744
FXUS66 KMTR 191108
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
408 AM PDT TUE AUG 19 2025
..NEW AVIATION, MARINE
KEY MESSAGES
UPDATED AT 245 PM PDT MON AUG 18 2025
- WARMING TREND INTO THE WEEKEND
- MODERATE HEATRISK FOR THE INTERIOR THURSDAY-SATURDAY
- SEE HEAT SAFETY TIPS BELOW
SHORT TERM
ISSUED AT 108 AM PDT TUE AUG 19 2025
(TODAY AND TONIGHT)
SATELLITE SHOWS IT'S CLEAR EXCEPT FOR A PATCH OR TWO OF COASTAL
STRATUS AND FOG. EXCEPT FOR PATCHY COASTAL STRATUS AND FOG, A SUNNY
DAY IS FORECAST TODAY. FORECAST HIGHS TODAY WILL BE WITHIN A FEW
DEGREES OF NORMAL MID AUGUST HIGH TEMPERATURES, IN THE UPPER 60S
TO LOWER 70S NEAREST THE COAST AND BAYS AND AS WARM TO HOT AS THE
MID 80S TO LOWER 90S FARTHEST INLAND.
LONG TERM
ISSUED AT 108 AM PDT TUE AUG 19 2025
(WEDNESDAY THROUGH MONDAY)
A STRONG HIGH PRESSURE SYSTEM NEAR THE FOUR CORNERS WILL PLACE
OUR FORECAST AREA UNDER INCREASING 500 MB HIGH PRESSURE WITH
INCREASING 925-500 MB THERMAL RIDGING THROUGH MID TO LATE WEEK.
WIND FLOW IN THE LOWER ATMOSPHERE WILL BE TEMPORARILY NORTHERLY BY
MID WEEK AND THE MARINE LAYER WILL BECOME COMPRESSED TO NEAR SEA
LEVEL. HIGHS WILL WARM TO ABOVE NORMAL FOR LATE AUGUST SINCE 850
MB TEMPS WILL BE ABOVE THE 90TH PERCENTILE. FORECAST HIGHS IN THE
HOTTEST SPOTS FARTHEST INLAND E.G. MAY APPROACH 100F TO 102F. IN
GENERAL THE 500 MB PATTERN ACROSS THE SOUTHWEST U.S. AND CENTRAL/EASTERN
PACIFIC WILL BE STATIONARY TO SLIGHTLY RETROGRESSIVE, KEEPING OUR
FORECAST AREA UNDER THE WESTERN PORTION OF THE FOUR CORNERS 500 MB
HIGH PRESSURE SYSTEM.
HEAT SAFETY TIPS:
HEAT IS THE NUMBER 1 WEATHER RELATED KILLER IN THE UNITED STATES.
FOLLOW THESE TIPS TO PROTECT YOURSELF, YOUR LOVED ONES, AND YOUR
ANIMALS.
-STAY INSIDE IN AN AIR CONDITIONED ENVIRONMENT BETWEEN 10AM AND 7PM.
-SUSPEND UNNECESSARY OUTDOOR ACTIVITIES DURING MODERATE HEAT, BUT
IF YOU MUST BE OUTDOORS, TAKE FREQUENT BREAKS IN THE SHADE OR AC
AND DRINK COOL WATER.
-KNOW THE SIGNS AND SYMPTOMS OF HEAT EXHAUSTION VS. HEAT STROKE!
HEAT STROKE CAN BE DEADLY IF NOT TREATED IMMEDIATELY BY A MEDICAL
PROFESSIONAL. CALL 911 IF YOU SUSPECT SOMEONE IS SUFFERING FROM HEAT
STROKE.
-WEAR A LIFE JACKET, SWIM NEAR A LIFEGUARD, AND CHECK CONDITIONS
BEFORE ENTERING THE WATER IF GOING TO A RIVER OR OCEAN TO COOL OFF.
