Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 241534
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
834 AM MST TUE FEB 24 2015

.SYNOPSIS...AN UPPER LOW WILL EXIT UTAH THROUGH THIS MORNING.
HIGH PRESSURE WILL BRIEFLY RETURN TO THE AREA THIS
AFTERNOON...FOLLOWED BY A COUPLE OF WEAK WEATHER DISTURBANCES
CROSSING THE REGION TONIGHT THROUGH FRIDAY.

&&

.DISCUSSION...WATER VAPOR LOOP SHOWS A CLOSED LOW OVER NORTHERN
ARIZONA. AMDAR 400-250MB WIND OBSERVATIONS INDICATE A WESTERLY
125-160KT JET ACROSS FAR SOUTHERN CALIFORNIA INTO THE FOUR
CORNERS. GOES/GPS/RAP/12Z RAOB INDICATE THE PRECIPITABLE WATER
VALUE RANGES BETWEEN 0.05-0.10" CENTRAL UTAH...TO 0.30-0.40" FAR
SOUTH. BLENDED TOTAL PRECIPITABLE WATER PRODUCT INDICATES
ABNORMALLY DRY AIRMASS OVER THE GREAT BASIN AND ABNORMALLY MOIST
AIRMASS ACROSS THE FAR NORTHERN ROCKIES.

SHOULD BE A QUIET DAY AS THE RIDGE BUILDS IN BEHIND THE CLOSED LOW.
CONTINUED TO UNDERCUT BIAS CORRECTED GUIDANCE FOR TEMPERATURES
GIVEN THE REGIME CHANGE...AND UNDERCUT EVEN FURTHER ACROSS
SOUTHERN UTAH WHERE SNOW FELL. LOWERED POPS ACROSS THE SOUTHEAST
BASED ON RADAR AND MODEL DATA...WITH NO MENTION FOR THE AFTERNOON.

NORTHEAST WINDS WILL REMAIN SOMEWHAT GUSTY ACROSS PORTIONS OF
SOUTHERN UTAH MIXING DOWN STRONGER WINDS ALOFT BEHIND THE STORM
SYSTEM.

&&

PREVIOUS DISCUSSION FOLLOWS...
A CLOSED LOW CONTINUES TO SPIN OVER SOUTHERN UTAH THIS
MORNING...PRODUCING MOSTLY CLOUDY SKIES AND A FEW LINGERING
SHOWERS IN THE SOUTHERN THIRD OF THE CWA. THE SHOWERS THAT ARE
STILL ONGOING HAVE NOT BEEN PARTICULARLY PRODUCTIVE IN THE EARLY
MORNING HOURS...SO HAVE ALLOWED THE WINTER STORM WARNINGS TO
EXPIRE AS PLANNED AT 4 AM MST.

THIS LOW WILL CONTINUE TO EXIT THE AREA TO THE SOUTHEAST THROUGH
THE DAY...WITH SUNNY SKIES EXPECTED ACROSS PRETTY MUCH ALL OF UTAH
AND SOUTHWEST WYOMING AT SOME POINT THIS AFTERNOON. WHILE
TEMPERATURES IN GENERAL SHOULD BE WARMER THAN YESTERDAY...SOME
PLACES WILL STRUGGLE TO WARM SIGNIFICANTLY...INCLUDING VALLEY
LOCATIONS WHERE MIXING WILL BE RELATIVELY HARD TO COME BY...AND
ANYWHERE IN SOUTHERN UTAH WITH AMPLE SNOW COVER.

WEAK SHORTWAVE RIDGING THIS AFTERNOON WILL GIVE WAY TO A MORE
ACTIVE WEST-NORTHWESTERLY FLOW TONIGHT...WHICH WILL REMAIN IN
PLACE THROUGH THURSDAY. A SERIES OF WEAK SHORTWAVES ARE EXPECTED
TO MOVE THROUGH THE REGION IN THIS NORTHWEST FLOW WITH VARYING
STRENGTH AND MOISTURE CONTENT. THE FIRST OF THESE RIPPLES ENTERS
THE AREA TONIGHT...AND COULD BRING SHOWERS TO THE NORTHEASTERN
FRINGES OF THE FORECAST AREA WEDNESDAY AND WEDNESDAY NIGHT.
INCREASED POPS A BIT FOR UINTA COUNTY WYOMING AND THE UINTA
MOUNTAINS THROUGH THIS PERIOD. WHILE PRECIP VALUES SHOULD NOT BE
SIGNIFICANT...MODELS HAVE BEEN PRODUCING AT LEAST SOME QPF IN
THESE AREAS FOR MOST RUNS IN THE PAST FEW DAYS.

