Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 211020
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
420 AM MDT MON JUL 21 2014

.SYNOPSIS...A DRY SOUTHWEST FLOW WILL BE OVER THE AREA TODAY
THROUGH TUESDAY. MOISTURE WILL INCREASE FROM THE SOUTH AGAIN ON
WEDNESDAY AND COULD LINGER ACROSS MAINLY SOUTHERN AND EASTERN UTAH
THROUGH THE END OF THE WEEK.

&&

.DISCUSSION...A DRIER SOUTHWEST FLOW HAS BECOME ESTABLISHED ACROSS
THE CWA EARLY THIS MORNING IN THE WAKE OF A SHORT WAVE TROF THAT
LIFTED THRU THE REGION YESTERDAY AND OVERNIGHT. THE LAST OF THE
CONVECTION ASSOCIATED WITH THIS TROF IS EXITING THE NRN CWA AT
THIS TIME.

A LITTLE MOISTURE COULD LINGER ACROSS THE FAR NWRN CWA TODAY WITH
SOME WEAK CONVECTION POSSIBLE AND A CELL OR TWO COULD FORM OVER
THE UINTAS BUT OUTSIDE OF THIS EXPECT A SUNNY DRY DAY CWA WIDE
WITH LOCAL BREEZY SOUTH WINDS IN THE WESTERN VALLEYS.

THE PATTERN REMAINS ESSENTIALLY UNCHANGED FOR TUE WITH MAYBE A
LITTLE AIRMASS WARMING. HOWEVER...ANOTHER WEAK WAVE IS CURRENTLY
WORKING AROUND THE SOUTHWEST SIDE OF THE HIGH CENTERED TO OUR
EAST AND THIS FEATURE IS FORECAST TO LIFT UP THE WEST SIDE OF THE
HIGH TUE NIGHT THRU WED. THIS WAVE WILL BRING MOISTURE BACK INTO
ALL BUT THE NWRN CWA WITH THE DEEPEST MOISTURE EAST OF ABOUT I-15.
EXPECT SHOWERS AND THUNDERSTORMS TO DEVELOP IN THIS MOISTURE WED
POSSIBLY EVEN STARTING UP BEFORE NOON.

ON WED NIGHT INTO THU A FAIRLY DEEP TROF CROSSES THE PACNW AND
LIFTS INTO THE CANADIAN ROCKIES. MODELS HAVE NOT BEEN CONSISTENT
ON HOW DEEP THIS TROF WILL BE A HOW FAST IT LIFTS NORTH. THE
DEEPER SOLUTIONS PUSH A DRY COLD FRONT INTO NRN UT THU AFTN AND
FLATTEN THE UPPER RIDGE WHILE ELONGATING IT E-W ALLOWING A DRY
WESTERLY FLOW TO SPREAD ACROSS THE CWA. THE MORE SHALLOW IDEA
WOULD LEAVE THE RIDGE MORE AMPLIFIED AND ALLOW MOISTURE TO PERSIST
ACROSS MUCH OF THE CWA THRU THE END OF THE WEEK. THE EC HAS BEEN
MORE CONSISTENTLY SHOWING A WEAKER TROF KEEPING MORE MOISTURE IN
PLACE WHILE THE GFS HAS BEEN LESS CONSISTENT RUN TO RUN ON HOW
DEEP THE TROF WILL BE.

HAVE TRENDED FORECASTS TOWARDS THE MORE CONSISTENT EC BUT
CONFIDENCE REMAINS LOW IN THE FORECAST PAST WEDNESDAY.

&&

.AVIATION...WINDS AT THE SLC TERMINAL ARE EXPECTED TO REMAIN
SOUTHERLY THROUGH THE TAF PERIOD...BUT THERE IS A 30 PERCENT CHANCE
THAT WINDS WILL SWITCH TO THE NORTHWEST BETWEEN 21Z AND 00Z.
ISOLATED THUNDERSTORMS WILL LIKELY CONTINUE ACROSS FAR NORTHERN UTAH
THROUGH TODAY...BUT THESE STORMS SHOULD REMAIN WELL NORTH OF THE
TERMINAL.

&&

.FIRE WEATHER...A SIGNIFICANTLY DRIER AIRMASS HAS MOVED INTO MUCH
OF UTAH OVERNIGHT. THIS WILL LEAD TO MUCH LOWER RELATIVE HUMIDITY
VALUES...AS WELL AS RESTRICTING THUNDERSTORM ACTIVITY TO FAR
NORTHERN UTAH. SOUTHERLY WINDS WILL INCREASE ACROSS MUCH OF THE
DISTRICT THIS AFTERNOON. WHILE WIND GUSTS ARE GENERALLY EXPECTED
TO REMAIN BELOW CRITICAL VALUES TODAY...ISOLATED CRITICAL
CONDITIONS ARE POSSIBLE...PARTICULARLY ACROSS PARTS OF WESTERN
UTAH.

WINDS WILL INCREASE A LITTLE MORE ON TUESDAY...MAKING CRITICAL FIRE
WEATHER CONDITIONS MORE LIKELY ACROSS THE WESTERN HALF OF THE STATE.
WITH RELATIVELY LOW CONFIDENCE IN HOW STRONG THESE WINDS WILL
BE...HAVE KEPT THE FIRE WEATHER WATCH IN PLACE FOR
TUESDAY...ALLOWING THE DAYTIME SHIFT TO MAKE THE FINAL DECISION ON
WHETHER A WARNING IS NEEDED. WITH SOUTHERLY FLOW REMAINING IN
PLACE...CRITICAL CONDITIONS COULD ALSO BE POSSIBLE ON WEDNESDAY OR
THURSDAY. ISOLATED THUNDERSTORMS ARE ALSO EXPECTED TO RETURN FOR
PORTIONS OF THE STATE WEDNESDAY AND THURSDAY...ESPECIALLY OVER THE
HIGHER TERRAIN.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
     EVENING FOR UTZ478-492-495.

WY...NONE.
&&

$$

PUBLIC...WILENSKY
FIRE WEATHER/AVIATION...SCHOENING

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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