Area Forecast Discussion
Issued by NWS Salt Lake City, UT

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
000
FXUS65 KSLC 141500
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
900 AM MDT MON APR 14 2014

.SYNOPSIS...HIGH PRESSURE ALOFT WILL CROSS THE REGION
TODAY...AHEAD OF A SERIES OF PACIFIC STORM SYSTEMS WHICH WILL
CROSS THE NORTHERN GREAT BASIN DURING THE MIDDLE OF THE WEEK.

&&

.DISCUSSION...WATER VAPOR LOOP SHOWS AN AMPLIFIED RIDGE ALONG THE
WEST COAST. AMDAR 400-250MB WIND OBSERVATIONS REVEAL A 80-90KT
CYCLONICALLY CURVED JET OVER THE EASTERN GREAT BASIN AND FOUR
CORNERS REGION. GOES/GPS/RAP/12Z RAOB INDICATE THE PRECIPITABLE
WATER VALUE RANGES BETWEEN 0.03" AND 0.25".

WITH HIGH PRESSURE BUILDING IN TODAY...STABLE CONDITIONS ARE
FORECAST WITH SLACKENING PRESSURE GRADEIENT RESULTING IN DECREASED
WINDS.

THE MOST SIGNIFICANT CHANGE TO THE GOING FORECAST WAS TO INCLUDE
MENTION OF CLOUDS FOR THE WESTERN UINTA BASIN AND PORTIONS OF
SOUTHWEST WYOMING AND THE SAN RAFAEL SWELL PER 11-3.9U SATELLITE
IMAGERY. WHILE GUIDANCE DID A POOR JOB OF RESOLVING THE
STRATUS...OUR HIGH RESOLUTION MODELS INDICATE A LOWERING SUBSIDENCE
INVERSION. GIVEN THE HIGHER SUN ANGLE...PLAYED IT WITH IMPROVING SKY
CONDITIONS THIS AFTERNOON...BUT LOWERED DAYTIME HIGHS.

PREVIOUS DISCUSSION FOLLOWS...

THE SHORTWAVE TROUGH WHICH BROUGHT SHOWERS AND THUNDERSTORMS TO MUCH
OF THE FORECAST AREA OVER THE WEEKEND CONTINUES TO SLIDE OFF TO THE
EAST...AS MID LEVEL RIDGING ALONG THE WEST COAST BEGINS TO BUILD
INLAND. LINGERING CLOUD COVER OVER THE FAR EASTERN CWA WILL CONTINUE
TO DISSIPATE DURING THE REMAINDER OF THE OVERNIGHT HOURS LEADING TO
SUNNY SKIES AREAWIDE FOR MUCH OF THE DAY. WINDS CONTINUE TO DIMINISH
ACROSS THE FORECAST AREA EARLY THIS MORNING...AND THIS TREND WILL
CONTINUE THROUGH THE DAY.

THE AFOREMENTIONED SHORTWAVE RIDGE WILL WEAKEN AS IT CONTINUES
INLAND TODAY...AND EVENTUALLY ACROSS THE FORECAST AREA TONIGHT. AS A
RESULT HIGH AND EVENTUALLY MID LEVEL CLOUDS WILL BE ON THE INCREASE
DURING THE OVERNIGHT HOURS. ANY HIGH CLOUDS DURING THE LATE EVENING
SHOULD NOT BE THICK ENOUGH TO BLOCK OUT THE LUNAR ECLIPSE. THESE
CLOUDS ARE EXPECTED TO THICKEN OVERNIGHT...AND THIS COUPLED WITH
WARMER TEMPERATURES TODAY WILL KEEP ANOTHER HARD FREEZE FROM
OCCURRING ACROSS NORTHERN AND EASTERN UT...THUS NO HEADLINES.

A SHORTWAVE TROUGH FORECAST TO MOVE INLAND DURING THE MIDWEEK PERIOD
IS EXPECTED TO PUSH A COLD FRONT INTO NORTHERN UT LATE IN THE DAY
TUESDAY...WITH THIS FRONT CONTINUING SOUTHWARD THROUGH CENTRAL AND
SOUTHERN UT OVERNIGHT INTO WEDNESDAY MORNING. THE GFS HAS TRENDED
DRIER AND LESS AMPLIFIED WITH THIS TROUGH THAN IT HAD BEEN OVER THE
PAST WEEKEND...AND THIS FRONT NOW LOOKS TO CROSS THE AREA AS A
GENERALLY DRY FEATURE WITH ONLY A SMALL CHANCE OF PRECIPITATION. AS
SUCH HAVE TRENDED POPS DOWNWARD A BIT TUESDAY NIGHT INTO
WEDNESDAY...BUT STILL RETAINED SLIGHT CHANCE WORDING IN THE NORTHERN
VALLEYS AND CHANCE IN THE MOUNTAINS.

CYCLONIC FLOW WILL REMAIN ACROSS THE REGION INTO THURSDAY WITH
TEMPERATURES REMAINING RELATIVELY COOL AREAWIDE...HOWEVER PRECIP
CHANCES APPEAR TO REMAIN MINIMAL DURING THIS TIMEFRAME.

MODEL DIVERGENCE IS LARGER THAN TYPICAL THROUGH THE LONG TERM
PORTION OF THE FORECAST...WITH RELATIVELY LARGE DISCREPANCIES NOTED
BETWEEN THE 00Z GFS AND 00Z EC. GFS ENSEMBLE 500 MB HEIGHT STANDARD
DEVIATIONS ARE LARGE OVER UTAH FROM 00Z FRIDAY THROUGH 00Z
SATURDAY...INDICATING DISPERSION OF THE MEMBERS AS TO WHETHER THE
TROUGH WILL HANG FURTHER WEST LIKE THE OPERATIONAL GFS OR MORE
PROGRESSIVE...REMINISCENT OF THE 00Z EC.

THAT SAID...SHORTWAVE RIDGING IS EXPECTED TO DEVELOP IN THE WAKE OF
THE TROUGH. DEPENDING ON HOW QUICKLY THE TROUGH DEPARTS THE
AREA...RIDGING SHOULD ALLOW FOR A WARM DAY FRIDAY BUT THE EC WOULD
FAVOR A WARMER HIGH THAN THE GFS.

ANOTHER WEAKENING TROUGH WILL MOVE ACROSS THE AREA SATURDAY INTO
SUNDAY. GIVEN THE MODEL TO MODEL INCONSISTENCIES MENTIONED
ABOVE...DID NOT LEAN TOWARD A PARTICULAR MODEL. ADJUSTED POPS A BIT
CLOSER TO CLIMO GIVEN UNCERTAINTY AND THE DISTURBANCES MOVING
THROUGH THE AREA. BOTH MODELS INDICATE THE POSSIBILITY OF A RATHER
LARGE STORM SOMETIME DURING THE WEEK OF THE 20TH. WHILE TOO FAR OUT
TO HAVE ANY REAL CONFIDENCE...SOMETHING TO WATCH OVER THE NEXT
WEEK.

&&

.AVIATION...WINDS AT THE SLC TERMINAL WILL SHIFT TO THE NORTHWEST
BETWEEN 17Z AND 18Z THIS MORNING. VFR CONDITIONS WILL PREVAIL.

&&

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

$$

PUBLIC...ROGOWSKI/SEAMAN/KRUSE
AVIATION...HOSENFELD

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)



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.