884
FXUS65 KSLC 202056
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
256 PM MDT MON OCT 20 2025
SYNOPSIS
HIGH PRESSURE WILL SHIFT ACROSS THE REGION THROUGH
TUESDAY. AN UPPER LEVEL SYSTEM CROSSING THE DESERT SOUTHWEST WILL
IMPACT SOUTHERN UTAH WEDNESDAY INTO THURSDAY. A COLD PACIFIC
SYSTEM WILL BRING THE THREAT OF IMPACTFUL MOUNTAIN SNOW TO THE
NORTHERN MOUNTAINS SUNDAY INTO MONDAY.
DISCUSSION
EARLY AFTERNOON UPPER AIR AND SATELLITE ANALYSIS
INDICATES BROAD UPPER LEVEL RIDGING ACROSS THE SOUTHERN TIER OF
THE UNITED STATES. AN UPPER LEVEL LOW REMAINS OFF THE COAST OF
SOUTHERN CALIFORNIA WHILE AN ACTIVE NORTHERN JET STREAM CONTINUES
TO SHOW A TROUGH TRAIN ACROSS THE EASTERN PACIFIC.
FOR THE NEXT FEW DAYS, HIGH PRESSURE WILL SHIFT ACROSS THE
SOUTHWEST. THE COLDEST MORNING OF THE FALL IS EXPECTED ACROSS MUCH
OF NORTHERN UTAH, WITH FREEZING CONDITIONS EXPECTED FOR EASTERN
BOX ELDER COUNTY AND WEBER COUNTY WEST OF I-15. A FREEZE WARNING
HAS BEEN ISSUED FOR THESE LOCATIONS THIS EVENING THROUGH TUESDAY
MORNING.
THE PREVIOUSLY MENTIONED UPPER LEVEL LOW WILL GRADUALLY SHIFT
ACROSS THE DESERT SOUTHWEST WEDNESDAY INTO THURSDAY. THIS SYSTEM
WILL HAVE A SOMEWHAT TROPICAL MOISTURE TAP, WITH PWS REACHING
AROUND 90TH PERCENTILE FOR THIS TIME OF YEAR. THE EFI (EXTREME
FORECAST INDEX) HIGHLIGHTS SOUTHWESTERN UTAH DURING THIS PERIOD
FOR ANOMALOUS VALUES OF CAPE, WITH A SHIFT OF TALES INDICATING
SOME MEMBERS ARE SHOWING EVEN MORE ANOMALOUS CAPE VALUES. THIS MAY
TRANSLATE INTO A TRANSIENT FLASH FLOOD THREAT WEDNESDAY AFTERNOON
INTO THURSDAY EVENING.
AFTER THIS UPPER LEVEL LOW EJECTS INTO THE PLAINS BY FRIDAY
MORNING, A RELATIVE LULL IN THE WEATHER IS EXPECTED AS SHORTWAVE
RIDGING CROSSES THE REGION. BY SUNDAY, A TROUGH ASSOCIATED WITH A
DECAYING ATMOSPHERIC RIVER WILL PUSH A COLD FRONT INTO NORTHERN
UTAH. ROUGHLY 60% OF THE ENSEMBLE MEMBERS SUPPORT A PROLONGED
PERIOD OF PRECIPITATION ASSOCIATED WITH AND BEHIND THIS FRONT
ACROSS NORTHERN UTAH ASSOCIATED WITH PREFERENTIAL JET DYNAMICS
INTO MONDAY. THE 25TH TO 75TH PERCENTILE SNOW ACCUMULATIONS ARE
AROUND 4 TO 14 INCHES FOR MOST OF THE NORTHERN MOUNTAINS, WITH 8
TO 18 INCHES FOR THE COTTONWOODS. SNOW LEVELS MAY APPROACH VALLEY
FLOORS, BUT IT'S A BIT TOO EARLY TO GET EXCITED FOR THIS (SORRY
SNOW LOVERS).
THAT SAID, THOSE WITH PLANS TO RECREATE OR HUNT IN THE MOUNTAINS
THIS WEEKEND SHOULD BE PREPARED FOR WINTER CONDITIONS INCLUDING
SIGNIFICANT MOUNTAIN SNOW.
AVIATION...KSLC
LIGHT NORTHWEST WINDS WILL LAST THROUGH 03Z WHEN
WINDS TRANSITION TO LIGHT SOUTHEAST. CLEAR CONDITIONS WILL CONTINUE,
WITH A TRANSITION TO LIGHT NORTHWEST WINDS AROUND 18Z.
REST OF UTAH AND SOUTHWEST WYOMING
WEST TO NORTHWEST WINDS
GUSTING AROUND 20 KNOTS WILL DIMINISH THROUGH THE EVENING, WITH
LIGHT WINDS AND CLEAR CONDITIONS PREVAILING FOR THE REMAINDER OF THE
TAF PERIOD.
SLC WATCHES/WARNINGS/ADVISORIES
UT...FREEZE WARNING FROM 8 PM THIS EVENING TO 9 AM MDT TUESDAY FOR
UTZ103-104.
WY...NONE.
KRUSE/WHITLAM
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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