Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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029
FXUS65 KSLC 162212
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
412 PM MDT SAT MAY 16 2015

.SYNOPSIS...A SLOW MOVING LOW PRESSURE SYSTEM WITH AN EMBEDDED
WEATHER DISTURBANCES WILL CONTINUE TO MOVE ACROSS THE NORTHERN
PORTION OF THE REGION TONIGHT. A WEAK RIDGE WILL MOVE IN SUNDAY
INTO MONDAY BUT ANOTHER SYSTEM IS EXPECTED LATER MONDAY INTO
TUESDAY.

&&

.SHORT TERM (UNTIL 06Z TUESDAY)...ALL MODELS ON BOARD WITH MOIST
NORTHWEST FLOW INTO WASATCH FRONT FOR THIS EVENING. IN
ADDITION...THE SHORTWAVE EVIDENT ON THE SATELLITE OVER THE UPPER
SNAKE RIVER VALLEY IN IDAHO...AND PICKED WELL BY MODELS...WILL
MOVE SOUTHEAST THIS EVENING TO ENHANCE PRECIP ACROSS NORTHERN
UTAH. HAVE GONE WITH BEEFY POPS OF GENERALLY OVER 90 PERCENT FOR
THE FRONT AND MOUNTAINS FOR THIS EVENING. HEAVY RAIN IS EXPECTED
AT TIMES DURING THIS EVENING WHICH MAY RESULT IN SOME PONDING OF
WATER ON STREETS. THE MODELS CONTINUE TO KEEP PRECIP GOING THROUGH
THE NIGHT WITH THE GFS HAVING THE BULLS-EYE OVER THE GREAT SALT
LAKE INTO SLC WHILE THE EC AND NAM ARE FARTHER NORTH WITH THIS
BAND. HAVE ALSO INCREASED POPS FOR THE 06-12 TIME PERIOD TO
LIKELY OR HIGHER FROM UTAH COUNTY NORTHWARD. RAIN AMOUNTS OF 0.35
TO 0.75 OF AN INCH ARE EXPECTED OVER NIGHT IN ADDITION TO WHAT HAS
OCCURRED TODAY.

SNOW LEVEL HAS BEEN AROUND 7000-7500 FEET MSL TODAY AND THIS
LOOKS LIKE WHERE IT WILL STAY THIS EVENING WITH A SLOW RISE LATER
TONIGHT. ACCUMULATIONS OF 6-14 INCHES ABOVE 8500 FEET. ROAD
IMPACTS WILL BE MINIMAL BELOW 7500 FT.

FARTHER SOUTH...DRYING IS EXPECTED THIS EVENING AS THE RIDGE AXIS
MOVES IN AND STABILIZES THE AIR MASS BY LATE TONIGHT. HAVE MENTION
OF LINGERING SHOWERS THIS EVENING BUT SHOULD BECOME ISOLATED OVER
ONLY THE HIGHER TERRAIN AFTER MIDNIGHT.

THE RIDGE AXIS AT 500 MB MOVES OVERHEAD SUNDAY AFTERNOON AND WILL
DIMINISH THE CHANCE FOR SHOWERS BUT NOT COMPLETELY AS THE AIR MASS
REMAINS QUITE MOIST WITH PRECIPITABLE WATER IN THE 0.60 TO 0.70
RANGE OVER NORTHERN PORTIONS OF THE CWA. THEREFORE LEFT ISOLATED
SCATTERED SHOWERS IN THE MOUNTAINS AND ISOLATED SHOWERS IN THE
VALLEYS. TEMPERATURES WILL WARM BY ABOUT 15 DEGREES OVER TODAY IN
THE NORTH AND ABOUT 10 DEGREES WARMER IN THE SOUTH.

THE RIDGE MOVES EAST SUNDAY NIGHT DUE TO ANOTHER BOWLING BALL
TYPE OF SYSTEM FOLLOWING THE SAME LANE INTO THE GREAT BASIN
MONDAY. THIS WILL CAUSE SOUTHERLY WIND TO INCREASE SOMEWHAT AND
ALSO BOOST TEMPS SOME AS WELL. HOWEVER...CLOUD COVER IS EXPECTED
TO INCREASE RAPIDLY AS THIS APPROACHING SYSTEM WILL BECOME
NEGATIVELY TILTED CAUSING DIFFLUENCE OVER MOST OF THE CWA WITH
PRECIP BREAKING OUT OVER MOST HIGHER TERRAIN AND SOME VALLEYS AS
WELL. RAIN SHOULD BECOME QUITE WIDESPREAD BY MONDAY EVENING.

