Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 262348
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
448 PM MST THU FEB 26 2015

.SYNOPSIS...A WEATHER DISTURBANCE WILL CONTINUE TO TRACK SOUTHEAST
ACROSS UTAH THROUGH THIS EVENING. A DEVELOPING STORM SYSTEM WILL
AFFECT MUCH OF THE SOUTHERN AND CENTRAL GREAT BASIN THIS WEEKEND. A
THIRD STORM WILL IMPACT THE ENTIRE AREA THE FIRST HALF OF NEXT WEEK.

&&

.SHORT TERM (THROUGH 00Z MONDAY)...A MOIST AND SOMEWHAT UNSTABLE
CYCLONIC NORTHWEST FLOW IS IN PLACE OVER UTAH THIS AFTERNOON AS A
WEAK SHORTWAVE TROUGH CONTINUES TO CROSS THE AREA. SCATTERED
SHOWERS...SNOW IN THE MOUNTAINS AND HIGHER VALLEYS/BENCHES AND
RAIN/SNOW IN THE LOWER VALLEYS...WILL CONTINUE THROUGH THIS
EVENING...THEN BECOME MORE ISOLATED AND MOSTLY CONFINED TO THE NORTH
AFTER SUNSET. A SLIGHTLY COOLER NIGHT THAN LAST NIGHT IS EXPECTED
ACROSS MANY AREAS DUE TO THE COLD AIR ADVECTION TODAY AND SOME
BREAKS IN THE CLOUDS TONIGHT. OTHERWISE...A NORTHEASTERLY PRESSURE
GRADIENT EXISTS OVER SOUTHWEST WYOMING AND IS ASSOCIATED WITH A
BOUNDARY PUSHING IN FROM THE NORTHEAST. HOWEVER...THIS PUSH IS
RELATIVELY SHALLOW AND THE BULK OF THE COLD AIR WILL REMAIN IN
WYOMING.

WEAK SHORTWAVE RIDGING WILL DEVELOP TOMORROW AFTERNOON AS THE AREA
WILL BE BETWEEN SYSTEMS. HOWEVER...STRENGTHENING H7 WARM AIR
ADVECTION TOMORROW WILL DRIVE SOME ADDITIONAL PRECIPITATION
TOMORROW.

THE NEXT STORM SYSTEM WILL DROP IN FROM THE PACIFIC NORTHWEST ON
FRIDAY AND CARVE SOUTH ALONG THE WEST COAST. THIS WILL THEN DEVELOP
INTO AN ELONGATED TROUGH WITH AXIS EXTENDING NORTHEAST TO SOUTHWEST
BY SATURDAY. PRECIPITATION WILL INCREASE ACROSS SOUTHERN UTAH FRIDAY
NIGHT AHEAD OF THIS SYSTEM AND CONTINUE AT TIMES THROUGH THE
WEEKEND...SPREADING INTO AT LEAST CENTRAL UTAH. SOME UNCERTAINTY
REGARDING THE NORTHERN EXTENT OF HEAVY PRECIPITATION STILL EXISTS AS
IT DEPENDS ON THE LOCATION OF THE DEFORMATION AXIS DRIVING SOME OF
THE HEAVIER PRECIP...BUT BULK OF THIS IS EXPECTED TO OCCUR ACROSS
MOST OF THE SOUTH AS WELL AS SOME EASTERN VALLEYS. SNOW LEVELS
ACROSS SOUTHEAST UTAH MAY BE A BIT HIGHER THAN LAST WEEKENDS
SOUTHERN UTAH STORM...DUE TO A MILD SOUTHWEST FLOW...AT LEAST
THROUGH SATURDAY. AS A RESULT...ACCUMULATIONS IN MOST SOUTHERN UTAH
VALLEYS RIGHT NOW...WHILE STILL RELATIVELY SIGNIFICANT...ARE FORECAST
IN THE ADVISORY RANGE SO DO NOT HAVE ANY WINTER WEATHER HIGHLIGHTS
OUT AT THIS TIME. HOWEVER...HIGHER ELEVATION AREAS...ESPECIALLY
ABOVE 5500-6000FT COULD SEE SIGNIFICANT TOTALS AND A WINTER STORM
WATCH HAS BEEN ISSUED FOR THE SOUTHERN AND CENTRAL MOUNTAINS AND
INCLUDES HIGHER THE PASSES ALONG I-15/I-70 ACROSS SOUTHERN UTAH.

