Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 060956
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
356 AM MDT FRI MAY 6 2016

.SYNOPSIS...THE UPPER LEVEL LOW PRESSURE SYSTEM OFF THE SOUTHERN
CALIFORNIA COAST MOVE SLOWLY EAST INTO THE GREAT BASIN FOR THE
UPCOMING WEEKEND. A SECOND COLDER STORM SYSTEM WILL MOVE SOUTH
FROM WESTERN CANADA AND MOVE THROUGH THE REGION EARLY NEXT WEEK.

&&

.SHORT TERM (THROUGH 06Z MONDAY)...
WATER VAPOR LOOP SHOWS THE RIDGE SHIFTING EAST OF THE ROCKIES
WITH AN EXPANSIVE CLOSED LOW CENTERED JUST WEST OF SOUTHERN
CALIFORNIA. AMDAR 400-250MB WIND OBSERVATIONS PLACE A CYCLONIC
100-130KT JET OVER THE WATERS OFF OF CALIFORNIA AND INTO ARIZONA.
GOES/HRRR/00Z KSLC RAOB INDICATE THE PRECIPITABLE WATER VALUE
RANGES FROM 0.25"-0.35" SOUTHERN MOUNTAINS TO 0.50"-0.75"
NORTHERN AND EASTERN VALLEYS.

CONVECTION ACROSS THE NORTH AND EAST TODAY WILL BE DRIVEN BY
DIFFLUENCE ALOFT AHEAD OF THE CLOSED LOW...WITH THE LEFT EXIT REGION
OF THE UPPER LEVEL JET OVER THE FOUR CORNERS REGION. THIS AREA IS
COINCIDENT WITH THE BEST DEEP LAYER INSTABILITY PER SHORT RANGE
ENSEMBLES. FORECAST SOUNDINGS ARE INDICATIVE OF A DRY MICROBURST
POTENTIAL WITH INVERTED-V SIGNATURE...THOUGH THERE IS A BETTER
CHANCE FOR MEASURABLE PRECIPITATION THAN YESTERDAY.

SHORT RANGE ENSEMBLES INDICATE AT LEAST 30 KNOTS OF EFFECTIVE SHEAR
ACROSS THE NORTH IN THE DEEPER INSTABILITY. THIS COULD HELP TO
SUSTAIN ORGANIZED CONVECTION. GIVEN THE THERMODYNAMIC
ENVIRONMENT....LOCALLY STRONG WIND GUSTS ARE THE PRIMARY THREAT FROM
THIS CONVECTION.

THE COLD CORE ALOFT ARRIVES TODAY ACROSS SOUTHWEST UTAH. CONVECTION
IN THIS AREA WILL BE MORE WIDESPREAD WITH A MUCH GREATER CHANCE FOR
PRECIPITATION THAN FURTHER NORTH AND EAST.

COLD CORE ALOFT OVERHEAD TONIGHT INTO SUNDAY. WHILE SOME CONVECTIVE
DOWNSWING CAN BE EXPECTED WITH LOSS OF DIURNAL WARMING...IT WILL
REMAIN ACTIVE WITH SCATTERED CONVECTION TONIGHT...WITH BEST CHANCES
NEAR THE MIDLEVEL CIRCULATION IN SOUTHWEST UTAH.

SATURATION AND LOWERING CLOUD BASES EXPECTED SATURDAY AS CONVECTION
INCREASES IN COVERAGE ONCE AGAIN...OFFERING BETTER CHANCE FOR
PRECIPITATION MOST AREAS.

A STRONG WAVE PIVOTS FROM COLORADO INTO WYOMING TOMORROW...WHICH
BRINGS THE POTENTIAL OF INTRODUCING ADDITIONAL WRAP AROUND MOISTURE
MOVING INTO NORTHERN UTAH FROM WYOMING SATURDAY NIGHT AND SUNDAY.

