129
FXUS65 KSLC 202248
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
348 PM MST WED NOV 20 2024
SYNOPSIS
HIGH PRESSURE WILL BRING A WARMING AND DRYING TREND TO
THE REGION THROUGH THE END OF THE WORKWEEK. A MOISTURE-PACKED
PACIFIC STORM SYSTEM WILL IMPACT THE REGION OVER THE WEEKEND AND
INTO EARLY NEXT WEEK.
SHORT TERM (THROUGH 12Z/5AM FRIDAY)
A SHALLOW RIDGE IN PLACE
WILL ALLOW FURTHER WARM-AIR ADVECTION ACROSS MUCH OF THE FORECAST
AREA TODAY AND THURSDAY, WITH THURSDAY AFTERNOON HIGHS REACHING
INTO THE 50S ACROSS MANY UTAH VALLEYS (5-10 DEGREES ABOVE NORMAL).
SCATTERED HIGH CLOUDS WILL PERSIST, PARTICULARLY FURTHER NORTH
AND WEST, WITH EVEN SOME LOW PRECIPITATION CHANCES IN THE RAFT
RIVER RANGE IN EXTREME NORTHWEST UTAH GIVEN ITS LOCATION ALONG THE
PERIPHERY OF PACIFIC MOISTURE TO OUR NORTHWEST.
LONG TERM (AFTER 12Z/5AM FRIDAY)
WARM SOUTHERLY FLOW ALOFT WILL
BE IN PLACE ON FRIDAY AS HIGH PRESSURE WILL BE SHIFTING TO OUR EAST.
THIS WILL ALLOW TEMPERATURES TO RUN 5-10 DEGREES ABOVE NORMAL. THIS
PATTERN WILL CONTINUE THROUGH MOST OF THE DAY ON SATURDAY BEFORE A
PNW TROUGH EJECTS A SHORTWAVE INTO THE NORTHERN PORTIONS OF THE CWA.
SUBTLE DIFFERENCES IN THE TRAJECTORY OF THIS SHORTWAVE TROUGH COULD
PRODUCE VAST DIFFERENCES IN PRECIPITATION ACROSS THE REGION. BRIEF
RIDGING ON MONDAY WILL BRING A LULL TO THE ACTIVITY BEFORE THE AXIS
OF THE TROUGH TRIES TO PUSH INLAND AND BRING ANOTHER PERIOD OF
ACTIVE WEATHER FOR THE END OF THE LONG TERM.
A PNW ATMOSPHERIC RIVER IS CURRENTLY ONGOING ACROSS THE PNW FROM
NORTHERN CALIFORNIA UP THROUGH BRITISH COLUMBIA THANKS TO AN
IMPRESSIVE CYCLONE OFF THE PNW COAST. THIS CYCLONIC CIRCULATION WILL
STAY MOSTLY STATIONARY OFF THE COAST OF SOUTHERN BRITISH COLUMBIA
THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK. THIS CYCLONE WILL
EJECT A SHORTWAVE TO THE EAST THIS WEEKEND WITH FLOW ALOFT
TRANSITIONING TO WESTERLY ALLOWING MOISTURE TO ADVECT INTO THE
REGION. A STOUT 130+ KNOT JET WILL ACCOMPANY THE WAVE AND PROVIDE
MODEST SYNOPTIC SCALE ACCENT WITHIN THE LEFT EXIT REGION OF THE JET
TO GENERATE WIDESPREAD PRECIPITATION. THE QUESTION IS WHERE THIS
EXIT REGION SETS UP. ~42% OF ENSEMBLE MEMBERS ORIENTS THE JET IN
SUCH A WAY THAT WOULD FAVOR MORE WIDESPREAD PRECIPITATION ACROSS
UTAH (WITH A FOCUS ACROSS NORTHERN UTAH) AND SW WYOMING, BUT THE
REMAINING MEMBERSHIP DEPICTS A DRIER SCENARIO. THIS IS EVIDENT IN
THE WIDE RANGE IN QPF TOTALS IN THE 25TH-75TH PERCENTILES. 75TH
PERCENTILE PRECIPITATION IS ~0.5-0.6" ACROSS MOST VALLEYS OF CENTRAL
AND SOUTHERN UTAH, WITH LESSER AMOUNTS FURTHER SOUTH, AND ~1"+ FOR
MOUNTAIN AREAS. THESE TOTALS ARE CUT IN HALF, OR MORE, FOR THE 25TH
PERCENTILE.
H7 TEMPERATURE ENSEMBLE MEANS BOTTOM OUT ~-8C ACROSS NORTHERN
UTAH/SW WYOMING ON SUNDAY MORNING SUGGESTING SNOW LEVELS LIKELY
REMAIN ABOVE VALLEYS FLOORS. THIS WOULD TRANSLATE TO SURFACE
TEMPERATURES RETURNING BACK TO NEAR NORMAL, OR A FEW DEGREES BELOW
NORMAL. MOST OF THE GUIDANCE IS IN FAVOR OF A RETURN TO SOUTHERLY
FLOW AND SHORTWAVE RIDGING ON MONDAY THAT WOULD BRING A LULL IN
ACTIVITY. THERE IS A 60% CHANCE OF THE AFOREMENTIONED CYCLONE MOVING
ONSHORE AND THROUGH THE REGION BY LATE TUESDAY INTO WEDNESDAY WITH
THE OTHER 40% KEEPING IT OFFSHORE WITH CONTINUED RIDGING. THE MORE
LIKELY SCENARIO WOULD FAVOR COLDER CONDITIONS THAT COULD BRING
ACCUMULATING SNOW TO VALLEY LOCATIONS.
AVIATION...KSLC
NORTHWEST WINDS ARE EXPECTED TO TRANSITION
BACK TO SOUTHEASTERLY AROUND 02-03Z, WITH INCREASING SOUTHERLY
WINDS ONCE AGAIN AROUND 17-18Z THURSDAY. VFR CONDITIONS WILL
PREVAIL WITH SCT-BKN MID TO HIGH CLOUDS.
REST OF UTAH AND SOUTHWEST WYOMING...GUSTY SOUTHERLY WINDS WILL
LARGELY BECOME LIGHTER AND TERRAIN-DRIVEN AFTER 01-02Z, THOUGH
SOME SPOTS MAY CONTINUE TO SEE SOUTHERLY WINDS AROUND 10-15KTS
OVERNIGHT (SUCH AS KU42/KSVR). VFR CONDITIONS WILL PREVAIL WITH
SCT-BKN MID TO HIGH CLOUDS.
SLC WATCHES/WARNINGS/ADVISORIES
UT...NONE.
WY...NONE.
CUNNINGHAM/MAHAN
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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