Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 290228
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
828 PM MDT SUN JUN 28 2015

.SYNOPSIS...HIGH PRESSURE WILL REMAIN IN PLACE ACROSS THE REGION
THROUGH THE EARLY PART OF THE WEEK. THE UPPER LEVEL HIGH WILL
SHIFT WESTWARD AFTER MIDWEEK BRINGING A DRIER NORTHERLY FLOW TO
THE AREA. TEMPERATURES WILL REMAIN WELL ABOVE NORMAL THROUGH THE
WEEK.

&&

.DISCUSSION...WATER VAPOR LOOP SHOWS A RIDGE CENTERED OVER THE
EASTERN GREAT BASIN. AMDAR 400-250MB WIND OBSERVATIONS SHOW A
65-95KT ANTICYLONIC JET FROM ALONG THE PACIFIC COAST INTO THE
NORTHERN ROCKIES. GOES/GPS/RAP/00Z SLC RAOB INDICATE THE
PRECIPITABLE WATER VALUE RANGES BETWEEN 0.50" MOUNTAINS AND
SOUTHWEST VALLEYS...TO 0.75"- 1.00" ACROSS THE SOUTHEASTERN AND
NORTHWESTERN VALLEYS.

CURRENT FORECAST IN GREAT SHAPE. CONVECTION WAS QUICK TO DECAY THIS
EVENING UNDER THE CENTER OF THE RIDGE. HAVE UPDATED THE FORECAST TO
REMOVE MENTION FOR THE REMAINDER OF THE NIGHT.

OTHERWISE JUST A FEW TWEAKS TO SKY...TEMPERATURES AND WIND BASED ON
LATEST OBSERVATIONS AND GUIADANCE.

&&

PREVIOUS DISCUSSION...

STRONG UPPER LEVEL RIDGE REMAINS FIRMLY ENTRENCHED OVER THE GREAT
BASIN THIS AFTERNOON. WITH 700 HPA TEMPERATURES OF +18 TO +20
DEGREES C OVER UTAH THE RESULT IS ANOTHER HOT DAY ACROSS THE STATE.
DESPITE LARGE SCALE SUBSIDENCE BENEATH THE UPPER LEVEL
RIDGE...FORCING ASSOCIATED WITH TERRAIN CIRCULATIONS ...PRECIPITABLE
WATER VALUES AROUND .75" AND SBCAPE OF 500+ J/KG OVER THE ELEVATED
TERRAIN...ISOLATED CONVECTION HAS DEVELOPED OVER THE HIGH TERRAIN
WITH THE GREATEST COVERAGE OVER THE SOUTHERN MOUNTAINS. THERE IS
ENOUGH INSTABILITY IN PLACE OVER THE VALLEYS OF SOUTHWEST UTAH THAT
EASTERLY FLOW ALONG THE SOUTHERN PERIPHERY OF THE UPPER LEVEL HIGH
IS ALLOWING SOME STORMS TO PROPAGATE OVER VALLEYS IN SOUTHWEST
UTAH...AS SHOWN BY THE HRRR EARLIER TODAY. PRIMARY THREAT WITH THESE
STORMS WOULD BE STRONG GUSTY WINDS WITH SURFACE-BASED DEWPOINT
DEPRESSIONS OF 50+ DEGREES F ACROSS THE STATE. ANTICIPATE THAT
CONVECTION WILL QUICKLY DIMINISH AFTER SUNSET AGAIN THIS EVENING.

THE UPPER LEVEL RIDGE REMAINS SOLIDLY IN PLACE ON MONDAY WITH 500
HPA HEIGHT AND 700 HPA TEMPERATURE ANOMALIES OF 1-2 STANDARD
DEVIATIONS ABOVE NORMAL. ANTICIPATE ANOTHER HOT DAY WITH HIGHS
SIMILAR TO THIS AFTERNOONS. SO...ANOTHER 100+ DEGREE F DAY ALONG THE
WASATCH FRONT. ALSO...ANTICIPATE A SIMILAR EVOLUTION WITH AFTERNOON
EVENING CONVECTION. THAT IS...ISOLATED STORMS DEVELOPING OVER THE
HIGH TERRAIN PRETTY MUCH STATEWIDE AND THEN SOME STORMS DRIFTING
WEST OFF OF THE TERRAIN INTO UTAHS SOUTHWEST VALLEYS.

