Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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024
FXUS65 KSLC 040915
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
315 AM MDT WED MAY 4 2016

.SYNOPSIS...HIGH PRESSURE WILL BRING A WARMING TREND THROUGH
MIDWEEK. THE NEXT PACIFIC TROUGH WILL ADVANCE INTO THE GREAT BASIN
LATE IN THE WEEK.

&&

.SHORT TERM (THROUGH 18Z SATURDAY)...
WATER VAPOR LOOP SHOWS RIDGING BEGINNING TO SLIDE TO THE EAST AS
A SPLITTING STORM NEARS THE WEST COAST. AMDAR 400-250MB WIND
OBSERVATIONS PLACE A CYCLONIC 90-125KT JET MAGNITUDE OVER THE
EASTERN PACIFIC. GOES/HRRR/00Z KSLC RAOB INDICATE THE PRECIPITABLE
WATER VALUE RANGES FROM 0.05"-0.15" MOUNTAINS TO 0.30"-0.45" MOST
VALLEYS.

A DRYING AND WARMING TREND IS FORECAST TO CONTINUE TODAY AND
TOMORROW WITH A RIDGE OVERHEAD.

SOUTHERLY WINDS BEING TO GUST LATE THIS AFTERNOON AND STRENGTHEN
TOMORROW IN ADVANCE OF A SPLITTING PACIFIC TROUGH. GUSTS MAY NEAR
ADVISORY LEVELS ACROSS A FEW WESTERN VALLEYS TOMORROW AFTERNOON AS
700MB WINDS INCREASE TO 30-35KTS WITH 8-10MB/6HR PRESSURE FALLS
THOUGH GRADIENT DOESNT LOOK TOO STRONG YET.

EXPECT ISOLATED CONVECTION TO DEVELOP ON THE HIGHER TERRAIN THURSDAY
AFTERNOON. SHORT RANGE ENSEMBLES SUGGEST INCREASING INSTABILITY
PERSISTING THROUGH THURSDAY NIGHT AND FRIDAY MORNING PARTICULARLY
ACROSS EASTERN AND NORTHERN ZONES. SNOW LEVELS LOOK TO BE 8-10KFT IN
THE WARM SECTOR.

CONVECTION FRIDAY NIGHT INTO SATURDAY WILL BE DRIVEN BY ARRIVAL OF
COLD POOL ALOFT ACROSS THE SOUTHERN ZONES THOUGH SREF INDICATES
RIBBON ON BEST INSTABILITY TO REMAIN NORTH AND EAST OF THE CLOSED
LOW. THUS HAVE PRETTY BROAD BRUSH OF SCATTERED CONVECTION IN THE
FORECAST AT THIS TIME WITH CLOUDS BEGINNING TO FILL IN.

.LONG TERM (AFTER 18Z SATURDAY)...
THE MODELS REMAIN QUITE SIMILAR THROUGH THE WEEKEND PORTION OF
THE EXTENDED PERIOD WITH THE OVERALL SYNOPTIC SCALE PATTERN.
HOWEVER THERE ARE SUBTLE DETAILS THAT THE MODELS DIFFER ON AND
BECAUSE OF THIS CAN NOT FULLY LEAN IN FAVOR OF ONE MODEL OVER
ANOTHER. THEREFORE HAVE BASICALLY KEPT THE CURRENT PRECIPITATION
FORECAST OF CHANCE OR LIKELY IN THE MOUNTAINS AND SLIGHT CHANCE OR
CHANCE IN THE VALLEYS. WITHOUT ANY SIGNIFICANT LIFTING MECHANISM
HAVE OPTED TO GO WITH SOMEWHAT HIGHER POPS DURING THE AFTERNOON
AND EVENINGS AND LOWER POPS AT NIGHT AND MORNING THROUGH SUNDAY
NIGHT.

TEMPERATURES WILL LOWER TO NEAR NORMAL ACROSS NORTHERN PORTIONS OF
THE CWA WHILE BELOW NORMAL TEMPERATURES BY 5 TO 10 DEGREES ARE
EXPECTED ACROSS THE SOUTHERN PORTIONS WHERE THE CORE OF THE COLD AIR
ALOFT WILL TRACK.

HAVE INCREASED POPS FOR SUNDAY EVENING OVER NORTHERN UTAH AS THE GFS
AND EC BOTH SHOW A 700MB TROUGH AXIS ROTATING SOUTHEAST. THE EC IS
STRONGER WITH THIS FEATURE...WITH PRE-FRONTAL LIFT AND THE STRENGTH
OF THE NORTHWEST WINDS AND SUBSIDENCE BEHIND THE TROUGH AXIS. HAVE
LEANED TOWARD THE EC WHICH THE PREVIOUS FORECAST ALREADY SIDED WITH
WITH MORE DRYING OVER THE WESTERN VALLEYS FOR MONDAY AFTERNOON.

SOME MOISTURE LINGERS OVER THE MOUNTAINS INTO TUESDAY BUT NOTHING
SIGNIFICANT. BOTH THE GFS AND EC HINT AT SOME MOISTURE MOVING
NORTHWARD INTO SOUTHWEST UTAH WEDNESDAY. NOT OVERLY IMPRESSED WITH
THIS BUT THERE IS AN ENTRANCE REGION TO THE JET OVER SOUTHWEST UTAH
AT THIS TIME SO COULD NOT IGNORE. LOW POPS OVER SOUTHWEST UTAH
WEDNESDAY AFTERNOON FOR MAINLY MOUNTAINS AND ADJACENT VALLEYS FROM
ABOUT I-70 SOUTHWARD.

&&

.AVIATION...VFR CONDITIONS EXPECTED AT SLC TERMINAL THROUGH THE TAF
PERIOD. SOUTHEAST WINDS ARE EXPECTED TO BECOME ENHANCED AFTER 14 AND
15Z THIS MORNING WITH GUSTS NEAR 20 KTS. WINDS SHOULD SHIFT TO
NORTHWEST BETWEEN 20 AND 22Z BUT THERE IS A 30 PERCENT CHANCE THAT
WINDS WILL REMAIN SOUTHERLY THROUGH THE AFTERNOON AND EVENING.

&&

.FIRE WEATHER...A WARMING/DRYING TREND CONTINUES THROUGH TOMORROW.
SOUTHERLY WINDS BECOME GUSTY WITH AREAS OF LOW RH WEDNESDAY AND
THURSDAY AHEAD OF A SPRING STORM WHICH ARRIVES FRIDAY. FRIDAY
THROUGH THE WEEKEND APPEAR TO BE COOLER AND MORE MOIST WITH
SCATTERED SHOWERS AND THUNDERSTORMS.


&&

.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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