A SOMEWHAT DEEPER AND MOISTER SHORTWAVE IS PROGGED TO ENTER THE
AREA ON THURSDAY...WITH SCATTERED SHOWERS POSSIBLE ACROSS A WIDER
PORTION OF NORTHERN AND PERHAPS CENTRAL UTAH. THAT SAID...PRECIP
CURRENTLY LOOKS SPOTTY IN THE VALLEY LOCATIONS...SO HAVE KEPT THE
ONGOING 30-40 POPS FOR NOW. THERE IS A LITTLE MORE CONFIDENCE THAT
THE MOUNTAINS WILL LIKELY GET AT LEAST SOME LIGHT SNOWFALL
THURSDAY AND THURSDAY NIGHT.

WEATHER FOR FRIDAY WILL BE DEPENDENT ON THE DEVELOPMENT OF A
LARGER AND DEEPER LOW DEVELOPING OVER THE PACIFIC
NORTHWEST...WHICH LOOKS TO DIVE SOUTH INTO CALIFORNIA AND NEVADA.
THERE IS SOME DISCREPANCY ABOUT HOW QUICKLY THIS LOW PUSHES MORE
WIDESPREAD PRECIPITATION INTO UTAH...BUT GLOBAL MODELS ARE COMING
INTO BETTER AGREEMENT THAT SOUTHERN UTAH WILL LIKELY GET THE BRUNT
OF THIS STORM YET AGAIN. FOR THE DAYTIME FRIDAY...HAVE INCREASED
POPS A BIT ACROSS SOUTHERN UTAH AND DECREASED POPS SLIGHTLY ACROSS
NORTHERN UTAH. A FAIR AMOUNT OF UNCERTAINTY EXISTS ON WHETHER
HEAVIER PRECIP WILL BEGIN IN EARNEST BEFORE 00Z SATURDAY...BUT
EITHER WAY THE BEST OF THE STORM FOR UTAH WILL LIKELY OCCUR
OVER THE WEEKEND.

THE DEVELOPING UPPER LOW OVER THE PACIFIC NORTHWEST LATE FRIDAY
WILL SETTLE SOUTH INTO THE WESTERN GREAT BASIN/CENTRAL CALIFORNIA
FOR LATE FRIDAY NIGHT/SATURDAY. THIS PATTERN IS NOT ALL THAT
DIFFERENT FROM THE ONE THAT BROUGHT THE RECENT HEAVY SNOWS TO
SOUTHERN UTAH. ONCE AGAIN A BAROCLINIC ZONE WILL STALL ACROSS
SOUTHERN UTAH LATE IN THE WEEK. THE DEVELOPING SOUTHWEST FLOW
AHEAD OF THE UPPER LOW WILL CREATE STRONG CONVERGENCE INTO THIS
BOUNDARY WITH STRONG SYNOPTIC-SCALE LIFT FROM THE UPPER LOW AND
UPPER DIVERGENCE IN THE LEFT EXIT REGION OF THE UPPER JET OVER THE
SOUTHERN GREAT BASIN.

BOTH THE ECMWF AND GFS ARE SIMILAR WITH THE POSITION AND INTENSITY
OF THIS STORM EARLY IN THE WEEKEND. HAVE BOOSTED POPS QUITE A BIT
FOR THE SOUTHERN/CENTRAL ZONES WITH THE IDEA THAT SIGNIFICANT SNOWS
WILL AGAIN COVER MUCH OF SOUTHERN UTAH. ONE CONCERN THAT DOES EXIST
WILL BE THAT THE TRACK OF THIS STORM WILL BE FURTHER SOUTH THAN THE
RECENT EVENT. THE LATEST 06Z GFS DOES SHOW THE TRACK A BIT FURTHER
TO THE SOUTH WITH THE HEAVIEST PRECIP NOW CONFINED TO THE FAR
SOUTHERN PORTION OF THE STATE.

THE PATTERN WILL LIKELY REMAIN ACTIVE NEXT WEEK. THE NEXT PACIFIC
SHORTWAVE IS CURRENTLY DEPICTED AS INTENSIFYING FURTHER NORTH WITH
THE NORTHERN PORTION OF UTAH IN LINE FOR A SIGNIFICANT WINTER EVENT.
NOT ESPECIALLY CONFIDENT IN THIS SOLUTION AS THERE IS POTENTIAL FOR
THIS FEATURE TO FOLLOW THE RECENT STORMS AND DIVE SOUTH INTO THE
WESTERN GREAT BASIN AND THEN EAST ACROSS SOUTHERN UTAH/NORTHERN
ARIZONA. WILL MAINTAIN CHANCE CATEGORY POPS ACROSS THE NORTH FOR NOW
DUE TO THE UNCERTAINTY ON THE TRACK OF THIS NEXT SYSTEM.

&&

.AVIATION...VFR CONDITIONS WITH LIGHT NORTH WINDS WILL PREVAIL AT
KSLC THROUGH THE DAY.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...NONE.
WY...NONE.
&&

$$

PUBLIC...ROGOWSKI/SCHOENING/CONGER
AVIATION...SEAMAN

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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