655
FNUS76 KSGX 211848
FWSSGX
SPOT FORECAST FOR GRAND IC...SAN MARCOS EM
NATIONAL WEATHER SERVICE SAN DIEGO CA
1048 AM PST WED JAN 21 2026
FORECAST IS BASED ON FORECAST START TIME OF 1100 PST ON JANUARY 21.
IF CONDITIONS BECOME UNREPRESENTATIVE, CONTACT THE NATIONAL WEATHER
SERVICE.
DISCUSSION
RELATIVELY LIGHT WINDS EXPECTED FOR THE FORECAST AREA TODAY AND
FOR THE NEXT FEW DAYS. WINDS PREDOMINANTLY OUT OF THE WEST-
SOUTHWEST GENERALLY 5-10 MPH DURING THE LATE MORNING AND
AFTERNOON HOURS TODAY, THURSDAY, AND FRIDAY. MIXING HEIGHT REMAINS
FAIRLY SHALLOW THIS AFTERNOON, ONLY MIXING THROUGH A LITTLE HIGHER
THAN 1000FT, BUT THE MARINE LAYER BRINGS IN LOW CLOUDS AND PATCHY
FOG IN TONIGHT AND MORE SURFACE STABILITY, LIMITING THE MIXING TO
300-600FT WHICH COULD TRAP SMOKE CLOSER TO THE SURFACE. MIXING
HEIGHT GRADUALLY INCREASES THURSDAY INTO FRIDAY, WITH LESS SURFACE
TRAPPING EXPECTED BY FRIDAY MORNING. THERE IS A SLIGHT CHANCE FOR
A FEW STRAY SHOWERS BEGINNING LATE THURSDAY MORNING, CONTINUING
INTO FRIDAY. ANY RAIN THAT DOES OCCUR WILL BE FAIRLY INTERMITTENT
AND LIGHT WITH TOTAL ACCUMULATIONS LIKELY UNDER 0.05" THROUGH
FRIDAY AFTERNOON.
REST OF TODAY
SKY/WEATHER.........MOSTLY CLOUDY (75-85 PERCENT).
MAX TEMPERATURE.....AROUND 69.
MIN HUMIDITY........50 PERCENT.
SURFACE WINDS (MPH).LIGHT WINDS.
CHANCE OF PCPN......0 PERCENT.
MIXING HEIGHT.......1100 FT AGL.
MIXING WINDS........SOUTHWEST 2 TO 5 MPH SHIFTING TO THE WEST
AROUND 5 MPH LATE IN THE AFTERNOON.
TIME (PST) 11A 12P 1PM 2PM 3PM 4PM 5PM
SKY (%).........77 77 82 82 82 87 87
WEATHER COV.....
WEATHER TYPE....
TSTM COV........
TEMP............65 66 67 66 65 63 60
RH..............50 51 53 59 61 65 74
SURFACE WND DIR.SW SW SW SW W W W
SURFACE WND SPD.3 3 3 4 4 4 3
SURFACE WND GST.7 8 9 9 10 9 7
MIX HGT (KFT)...0.7 1.0 1.1 1.1 0.8 0.8 0.6
MIXING WIND DIR.S S SW SW SW W W
MIXING WIND SPD.2 3 5 5 5 5 5
CHC OF PCPN (%).0 0 0 0 0 0 0
TONIGHT
SKY/WEATHER.........MOSTLY CLOUDY (75-85 PERCENT). PATCHY FOG IN
THE EVENING.
MIN TEMPERATURE.....AROUND 50.
MAX HUMIDITY........97 PERCENT.
SURFACE WINDS (MPH).LIGHT WINDS.
CHANCE OF PCPN......10 PERCENT.
MIXING HEIGHT.......300 FT AGL.
MIXING WINDS........SOUTHWEST 1 TO 2 MPH SHIFTING TO THE SOUTH
AROUND 1 MPH EARLY IN THE EVENING, THEN
SHIFTING TO THE EAST 1 TO 2 MPH LATE IN THE
EVENING SHIFTING TO THE SOUTHEAST 2 TO 3 MPH
LATE IN THE EVENING SHIFTING TO THE EAST AROUND
3 MPH.
TIME (PST) 6PM 7PM 8PM 9PM 10P 11P MID 1AM 2AM 3AM 4AM 5AM
SKY (%).........87 85 85 85 85 85 85 74 74 74 78 78
WEATHER COV..... PTY PTY PTY PTY PTY PTY
WEATHER TYPE.... FOG FOG FOG FOG FOG FOG
TSTM COV........
TEMP............58 57 56 56 55 54 53 53 52 52 52 51
RH..............83 86 88 89 85 90 91 93 91 93 96 97
SURFACE WND DIR.W NW SE E E SE S S SE E E E
SURFACE WND SPD.3 1 1 1 3 1 1 1 3 3 3 3
SURFACE WND GST.6 5 6 6 6 6 6 7 7
MIX HGT (KFT)...0.4 0.3 0.3 0.3 0.3 0.3 0.3 0.4 0.4 0.5 0.4 0.3
MIXING WIND DIR.W SW S E E S S SE S S SE E
MIXING WIND SPD.2 1 1 1 2 2 2 2 2 2 3 3
CHC OF PCPN (%).0 0 0 0 10 10 10 10 10 10 10 10
THURSDAY
SKY/WEATHER.........MOSTLY CLOUDY (80-90 PERCENT) THEN BECOMING
PARTLY CLOUDY (65-75 PERCENT). SLIGHT CHANCE OF
RAIN SHOWERS IN THE LATE MORNING AND EARLY
AFTERNOON. CHANCE OF RAIN SHOWERS LATE IN THE
AFTERNOON.
