AT THE COAST WILL REACH
THE 60S.
* A DRY PATTERN TAKES HOLD THURSDAY INTO THE WEEKEND. BUT AN
INCREASE IN AFTERNOON/EVENING SOUTHWEST TO WEST WINDS IS LIKELY,
ESPECIALLY EAST OF THE CASCADES AND IN NE CALIFORNIA WHERE WINDS
OVERLAP VERY LOW HUMIDITY RESULTING IN CRITICAL FIRE WEATHER
CONDITIONS.
DISCUSSION
THE AREA HAS BEEN WEDGED IN BETWEEN STRONG UPPER
RIDGING OVER THE NATION'S MIDSECTION AND LOW PRESSURE OFF THE WEST
COAST FOR THE LAST SEVERAL DAYS. THIS HAS BROUGHT A PLUME OF VERY
MOIST, MONSOONAL MOISTURE NORTHWARD INTO THE AREA, AND IT HAS
FELT MORE HUMID THAN USUAL. THIS WILL CONTINUE TO BE THE CASE
TODAY WITH DEWPOINTS EXPECTED TO BE IN THE UPPER 50S TO EVEN MID
60S WEST OF THE CASCADES. HIGH TEMPERATURES WILL ONCE AGAIN BE IN
THE 90S AND EVEN LOWER 100S. IN THIS TYPE OF PATTERN, WE'D
USUALLY EXPECT DAILY OUTBREAKS OF THUNDERSTORMS. BUT, THIS HAS
BEEN MUTED SO FAR WITH JUST ISOLATED ACTIVITY, MAINLY DUE TO A
LACK OF FORCING AND HIGH CLOUD COVER ULTIMATELY REDUCING
INSTABILITY. THIS SHOULD CHANGE SOMEWHAT TODAY AS INSTABILITY
INCREASES ACROSS THE AREA AND WITH THE LOW OFFSHORE MOVING
NORTHWARD (ALONG WITH THE REMNANTS OF ELIDA), FORCING FOR ASCENT
SHOULD BE ENHANCED NEAR THE CASCADES IN DIFFLUENT FLOW ALOFT. IT
WILL BE A RACE THOUGH, SO TO SPEAK, SINCE MODELS ARE SHOWING DRIER
AIR ALOFT ARRIVING FROM THE SOUTH AND WEST LATER TODAY AND
TONIGHT. AS SUCH, WE THINK THE FOCUS FOR CONVECTION THIS
AFTERNOON/EVENING WILL BE FROM THE CASCADE FOOTHILLS OF EASTERN
DOUGLAS COUNTY ACROSS THE CASCADES TO NORTHERN KLAMATH AND LAKE
COUNTIES. CONVECTION ALLOWING MODELS SHOW THIS AREA STANDS A GOOD
CHANCE AT GETTING SOME CELLS WITH FREQUENT LIGHTNING. THEY'LL
MOVE QUICKLY AT AROUND 20-25 MPH TO THE NNE. WITH A VERY DRY
LANDSCAPE, THIS PRESENTS CRITICAL FIRE WEATHER RISK, SO WE HAVE A
RED FLAG WARNING OUT FOR THAT. STORMS THAT DO DEVELOP COULD ALSO
HAVE STRONG OUTFLOW WIND GUSTS (INVERTED-V SOUNDINGS INDICATE
POTENTIAL NEAR OR JUST SUB-SEVERE GUSTS), HAIL AND BRIEF HEAVY
RAINFALL. WHILE WE CAN'T RULE OUT ISOLATED ACTIVITY FARTHER SOUTH
AND WEST, AGAIN, THE LIMITING FACTOR WILL BE THE DRIER AIR MOVING
IN ALOFT. EXPECT SOME BREEZY WINDS TO DEVELOP JUST ABOUT
EVERYWHERE THIS AFTERNOON/EVENING.
