527
FXUS66 KSGX 190515
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
915 PM PST SUN JAN 18 2026
SYNOPSIS
WARM WEATHER WILL CONTINUE THROUGH TUESDAY WITH HIGHS AROUND 5 TO
15 DEGREES ABOVE NORMAL. THE MARINE LAYER WILL BEGIN TO SLOWLY
REBUILD WITH THE POTENTIAL FOR PATCHY DENSE FOG ALONG THE COAST
EACH NIGHT AND MORNING THROUGH TUESDAY, FOLLOWED BY MORE
WIDESPREAD LOW CLOUD COVERAGE BEGINNING TUESDAY NIGHT. OFFSHORE
FLOW BRIEFLY RETURNS MONDAY NIGHT INTO TUESDAY MORNING WITH BREEZY
CONDITIONS BELOW THE PASSES. A COOLING TREND BEGINS ON WEDNESDAY
INTO LATE WEEK AS A LOW PRESSURE SYSTEM MOVES CLOSER TO THE
REGION, HELPING BUILD THE MARINE LAYER EVEN FURTHER. THERE IS A
10-15% CHANCE OF PRECIPITATION LATE IN THE WEEK.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
EVENING UPDATE...
SCATTERED HIGH CLOUDS CONTINUE TO MOVE OVER THE REGION THIS
EVENING. WINDS AT NORTH ISLAND (CORONADO) BRIEFLY TURNED
SOUTHERLY, USHERING HIGHER DEW POINT MARINE AIR, BUT SO FAR NO FOG
HAS DEVELOPED. ELSEWHERE ALONG THE COAST DEW POINTS REMAIN IN THE
UPPER 30S TO LOW 40S. THE HREF IS SHOWING AROUND A 35-45% CHANCE
OF FOG DEVELOPING OVER THE COASTAL WATERS TONIGHT, BUT AS LONG AS
THERE IS ENOUGH DRAINAGE FLOW OVERNIGHT THE DRIER AIRMASS SHOULD
BE ABLE TO HOLD AT THE COAST, LIMITING THE FOG POTENTIAL OVER LAND
AREAS.
A WEAK UPPER LEVEL SHORT WAVE WILL DIG THROUGH THE GREAT BASIN ON
MONDAY, HELPING BREAK DOWN THE NEARBY RIDGE. WITH THE RETURN OF AT
LEAST A WEAK SEA BREEZE, EXPECT A COUPLE DEGREES OF COOLING WEST
OF THE MOUNTAINS WITH LITTLE CHANGE FURTHER INLAND. MARINE LAYER
LOW CLOUDS AND FOG WILL HAVE A BETTER CHANCE (40-50%) OF
DEVELOPING ALONG THE COAST MONDAY EVENING. ONCE THE SHORT WAVE
PASSES, ANOTHER ROUND OF OFFSHORE FLOW DEVELOPS MONDAY NIGHT INTO
TUESDAY MORNING AS SURFACE HIGH PRESSURE STRENGTHENS OVER THE
GREAT BASIN, HELPING CLEAR OUT ANY LOW CLOUDS OVERNIGHT. THIS IS
CURRENTLY FORECAST TO BE A WEAK EVENT, WITH GUSTS AROUND 30-40 MPH
BELOW THE PASSES AND CANYONS PRONE TO NORTH/NORTHEAST WINDS. THE
UPPER LEVEL RIDGE WILL ALSO REBUILD, LEADING TO ANOTHER BRIEF
WARM-UP ON TUESDAY WITH HIGHS IN THE VALLEYS REACHING THE LOW 80S.
PREVIOUS DISCUSSION...
MODELS SHOW AN AREA OF LOW PRESSURE MOVING CLOSER TO THE REGION ON
WEDNESDAY INTO LATER IN THE WEEK. THIS WILL ENHANCE ONSHORE FLOW
AND BUILD THE MARINE LAYER WITH GREATER CLOUD COVERAGE INTO THE
WESTERN VALLEYS EACH NIGHT AND MORNING. HIGH TEMPERATURES WILL
LOWER A FEW DEGREES EACH DAY STARTING WEDNESDAY INTO FRIDAY AS THE
LOW PRESSURE SYSTEM MOVES CLOSER. THERE IS STILL GREAT UNCERTAINTY
ON THE PATH OF THIS LOW PRESSURE SYSTEM. MODEL ENSEMBLES HAVE
DECREASED IN TOTAL RAIN ACCUMULATIONS SINCE YESTERDAY, ALONG WITH
LOWER CHANCES FROM THE NBM, INDICATING LESS THAN A 15% CHANCE OF
ANY MEASURABLE RAINFALL BY FRIDAY INTO NEXT WEEKEND.
BY EARLY NEXT WEEK, MODEL GUIDANCE IS FAIRLY AGREEABLE TO WEAK
HIGH PRESSURE MOVING BACK INTO THE AREA WITH POTENTIALLY MORE
OFFSHORE FLOW. THIS PATTERN WOULD GIVE US WARMER AND DRIER
WEATHER AS WE HEAD INTO THE LAST FULL WEEK OF JANUARY.
AVIATION
190500Z...FEW HIGH CLOUDS AND VFR CONDITIONS PREVAIL FOR INLAND
AREAS THROUGH MONDAY NIGHT. NORTH AND EAST WINDS TO INCREASE AFTER
00Z TUE FOR THE MOUNTAIN PASSES AND COASTAL SLOPES WITH GUSTS UP TO
35 KTS.
AT THE COAST, VERY LOCALIZED FG WITH VIS < 1/2SM TO DEVELOP AFTER
11Z, MORE LIKELY OFF OF COASTAL ORANGE COUNTY. THROUGH 17Z MON,
THERE IS A 25% CHANCE FOR BRIEF FG IMPACTS AT KSNA AND A 10% CHANCE
AT KCRQ AND KSAN. GREATER COVERAGE IN FG IS EXPECTED MONDAY EVENING,
DEVELOPING IN PATCHY FASHION ALONG THE IMMEDIATE COAST SOMETIME
BETWEEN 02-06Z TUE. 30-40% CHANCE FOR FG IMPACTS FOR THE COASTAL TAF
SITES MONDAY EVENING.
MARINE
VERY LOCALIZED DENSE FOG TO DEVELOP TONIGHT INTO EARLY MONDAY AND
MORE LIKELY (35-45% CHANCE) MONDAY NIGHT INTO TUESDAY. PATCHY FOG
CAN RESULT IN VISIBILITY DROPPING LOCALLY BELOW 1 NAUTICAL MILE.
OTHERWISE, NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH
THURSDAY.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
PUBLIC...SS
AVIATION/MARINE...WESTERINK
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