.LONG TERM...(AFTER 06Z TUESDAY)...ACTIVE SPRING WEATHER CONTINUES
ACROSS UTAH AND SOUTHWEST WYOMING THROUGH ALL OF NEXT WEEK.
ECMWF...GFS...AND CANADIAN MODELS ARE ALL IN GOOD AGREEMENT THAT
ANOTHER UPPER LOW WILL BE MOVING THROUGH THE SOUTHWEST U.S. DURING
THE EARLY TO MIDDLE PORTION OF NEXT WEEK. UPPER LEVEL LOW OVER
CENTRAL/SOUTHERN CA AT 06Z TUE EJECTS TO THE NORTHEAST AND
ACROSS UT DURING THE DAY AS ANOTHER TROUGH APPROACHES THE CA COAST.
AS UPPER LOW EJECTS NORTHEAST EXPECT GOOD CHANCE OF PRECIPITATION
ACROSS MOST OF UT BUT...ESPECIALLY...ACROSS THE CENTRAL AND NRN
PORTIONS OF THE STATE.

THIS EJECTING SYSTEM IF FOLLOWED BY A VERY BRIEF PERIOD OF SHORTWAVE
RIDGING ON WEDNESDAY WHICH WILL DECREASE THE PRECIPITATION THREAT
AND ALLOW TEMPERATURES TO REBOUND TO NEAR NORMAL. HOWEVER THERE IS
STILL RESIDUAL MOISTURE IN PLACE...SO WILL KEEP MENTION OF
SCATTERED SHOWERS AND THUNDERSTORMS...PRIMARILY ACROSS CENTRAL AND
NORTHERN UTAH.

ECMWF...GFS...AND CANADIAN IN GOOD AGREEMENT THAT YET ANOTHER
UPPER LOW MOVES THROUGH THE SOUTHWEST LATE IN THE WEEK INTO THE
START OF THE WEEKEND. THIS SYSTEM IS EXPECTED TO BRING ANOTHER
PERIOD OF WET WEATHER AND BELOW NORMAL TEMPERATURES TO UTAH AND
SOUTHWEST WYOMING.

&&

.AVIATION...VFR CONDITIONS ARE EXPECTED TO PREVAIL AT THE SLC
TERMINAL WITH CIGS GENERALLY BELOW 5000 FT AGL...THOUGH
OCCASIONAL MVFR CIGS ARE POSSIBLE THROUGH THE EARLY EVENING IN
HEAVIER RAIN. NORTHWEST WINDS ARE EXPECTED TO SHIFT TO THE
SOUTHEAST BETWEEN 02Z AND 04Z...BUT THERE IS A 30 PERCENT CHANCE
THIS WILL OCCUR LATER THAN EXPECTED.

&&

.FIRE WEATHER...AN EXTENSIVE AREA OF RAIN WILL CONTINUE OVER NORTHERN
UTAH TONIGHT AS THE FINAL PIECE OF ENERGY MOVES SOUTHEAST FROM
THE EXITING GOLIATH LOW PRESSURE SYSTEM. RAIN AMOUNTS OF 0.50 TO
1.00 HAVE ALREADY OCCURRED IN THE NORTHERN WASATCH FRONT VALLEYS
WITH 1.50 INCHES IN THE MOUNTAINS WITH 8 INCHES OF SNOW AT HIGHEST
PEAKS OF NORTHERN WASATCH. AN ADDITIONAL 0.40 TO 1 INCH OF RAIN IS
EXPECTED TONIGHT WITH LOCALLY UP TO 1.5 INCHES. FARTHER SOUTH
ISOLATED SHOWERS WILL OCCUR THIS EVENING AND AGAIN SUNDAY...MAINLY
OVER THE HIGHER TERRAIN. SCATTERED SHOWERS SUNDAY IN THE NORTHERN
MOUNTAINS OTHER WISE ISOLATED.

MONDAY WILL START OFF DRY BUT ANOTHER STORM SYSTEM WILL MOVE INTO
THE REGION MONDAY NIGHT THROUGH TUESDAY WITH RAIN AND SNOW LIKELY
ONCE AGAIN. SCATTERED SHOWERS ARE EXPECTED TO PREVAIL THE REST OF
THE WEEK AS TROUGHINESS REMAINS ACROSS THE GREAT BASIN.

&&

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

$$

SHORT TERM...STRUTHWOLF
LONG TERM...GRAHAM
AVIATION...TRAPHAGAN
FIRE WEATHER...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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