ONCE WE GET RID OF THE CONVECTION THIS EVENING, THAT WILL BE IT
FOR A WHILE. A RE-ORIENTATION OF THE FLOW ALOFT TO THE SOUTHWEST
WILL BRING IN A MUCH DRIER PATTERN. MODELS ARE SHOWING A STRONG
MID-LEVEL 500 MB JET OF 45-55 KT DEVELOPING FRI/SAT. THIS IS
GOING TO CAUSE BREEZY TO WINDY CONDITIONS AREA WIDE, STRONGEST
EAST OF THE CASCADES AND IN NE CALIFORNIA. AT THE SAME TIME,
MASSIVE DRYING WILL BRING DEWPOINTS WAY DOWN RESULTING IN VERY LOW
HUMIDITY, IN SOME CASES, DOWN BELOW 10% OVER MODOC/LAKE COUNTIES.
SINCE THERE IS HIGH CONFIDENCE IN THIS PATTERN OF OVERLAPPING
STRONG, GUSTY WINDS AND LOW RELATIVE HUMIDITY, WE'VE GONE AHEAD
AND ISSUED A FIRE WEATHER WATCH FOR BOTH FRI/SAT PM/EVE EAST OF
THE CASCADES AND IN NE CALIFORNIA. THESE CONDITIONS COULD PERSIST
INTO SUNDAY. TEMPERATURES, MEANWHILE, SHOULD MODERATE A BIT --
THEY WON'T BE QUITE AS HOT AS THEY ARE TODAY.
MONSOONAL MOISTURE SHOULD REMAIN WELL TO THE SOUTH AND EAST OF OUR
AREA INTO NEXT WEEK DUE TO PERSISTENT SOUTHWEST FLOW ALOFT, PRETTY
TYPICAL FOR LATE JULY. -SPILDE
AVIATION...22/12Z TAFS
MOSTLY VFR IS PRESENT ACROSS NORTHERN
CALIFORNIA AND SOUTHERN OREGON EARLY THIS MORNING.
MARINE STRATUS IS BRINGING IFR/LIFR AT THE COAST NORTH OF CAPE
BLANCO THIS MORNING. IMPROVEMENT WILL FOLLOW FOR THE AFTERNOON
INTO EARLY EVENING, WITH THESE LEVELS EXPECTED TO LIFT TO MVFR
NORTH OF CAPE BLANCO. HOWEVER, WE EXPECT ONSHORE FLOW TO COMMENCE
SOUTH OF THE CAPE, SO WHILE IT'S VFR THERE NOW, A SURGE OF LOW
STRATUS COULD RESULT IN IFR THERE LATER THIS MORNING OR THIS
AFTERNOON.
THUNDERSTORMS ARE EXPECTED THIS AFTERNOON, ESPECIALLY OVER
EASTERN DOUGLAS COUNTY AS WELL AS LAKE AND NORTHERN KLAMATH
COUNTIES. ACTIVITY MAY ALSO DEVELOP IN JACKSON, AND SOUTHERN
KLAMATH, AND WESTERN SISKIYOU COUNTIES. THESE STORMS MAY BE STRONG
ENOUGH TO DEVELOP SMALL HAIL, LIGHTNING, LOCALLY HEAVY RAIN, AND
GUSTY, ERRATIC WINDS. WHILE THE MOST AGGRESSIVE ACTIVITY IS
CURRENTLY EXPECTED TO MOSTLY STAY AWAY FROM AREA TERMINALS, NOTES
OF VICINITY ACTIVITY HAVE BEEN INCLUDED AT MEDFORD TO COMMUNICATE
THE POSSIBLE DEVELOPMENT OF THUNDERSTORM ACTIVITY. -SPILDE
MARINE...UPDATED 300 AM PDT WEDNESDAY, JULY 22, 2026
WINDS AND
SEAS ARE EXPECTED TO REMAIN BELOW ADVISORY LEVELS THROUGH AT
LEAST THIS WEEKEND. NORTH WINDS SWITCH TO SOUTHERLY TODAY AS THE
REMNANTS OF ELIDA MOVE NORTHWARD OFFSHORE. ISOLATED SHOWERS AND
EVEN A COUPLE OF THUNDERSTORMS ARE POSSIBLE. 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
FIRE WEATHER...UPDATED 300 AM PDT WEDNESDAY, JULY 22, 2026
TODAY, THERE IS A GREATER CONCERN FOR INCREASED AFTERNOON AND
EVENING THUNDERSTORM COVERAGE (AT LEAST IN NORTHERN PARTS OF THE
AREA) DUE TO BETTER INSTABILITY EXPECTED AND THE POTENTIAL FOR
BETTER FORCING AS THE REMNANTS OF ELIDA PUSH NORTHWARD JUST OFFSHORE
RESULTING IN DIFFLUENT FLOW ALOFT. WE THINK THE GREATEST ACTIVITY IN
TERMS OF COVERAGE WILL OCCUR ALONG THE WESTERN SLOPES OF THE
CASCADES (EASTERN FWZS 622/617) EAST ACROSS THE CASCADES (FWZ623),
AND THEN ALSO EAST OF THE CASCADES IN THE TYPICAL ARC FROM CRATER
LAKE, ACROSS WINTER RIM, AND DOWN TO THE WARNERS (FWZS 624/625).
