512
FXUS65 KSLC 251025
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
425 AM MDT SUN AUG 25 2019
SYNOPSIS
A COUPLE OF WEATHER DISTURBANCES MOVING THROUGH THE
NORTHERN ROCKIES TODAY WILL NUDGE A DRY FRONT ACROSS NORTHERN AND
CENTRAL UTAH. COOLER TEMPERATURES WILL FOLLOW THE FRONT FOR THE
EARLY PART OF THE WEEK. A PLUME OF MOISTURE WILL MAKE A BRIEF RETURN
MIDWEEK.
SHORT TERM (THROUGH 00Z THURSDAY)
THE LARGE SCALE PATTERN THIS
MORNING CONSISTS OF A BROAD RIDGE CENTERED NEAR 145W WITH A WEST-
NORTHWESTERLY FLOW ALOFT EXTENDING INTO UTAH. A COUPLE OF SHORTWAVE
DISTURBANCES, ONE CURRENTLY OVER THE NORTHERN ROCKIES AND ANOTHER
OVER THE PACIFIC NORTHWEST, ARE EMBEDDED WITHIN A MEAN TROUGH WHICH
IS MOVING ACROSS THE NORTHWESTERN CONUS. PRECIPITABLE WATER VALUES
REMAIN GENERALLY IN THE 0.6-0.75 INCH RANGE ACROSS MOST VALLEYS.
SKIES ARE MOSTLY CLEAR THIS MORNING WITH JUST A FEW PATCHES OF HIGH
CLOUDS DRIFTING THROUGH CENTRAL UTAH.
THE AFOREMENTIONED DISTURBANCES WILL PUSH A DRY COLD FRONT THROUGH
NORTHERN UTAH TODAY, WITH THE FRONT STALLING OUT OVER CENTRAL UTAH
THIS EVENING. WINDS WILL INCREASE ON BOTH SIDES OF THE FRONT, BUT
ESPECIALLY ACROSS PORTIONS OF NORTHERN UTAH AND THE NORTHEASTERN
THROUGH EAST-CENTRAL VALLEYS GIVEN A WESTERLY MSLP GRADIENT AND 20-
35KT 700MB FLOW THIS AFTERNOON. ALTHOUGH AFTERNOON MAX TEMPERATURES
ARE NOT EXPECTED TO CHANGE SIGNIFICANTLY FROM YESTERDAY'S VALUES,
OVERNIGHT MINS TONIGHT AND AFTERNOON MAXES TOMORROW WILL BE
NOTICEABLY COOLER ACROSS NORTHERN UTAH AND SOUTHWEST WYOMING.
THE RIDGE WILL SHIFT EASTWARD THROUGH THE EARLY PART OF THE WEEK AND
RE-CENTER ITSELF OVER ARIZONA BY MIDWEEK. A SOUTHERLY FLOW ALONG THE
CA/AZ BORDER AND THROUGH SOUTHERN NEVADA WILL DRAW EXISTING MOISTURE
FROM OVER AND AROUND THE GULF OF CALIFORNIA AND BRING IT NORTHWARD
AND INTO SOUTHERN UTAH BY WEDNESDAY. THIS MOISTURE IS EXPECTED TO
LEAD TO A RETURN OF CONVECTIVE ACTIVITY AROUND MIDWEEK.
LONG TERM (AFTER 00Z THURSDAY)
BY THURSDAY, THE RIDGE AXIS IS
EXPECTED TO MOVE BACK OVER UTAH, RESULTING IN A LIGHT AND GENERALLY
WESTERLY FLOW ALOFT. THIS SHOULD CUT OFF THE MOISTURE TAP, BUT
MOISTURE LINGERING OVER THE FORECAST AREA WILL RESULT IN SOME
AFTERNOON/EVENING CONVECTION OVER THE HIGHER TERRAIN FOR THE LATTER
PART OF THE UPCOMING WORK WEEK.
A WEAK TROUGH MOVING OVER THE RIDGE IS PROGGED TO FLATTEN IT
THURSDAY NIGHT INTO EARLY FRIDAY. BEHIND THE EXITING WAVE, GLOBAL
MODELS INDICATE THE RIDGE WILL REAMPLIFY, WITH THE AXIS MOVING WEST
OF THE FORECAST AREA. THIS ORIENTATION OF THE RIDGE WOULD DRY OUT
THE AIRMASS OVER THE AREA, RESULTING IN DECREASING CHANCES OF
CONVECTION OVER THE WEEKEND. THE INFLUENCE OF THE RIDGE SHOULD KEEP
TEMPERATURES NEAR TO JUST ABOVE SEASONAL NORMALS THROUGH THE LONG
TERM PERIOD.
AVIATION
THE SLC TERMINAL WILL SEE VFR CONDITIONS THROUGHOUT THE
DAY WITH MOSTLY CLEAR SKIES. SOUTHEAST WINDS ARE EXPECTED TO SHIFT
TO THE NORTHWEST WITH THE PASSAGE OF A DRY COLD FRONT BETWEEN 17Z
AND 19Z.
FIRE WEATHER
A DRY COLD FRONT WILL PUSH THROUGH NORTHERN UTAH
TODAY BEFORE STALLING OVER CENTRAL UTAH AS A TROUGH CROSSES THE
NORTHERN ROCKIES. WINDS WILL INCREASE NEAR THE FRONT WHICH, COMBINED
WITH LOW HUMIDITIES IN PLACE, WILL LEAD TO HAZARDOUS FIRE WEATHER
CONDITIONS TODAY. LOCALIZED AREAS OF GUSTY WINDS WILL CONTINUE
TOMORROW ACROSS PORTIONS OF EASTERN UTAH WHICH WILL CONTINUE TO
PRODUCE ISOLATED HAZARDOUS FIRE WEATHER CONDITIONS. THE COLD FRONT
WILL BRING COOLER TEMPERATURES TO NORTHERN UTAH LATER TODAY THROUGH
MONDAY. HIGH PRESSURE WILL THEN BUILD OVER THE AREA MIDWEEK, BUT
MOISTURE WILL INCREASE FROM THE SOUTH LEADING TO THE RETURN OF
THUNDERSTORM ACTIVITY.
SLC WATCHES/WARNINGS/ADVISORIES
UT...RED FLAG WARNING FROM 11 AM TO 10 PM MDT SUNDAY FOR UTZ478>484-
488-489.
WY...RED FLAG WARNING FROM 10 AM TO 8 PM MDT SUNDAY FOR WYZ277.
CHENG/TRAPHAGAN
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP
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