ON TUESDAY...UPPER LEVEL WAVE CRESTS THE RIDGE AND MOVES THROUGH THE
NORTHERN INTERMOUNTAIN REGION. THIS FLATTENS THE RIDGE AND ALLOWS
MOISTURE THAT HAS BEEN CIRCULATING AROUND THE PERIPHERY OF THE UPPER
LEVEL HIGH TO SPREAD INTO UTAH. PRECIPITABLE WATER VALUES RISE TO
.80" TO 1" AND WITH INCREASED INSTABILITY IN PLACE EXPECT MORE
SCATTERED COVERAGE OF CONVECTION OVER THE HIGH TERRAIN AND ISOLATED
VALLEY CONVECTION STATEWIDE BY EVENING. INITIAL PUSH OF SLIGHTLY
COOLER AIR DRIFTS INTO FAR NORTHWEST UTAH ON TUESDAY AND TEMPS DROP
BACK A BIT ACROSS THE FAR NORTHWEST. TEMPERATURES ARE AGAIN EXPECTED
TO BE NEAR 100 DEGREES F ALONG THE CENTRAL AND SOUTHERN WASATCH
FRONT. THERE IS THE POTENTIAL FOR THIS TO BE THE FOURTH CONSECUTIVE
DAY OF 100+ DEGREES F AT SALT LAKE CITY WHICH HAS ONLY HAPPENED
THREE TIMES IN THE MONTH OF JUNE GOING BACK TO 1874.

MEDIUM RANGE MODELS ARE CONSISTENT THROUGH THE LATTER PORTION OF THE
WEEK IN RETROGRADING THE MID LEVEL RIDGE WESTWARD INTO NV. THIS WILL
ALLOW A LIGHT NORTHWESTERLY FLOW ALOFT TO OVERSPREAD THE FORECAST
AREA. THIS FLOW WILL ADVECT DRIER AIR INTO NORTHERN UT SLOWLY
SUPPRESSING THE MOISTURE INTO SOUTHERN UT BY THURSDAY...AS WELL AS
USHER IN SOME SLIGHTLY COOLER AIR INTO THE FORECAST AREA. COOLER IN
THIS CASE IS A RELATIVE TERM...AS TEMPERATURES WILL REMAIN WELL
ABOVE NORMAL...HOWEVER SHOULD FALL SHORT OF THE CENTURY MARK ALONG
THE WASATCH FRONT.

DIFFERENCES BETWEEN THE GFS AND EC BECOME EVIDENT LATE IN THE WEEK
THROUGH NEXT WEEKEND...AS THE GFS MAINTAINS A STRONG MID LEVEL RIDGE
ACROSS THE REGION WHICH WOULD ALLOW FOR A WARMING TREND WITH HIGH
BASED MOISTURE QUICKLY RETURNING TO THE FORECAST AREA...WHILE THE EC
OFFERS A MUCH WEAKER RIDGING SOLUTION WITH A DRIER AND SLIGHTLY
COOLER NORTHWEST FLOW OVER MUCH OF THE EASTERN GREAT BASIN. FOR NOW
HAVE INCLUDED SLIGHT CHANCE POPS ACROSS FAVORED TERRAIN AREAS WHILE
MAINTAINING TEMPERATURES WELL ABOVE NORMAL.

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL AT THE SLC TERMINAL THROUGH
THE TAF PERIOD...WITH NORTHWEST WINDS SWITCHING TO THE SOUTHEAST
AROUND 04Z.

&&

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

$$

PUBLIC...ROGOWSKI/GRAHAM/SEAMAN
AVIATION...VERZELLA

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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