ISOLATED STORMS ARE ALSO POSSIBLE ELSEWHERE ACROSS THE AREA,
INCLUDING IN NORTHERN CALIFORNIA AND ACROSS THE VALLEYS
WEST OF THE CASCADES, THOUGH A SURGE OF DRIER AIR ALOFT DOES APPEAR
TO BE PUSHING INTO NORCAL LATER IN THE AFTERNOON/EVENING (THIS
SHOULD KEEP BEST ACTIVITY CONFINED TO AREAS NORTH OF THE OR/CA
BORDER). STORMS THAT DO DEVELOP SHOULD BE MOVING AT A PRETTY GOOD
CLIP - IN THE 20-30 MPH RANGE, SO WHILE THEY ARE LIKELY TO BE WETTER
STORMS WITH HIGHER PWS, THE FASTER STORM MOTIONS SHOULD STILL RAISE
THE RISK OF LIGHTNING-INDUCED FIRE IGNITIONS AND A RED FLAG WARNING
IS IN EFFECT.
OF NOTE, WITH PW APPROACHING OR EXCEEDING 1.50 INCHES, OR ROUGHLY
200 PERCENT OF NORMAL, THESE STORMS SHOULD NOT ONLY BE WET, BUT
COULD PRODUCE HEAVY RAIN AS WELL. SHOULD A STORM PASS DIRECTLY OVER
A RECENT BURN, SUCH AS THE EAST EVANS CREEK FIRE, MUD AND DEBRIS
FLOWS ARE POSSIBLE DOWN ANY ADJACENT DRAINAGES.
LATER THIS WEEK (THURSDAY/FRIDAY), EASTWARD MOVEMENT IN THE UPPER
LEVEL PATTERN IS LIKELY, WHICH IS LIKELY TO SHIFT THE REGION OF
INSTABILITY EAST OF OUR AREA WITH DRIER SW FLOW ALOFT WINNING OUT.
AS SUCH, LIGHTNING RISK WILL DIMINISH TO ALMOST NIL, BUT AT THE
EXPENSE OF ENHANCED WESTERLY WINDS DURING THE AFTERNOONS AND
EVENINGS EAST OF THE CASCADES, WHICH COULD OVERLAP WITH LOW
HUMIDITY. ANY NEW FIRE STARTS WOULD THEN HAVE THE ABILITY TO
SPREAD/GROW QUICKLY. WE HAVE GONE AHEAD AND ISSUED A FIRE
WEATHER WATCH FOR FRIDAY AND SATURDAY AFTERNOONS/EVENINGS IN FWZS
624, 625, 284, AND 285.
THE DRY, DIURNALLY BREEZY PATTERN LOOKS TO LAST THIS WEEKEND AND
INTO EARLY NEXT WEEK. BUT, TEMPERATURES SHOULD ALSO LOWER SOME
COMPARED TO EARLIER THIS WEEK. -SPILDE/BPN
MFR WATCHES/WARNINGS/ADVISORIES
OR...FIRE WEATHER WATCH FROM FRIDAY AFTERNOON THROUGH SATURDAY
EVENING FOR ORZ624-625.
RED FLAG WARNING FROM 11 AM THIS MORNING TO 11 PM PDT THIS
EVENING FOR ORZ617-622>625.
CA...FIRE WEATHER WATCH FROM FRIDAY AFTERNOON THROUGH SATURDAY
EVENING FOR CAZ284-285.
PACIFIC COASTAL WATERS...NONE.
MAS
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