.LONG TERM (AFTER 06Z MONDAY)...
MID LEVEL TROUGH AXIS MOVING SOUTHEAST ACROSS NORTHWEST UTAH WILL
MOVE TO ABOUT A SOUTHERN UTAH COUNTY TO DELTA LINE BY 06Z MONDAY
AND DOWN TO NEAR LAKE POWELL BY MIDDAY. RESIDUAL MOISTURE AND
FAVORABLE NORTHWEST FLOW FOR A FEW HOURS BEHIND THIS TROUGH IS THE
REASON I LEFT SOME LOW END POPS IN ACROSS THE WASATCH FRONT
SOUTHWARD DOWN THE I-15 CORRIDOR TO CEDAR CITY AND ADJACENT
MOUNTAINS FOR THE 06-12Z PERIOD...ALTHOUGH THIS MAY BE OVERDONE.
THE EC IS A LITTLE FASTER WITH THIS TROUGH...HOWEVER IT KEEPS SOME
POPS GOING THROUGH 12Z DESPITE ANTICYCLONIC FLOW AT MID AND HIGH
LEVELS. ENOUGH SUBSIDENCE SHOULD BE PRESENT BETWEEN THE 12 AND 18Z
TIME FRAME FOR LITTLE IF ANY SHOWERS. HAVE PULLED BACK POPS TO
JUST A FEW ISOLATED ACROSS HIGHER TERRAIN. AFTER 18Z THERE SHOULD
BE ENOUGH SUNSHINE TO DEVELOP SOME HIGHER TERRAIN CONVECTION.

BY TUESDAY MORNING A COLD 500 MB TROUGH DROPS SOUTHWARD INTO THE
NORTHERN PORTION OF THE INTERMOUNTAIN REGION. THE EC OPERATIONAL IS
ABOUT 4 DEGREES C COLDER AT 500MB THAN THE GFS. HOWEVER HAVE LEANED
TOWARD THE GFS SOLUTION AS THE 12Z EC ENSEMBLE IS MUCH CLOSER TO THE
GFS. THEREFORE HAVE REMOVED POPS ACROSS NORTHERN PORTIONS OF CWA FOR
TUESDAY AND TUESDAY NIGHT AS THIS FEATURE LOOKS TO BE MORE STABLE
WITH THE COLD AIR ALOFT REMAINING NORTH OF THE GSL. FARTHER SOUTH A
POOL OF MOISTURE IS EXPECTED TO LINGER ACROSS SOUTHWEST UTAH AND
SOUTHERN NEVADA THROUGH TUESDAY AND POSSIBLY INTO WEDNESDAY. HAVE
ADDED ISOLATED POPS OVER THE SOUTHERN UTAH MOUNTAINS FOR THESE
PERIODS DAY TIME PERIODS.

A DRY TREND WITH WARMING TEMPERATURES ARE EXPECTED WEDNESDAY THROUGH
THURSDAY AS THE 500MB TROUGH MOVES EAST OF THE ROCKIES AND A WEST TO
NORTHWEST FLOW SETTLES IN. BY FRIDAY THIS FLOW BACKS SOME TO
SOUTHWEST TAPPING JUST A TAD OF MOISTURE TO WARRANT THROWING SOME
LOW POPS IN FOR THE HIGHER TERRAIN.

&&

.AVIATION...SOUTHERLY WINDS AT THE SLC TERMINAL ARE EXPECTED TO
BECOME ENHANCED AROUND MIDDAY ONCE AGAIN TODAY. THERE IS ALSO A 20
PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS FROM ABOUT 20Z TODAY
UNTIL 02Z THIS EVENING WHOSE MAIN THREAT WILL BE GUSTY OUTFLOW WINDS
TO 35 KTS OR HIGHER.

&&

.FIRE WEATHER...COOLER AND MORE MOIST CONDITIONS SETTLE INTO THE
REGION TODAY THROUGH THE WEEKEND AS A LARGE CLOSED LOW BRINGS
SCATTERED SHOWERS AND THUNDERSTORMS TO THE REGION. THIS CONVECTION
WILL SHIFT FROM WIND PRODUCING MICROBURSTS TO A GREATER CHANCE OF
WETTING RAIN ESPECIALLY BY TOMORROW. THERE IS ALSO A THREAT OF
LIGHTNING WITH THE STRONGER CONVECTION. SNOW LEVEL WILL GENERALLY
BE BETWEEN 7500 AND 9000 FT.

EVEN OUTSIDE OF CONVECTION...THERE WILL BE WIDER SCALE SOUTHERLY
WIND GUSTS ACROSS CENTRAL AND SOUTHEASTERN UTAH TODAY...ALONG WITH
LOWER RH...FURTHER AHEAD OF THE APPROACHING STORM SYSTEM.

ANOTHER COLD FRONT LATE MONDAY AND TUESDAY KEEPS A COOLER REGIME IN
PLACE. ISOLATED CONVECTION AT BEST...WHILE DRYING NORTHWEST WINDS
BECOME GUSTY WITH THE FRONTAL PASSAGE.

&&

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

$$

SHORT TERM/FIRE WEATHER...ROGOWSKI
LONG TERM/AVIATION...STRUTHWOLF

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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