Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 041529
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
929 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.


&&

.DISCUSSION...MORNING WATER VAPOR AND H5 ANALYSIS PLACE THE AXIS
OF A HIGH AMPLITUDE RIDGE JUST EAST OVER THE INTERIOR ROCKIES.
UPSTREAM A CLOSED LOW OFF THE CENTRAL CALI COAST CONTINUES TO
SLOWLY CHURN EAST. A WARM SOUTHWESTERLY FLOW ALOFT IN PLACE ACROSS
THE EASTERN GREAT BASIN WILL TREND TO INCREASE OVER THE NEXT 24 TO
36 HOURS AS THIS TROUGH CONTINUES ITS SLOW EASTWARD EVOLUTION.

SHORT TERM WEATHER CONCERNS REMAIN MINIMAL IN THIS PATTERN WITH
SENSIBLE WEATHER REMAINING VERY DRY AND QUITE WARM. H7 TEMP
TRENDS ARE EXPECTED TO INCREASE TO BETWEEN +8 TO +9 C TODAY AND +9
TO +10 C TOMORROW...AND COUPLED WITH DEEP MIXING POTENTIAL WILL
DRIVE VERY WARM TEMPS AREAWIDE. SHOULD REALIZE MAX TEMPS 10 TO 15+
DEGREES ABOVE NORMAL BOTH TODAY AND TOMORROW.

VERTICAL PROFILES DO SUPPORT DEVELOPMENT OF WEAK CONVECTIVE
INSTABILITY AT ABOVE H5.5 TOMORROW AFTERNOON THOUGH LACK OF
ANYTHING MORE THAN ADEQUATE MID LEVEL MOISTURE SHOULD LIMIT
CONVECTION TO SHALLOW HIGH BASED CUMULUS AND A FEW WEAK CELLS OVER
THE MTN SPINES INITIALLY. SURFACE WINDS ACROSS THE WEST LIKELY
REACHING BREEZY LEVELS OUT OF THE SOUTH WITH DEEP MIXING AND THE
CONTINUATION OF INCREASING FLOW ALOFT WITH FURTHER ADVANCEMENT OF
THE TROUGH.

INCREASINGLY DIFFLUENT FLOW ALOFT WILL DEVELOP OVER THE
NORTHERN/EASTERN PORTIONS OF THE FORECAST AREA FOR A PERIOD
THURSDAY NIGHT INTO FRIDAY MORNING. VERTICAL PROFILES BOTH
MOISTEN/STEEPEN AS WELL FRIDAY MORNING INTO THE AFTERNOON. AS
SUCH...WILL DEVELOP THEN MAINTAIN HIGH BASED CONVECTION ACROSS THE
NORTH/EAST THROUGH THIS TIME THOUGH COVERAGE WILL REMAIN LARGELY
SCATTERED IN NATURE. DEEP CONVECTION WILL BECOME INCREASINGLY
MORE LIKELY ACROSS THE NORTHEAST FRIDAY AFTERNOON. DURING THIS
TIME THE UPPER COLD POOL WILL BE WORKING INTO THE SOUTHEAST AS
WELL AIDING TO DRIVE INCREASING SHOWER POTENTIAL AND HIGH
ELEVATION SNOW SHOWERS FROM ROUGHLY I-70 SOUTH DURING THE DAYLIGHT
HOURS...THEN AREAWIDE FRIDAY NIGHT INTO SATURDAY AS THIS COLD POOL
TRANSITIONS OVERHEAD THE FORECAST AREA AS A WHOLE.

CURRENT FORECAST HANDLES THE SHORT TERM WELL AND MADE NO UPDATES
THIS MORNING. PREVIOUS LONG TERM DISCUSSION BELOW...

.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...WINDS AT THE SLC TERMINAL WILL LIKELY BECOME GUSTY OUT
OF THE SOUTH BETWEEN 15Z AND 17Z...WITH ONLY A SLIGHT CHANCE OF
GUSTS REACHING 30 MPH. WINDS ARE EXPECTED TO SWITCH TO THE NORTHWEST
AROUND 20-22Z...BUT THERE IS A 30 PERCENT CHANCE THAT SOUTHERLY
WINDS PERSIST THROUGH THE ENTIRE AFTERNOON.

&&

.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.
&&

$$

MERRILL/SCHOENING/STRUTHWOLF


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VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)


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