GIVEN THE ORIENTATION OF THE TROUGH...ANOTHER CONCERN WILL BE
EASTERLY CANYON WINDS ACROSS NORTHERN UTAH. THIS COULD OCCUR AS
EARLY AS FRIDAY NIGHT WITH A STRENGTHENING SURFACE GRADIENT...BUT
WITH NO SUPPORT AT 700MB THIS WILL BE SHALLOW WITH SOME ENHANCED
WINDS CONFINED LOCALLY TO THE CANYONS. HOWEVER...H7 WINDS AND
ASSOCIATED COLD ADVECTION LOOKS TO STRENGTHEN ACROSS THE TERRAIN
SATURDAY NIGHT SO STRONGER AND MORE WIDESPREAD EASTERLIES WILL BE
POSSIBLE DURING THIS TIMEFRAME.

&&

.LONG TERM (AFTER 00Z MONDAY)...AN ELONGATED TROUGH AXIS IS EXPECTED
TO BE LOCATED FROM THE WESTERN GREAT BASIN TO OFFSHORE SOUTHERN
CALIFORNIA AT THE BEGINNING OF THE LONG TERM FORECAST PERIOD.
ANOTHER SHORTWAVE IS EXPECTED TO BE PROGRESSING AROUND THE EAST SIDE
OF THE EASTERN PACIFIC HIGH DOWN THE PACIFIC COAST. THIS UPSTREAM
SHORTWAVE IS EXPECTED TO DISLODGE THE FIRST TROUGH WHICH WILL CROSS
ARIZONA INTO NEW MEXICO THROUGH LATE MONDAY. PRECIPITATION IS LIKELY
TO BE ONGOING AT THE START OF THE LONG TERM FORECAST ACROSS PORTIONS
OF SOUTHERN UTAH...WITH MORE SPOTTY PRECIPITATION ASSOCIATED WITH
THE DEFORMATION AXIS ACROSS PORTIONS OF CENTRAL AND SOUTHERN UTAH.

THE UPSTREAM SHORTWAVE IS EXPECTED TO QUICKLY PROGRESS ACROSS THE
DESERT SOUTHWEST TUESDAY. NEXT UP IN THE TRAIN OF SYSTEMS IMPACTING
UTAH...ANOTHER SHORTWAVE DIVING SOUTH FROM INTERIOR CANADA IS
EXPECTED TO BRING A SIGNIFICANT COLD FRONT THROUGH THE AREA TUESDAY.
BOTH THE 12Z GFS AND EC DEPICT 700MB TEMPERATURES FALLING TO BELOW
-20C BY TUESDAY NIGHT BEHIND THIS COLD FRONT ACROSS NORTHERN AND
CENTRAL UTAH. WHILE THE GLOBAL MODELS HAVE BEEN TRENDING FURTHER
EAST WITH THIS SYSTEM...FEEL THERE IS ENOUGH CONFIDENCE IN A COLDER
AIRMASS ACROSS THE STATE TO DECREASE TEMPERATURES SIGNIFICANTLY
BELOW NORMAL FROM ROUGHLY WEDNESDAY ONWARD. MOST OF THE MODEL
GUIDANCE INDICATES THERE IS A THREAT OF PRECIPITATION NEAR AND
BEHIND THE COLD FRONT TUESDAY INTO WEDNESDAY. STARTED UPPING THE
POPS DURING THIS PERIOD ABOVE CLIMO. ANY PRECIPITATION WOULD LIKELY
BE SNOW GIVEN THE CURRENT MODEL CONSENSUS.


&&

.AVIATION...RAIN/SNOW SHOWERS WILL CONTINUE TO IMPACT THE SLC
TERMINAL THROUGH THE AFTERNOON AND INTO THE EVENING. EXPECT
OCCASIONAL CEILINGS NEAR 2000-3000 FEET AGL NEAR ANY SHOWERS THROUGH
AT LEAST 03Z. NORTH TO NORTHWESTERLY WINDS WILL CONTINUE THROUGH 03-
04Z.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WATCH FROM FRIDAY EVENING THROUGH SUNDAY EVENING
     FOR UTZ517-518.
WY...NONE.
&&

$$

CHENG/KRUSE

FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)

FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)


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