Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Salt Lake City Utah
502 am MDT Wednesday Jul 23 2014
Synopsis...moisture will increase from the south today. Drier air
will return to northern Utah on Thursday and Friday...while the
moister airmass will linger over southern and eastern Utah heading
into the weekend.
Short term (through 06z sunday)...a large high pressure ridge
remains centered over Colorado this morning...keeping much of Utah
and southwest Wyoming under a southwest flow aloft. In the
northern half of the County Warning Area...good warm advection will lead to above
average temperatures this afternoon...including the potential for
the second 100 degree day of the year in Salt Lake City. In
southern Utah...mid- level moisture is streaming into the area
from the Arizona this morning...with increased cloud cover and
light showers already moving over the central and southern
mountains of Utah as of 10z.
This moisture is expected to spread over most of the area by this
afternoon...though the best convective activity will likely be
confined to the southern and eastern portions of Utah. The initial
threat with these storms will be strong gusty winds...as the
boundary layer is still fairly dry. Heavy rain will be possible
later in the day...especially in the far southeastern portions of
the County Warning Area...where precipitable water values as high as 1.2 inches
are expected by 00z Thursday. Gusty synoptic-scale southwest winds
are also possible across much of the forecast area again
today...and combined with the dry lightning will lead to another
potentially hazardous fire weather day.
A Pacific trough is still expected to brush by the northern half
of the County Warning Area on Thursday...pushing cooler and drier air into the
area. Moister air should still linger in the south and east...so
have restricted probability of precipitation to those areas for Thursday and Friday.
Somewhat increased moisture and hot temperatures both look to
return to much of the area through the weekend...as the ridge
quickly rebuilds over the western Continental U.S..
Long term (after 06z sunday)...high pressure will continue to build
over the forecast area into early next week... bringing a
warming...drying trend and a decrease in winds. Temperatures peak in
the north before a shallow cold front oozes into the state late
Monday evening...ushering in a return of moisture to fuel afternoon
storms through the middle of next week.
Aviation...VFR conditions will prevail at kslc through the
taf period...with southeast winds increasing after 16z and becoming
gusty after noon. Winds will most likely switch to northwest late in
the afternoon...though a 20 percent chance exists that this switch
will not occur.
Fire weather...gusty winds and low relative humidity will remain a
concern for much of western Utah today. Additionally...the influx of
moisture into the state has added the potential hazards of dry
lightning and gusty outflow winds from isolated thunderstorms in
portions of southwest...central and northwest Utah.
Gusty southwesterly winds will develop this afternoon across
northwestern Utah. These winds...combined with low humidity...will
combine to create hazardous fire weather conditions...and so the red
flag warning for winds and low relative humidity has been extended through this
evening for zone 478...the northwest corner of Utah.
Moisture spreading northward into the southern two-thirds of the
state today will result in showers and thunderstorms across the
higher terrain this afternoon. Across southeastern Utah where the
moisture is deepest...most storms will be accompanied by wetting
rain. However...across portions of southwest and central
Utah...moisture will be largely confined to the middle and upper
levels...increasing the threat for dry lightning...thus warranting a
red flag warning for portions of southwest and central Utah.
A shallow front will move into northwest Utah Thursday
morning...advancing into central Utah by late afternoon. The primary
impact of this weak feature will be a shift of surface winds to the
north with the front. Winds will remain elevated across northern
Utah Thursday and Friday...but at this time it appears that speeds
will remain just below critical levels.
Utah...red flag warning from noon today to 10 PM MDT this evening for
Red flag warning until 10 PM MDT this evening for utz478.
long term/aviation/fire weather...verzella
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http://weather.Gov/saltlakecity (all lower case)
For frequently asked questions about the area forecast discussion
http://weather.Gov/saltlakecity/general/afd_faqs.Php (all lower case)