MAX TEMPERATURE.....AROUND 66.
MIN HUMIDITY........69 PERCENT.
SURFACE WINDS (MPH).LIGHT WINDS.
CHANCE OF PCPN......30 PERCENT.
MIXING HEIGHT.......1800 FT AGL.
MIXING WINDS........EAST AROUND 2 MPH SHIFTING TO THE WEST 2 TO 6
MPH IN THE LATE MORNING AND AFTERNOON.
TIME (PST) 6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM
SKY (%).........78 89 89 89 86 86 86 79 79 79 69 69
WEATHER COV..... SCH SCH SCH SCH SCH SCH CHC CHC
WEATHER TYPE.... RW RW RW RW RW RW RW RW
TSTM COV........
TEMP............51 51 53 57 61 63 64 64 65 63 62 60
RH..............96 94 96 89 78 72 69 69 70 72 76 81
SURFACE WND DIR.E E E N W W W W W W W W
SURFACE WND SPD.1 1 1 1 3 3 4 4 4 4 3 3
SURFACE WND GST.6 6 7 8 10 10 10 9 8 8
MIX HGT (KFT)...0.2 0.2 0.3 0.6 1.2 1.4 1.6 1.8 1.6 1.3 1.1 0.9
MIXING WIND DIR.E E E W W W W W W W W W
MIXING WIND SPD.2 2 2 2 3 3 3 5 5 6 6 5
CHC OF PCPN (%).10 10 10 10 20 20 20 20 20 20 30 30
THURSDAY NIGHT
SKY/WEATHER.........PARTLY CLOUDY (65-75 PERCENT) THEN BECOMING
CLOUDY (90-100 PERCENT). CHANCE OF RAIN
SHOWERS.
MIN TEMPERATURE.....AROUND 51.
MAX HUMIDITY........100 PERCENT.
SURFACE WINDS (MPH).LIGHT WINDS.
CHANCE OF PCPN......30 PERCENT.
MIXING HEIGHT.......600 FT AGL.
MIXING WINDS........WEST 3 TO 5 MPH SHIFTING TO THE SOUTH AROUND 3
MPH IN THE LATE EVENING AND OVERNIGHT.
TIME (PST) 6PM 7PM 8PM 9PM 10P 11P MID 1AM 2AM 3AM 4AM 5AM
SKY (%).........69 69 69 69 99 99 99 99 99 99 93 93
WEATHER COV.....CHC CHC CHC CHC CHC CHC CHC CHC CHC CHC CHC CHC
WEATHER TYPE....RW RW RW RW RW RW RW RW RW RW RW RW
TSTM COV........
TEMP............57 56 55 53 53 52 52 53 52 52 53 51
RH..............87 92 95 96 96 98 99 100 100 100 100 100
SURFACE WND DIR.W W W NW N SE SE SE E E E E
SURFACE WND SPD.3 3 3 1 0 1 1 3 3 3 3 3
SURFACE WND GST.7 8 7 6 7 7 6 7 7
MIX HGT (KFT)...0.8 0.6 0.7 0.7 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8
MIXING WIND DIR.W W W SW S S S S S S SE SE
MIXING WIND SPD.5 3 3 3 3 3 3 3 3 3 3 3
CHC OF PCPN (%).30 30 30 30 30 30 30 30 30 30 30 30
FRIDAY
SKY/WEATHER.........MOSTLY CLOUDY (75-85 PERCENT). CHANCE OF RAIN
SHOWERS IN THE MORNING AND EARLY AFTERNOON,
THEN SLIGHT CHANCE OF RAIN SHOWERS LATE IN THE
AFTERNOON.
MAX TEMPERATURE.....AROUND 63.
MIN HUMIDITY........76 PERCENT.
SURFACE WINDS (MPH).LIGHT WINDS BECOMING WEST AROUND 7 MPH IN THE
AFTERNOON.
CHANCE OF PCPN......30 PERCENT.
MIXING HEIGHT.......3100 FT AGL.
MIXING WINDS........SOUTHEAST AROUND 3 MPH SHIFTING TO THE WEST
AROUND 6 MPH IN THE AFTERNOON.
TIME (PST) 6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM
SKY (%).........93 93 93 93 92 92 92 92 92 92 70 70
WEATHER COV.....CHC CHC CHC CHC CHC CHC CHC CHC CHC CHC SCH SCH
WEATHER TYPE....RW RW RW RW RW RW RW RW RW RW RW RW
TSTM COV........
TEMP............51 52 55 56 60 58 60 63 60 60 60 56
RH..............100 100 97 90 85 81 78 77 76 76 78 82
SURFACE WND DIR.E E SE SE S SW W W W W W W
SURFACE WND SPD.3 3 3 3 3 3 4 6 7 7 7 6
SURFACE WND GST.7 7 7 7 6 7 9 12 13 14 13 12
MIX HGT (KFT)...0.8 0.8 1.0 1.3 1.5 2.0 2.6 3.1 2.8 2.5 2.2 1.6
MIXING WIND DIR.SE E SE S S S SW W W W W W
MIXING WIND SPD.3 3 3 3 3 5 5 6 6 6 6 6
CHC OF PCPN (%).30 30 30 30 30 30 30 30 30 30 20 20
FORECASTER...DAVID MUNYAN
REQUESTED BY...DAN BARRON
TYPE OF REQUEST...HAZMAT
.TAG 2600798.0/SGX
.DELDT 01/21/26
.FORMATTERVERSION 2.0.0
.EMAIL JSMITH@SANMARCOSCA.GOV,JSMITH@SAN-MARCOS.NET
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