RIVERS AND THE OCEAN ARE EXTREMELY COLD, AND COLD WATER SHOCK CAN
TURN INTO PARALYSIS AND DROWNING IF YOU ARE NOT CAREFUL.
-USE A COOL AND DAMP TOWEL ON YOUR BODY IF YOU DO NOT HAVE AC AND
ARE FEELING HOT. OR, TAKE A COOL SHOWER OR BATH.
-DO NOT LEAVE KIDS OR PETS IN A PARKED CAR.
-ENSURE PETS AND LIVESTOCK HAVE ACCESS TO SHADE AND WATER.
AVIATION
(12Z TAFS)
ISSUED AT 407 AM PDT TUE AUG 19 2025
CURRENTLY VFR AT ALL TERMINALS WITH NOT A CLOUD IN THE SKY. THE FORT
ORD PROFILER SHOWS THE MARINE LAYER AT 800 FEET WITH
NORTHERLY/OFFSHORE FLOW ALOFT - HENCE THE CLEAR SKIES. AS THE FOUR
CORNERS HIGH PRESSURE CONTINUES TO NUDGE INTO THE REGION, WARMER AND
DRIER AIR WILL FOLLOW SUIT. THE MARINE LAYER WILL REMAIN
COMPRESSED/SHALLOW, WITH FURTHER COMPRESSION POSSIBLE. THIS WILL
SUPPORT THE IDEA THAT IF STRATUS IS ALLOWED TO DEVELOP TONIGHT, IT
WILL ONLY BE ABLE TO MAKE IT TO COASTAL AND BAYSHORE TERMINALS AT
MOST - PROBABILITIES ARE AT 80% FOR THE COASTAL TERMINALS OF HAF AND
MRY AND BETWEEN 40-60% FOR BAYSHORE TERMINALS OF APC, OAK, AND SFO
(AS WELL AS SNS).
VICINITY OF SFO...CURRENTLY VFR WITH WESTERLY FLOW. MODERATE (40-
60%) CONFIDENCE ON A SUB-VFR CEILING RETURNING TO THE TERMINAL
TONIGHT, LIKELY IFR. WESTERLY WINDS WILL PREVAIL THROUGH THE TAF
PERIOD.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...CURRENTLY VFR WITH WESTERLY FLOW AT MRY AND
VFR WITH NORTHERLY FLOW AT SNS. MODERATE TO HIGH (60-80%) CONFIDENCE
IN SUB-VFR CEILINGS RETURNING TO BOTH TERMINALS TONIGHT, LIKELY ON
THE CUSP OF LIFR/IFR.
MARINE
(TODAY THROUGH SUNDAY)
ISSUED AT 407 AM PDT TUE AUG 19 2025
WIDESPREAD HAZARDOUS CONDITIONS FOR SMALL CRAFT WILL BE PRESENT
TODAY. NORTHWESTERLY BREEZES WILL FLUCTUATE BETWEEN MODERATE AND
STRONG, PARTICULARLY FOR THE OUTER WATERS AND COASTAL JET REGIONS
OF POINT REYES AND POINT SUR. MODERATE SEAS WILL PREVAIL TODAY,
BUILDING TO BECOME ROUGH FOR THE OUTER WATERS BY WEDNESDAY.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 9 PM PDT THIS
EVENING FOR MRY BAY-PT REYES TO PIGEON PT 0-10 NM-SF BAY N
OF BAY BRIDGE.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 3 AM PDT
WEDNESDAY FOR PT ARENA TO PT REYES 0-10 NM.
SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 9 PM PDT THIS
EVENING FOR PIGEON PT TO PT PINOS 0-10 NM.
SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 9 AM PDT
WEDNESDAY FOR PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 9 AM PDT
WEDNESDAY FOR PIGEON PT TO PT PINOS 10-60 NM-PT ARENA TO PT
REYES 10-60 NM.
SHORT TERM...CANEPA
LONG TERM....CANEPA
AVIATION...SARMENT
MARINE...SARMENT
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