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fxus65 kpih 160857 

Area forecast discussion
National Weather Service Pocatello Idaho
257 am MDT Tue Jul 16 2019


A cold front will slip through the region today. Expect isolated to
scattered showers and thunderstorms to develop across the central
mountains this afternoon. By late afternoon and early evening, we'll
see isolated showers and thunderstorms develop across the Magic
Valley, snake plain and southern Highlands. Some gusty winds and
small hail are possible, but severe potential likely limited because
of cooler temps today. Most of the convection should die off this
evening with drier and cooler weather likely for Wednesday.

Temperatures will slowly warm as we move through the week with dry
weather likely. Both GFS and European now are latching on to a cold
front arriving on Saturday. This looks like it will be a mainly dry
front, but it will reinforce the cooler weather for the remainder of
the weekend. Models show a ridge developing over the west by early
next week which should bring a return of hot weather to the area.




One more day of isolated to scattered showers/T-storms is expected
this afternoon and eve ahead of a cool front. We have tried to time
out the periods of greatest potential at each taf terminal with
thunderstorms in the vicinity. NAM forecast soundings suggest sufficient instability for a
few stronger storms, but dcape (downdraft instability) values appear
just a bit weaker compared to the past several days at 1,000 j/kg or
less, and the depth of low-level dry air has decreased a bit with
slightly lower cloud bases, so suspect gusty/erratic outflow winds
will be more on the order of 35-45 miles per hour today for most storms instead
of 50+ miles per hour. Small hail will again be possible under stronger cores.
Winds become quite breezy again this afternoon, although predominant
directions don't favor runway crosswind issues. T-storm outflow
boundaries modifying the wind direction will be a concern we will be
monitoring for everyone. Looking ahead to the rest of the week, dry
wx is expected, with again diurnally breezy afternoon winds each day
likely exceeding 10-15 knots, esp at kida/kpih. - Ksmith/Valle


Fire weather...

Isolated to scattered showers and isolated T-storms will be a
concern for one more day, developing generally after 1 PM this
afternoon across the northern half of the forecast area, and after 4
PM elsewhere, gradually moving east through late eve as a cool front
sweeps across the region. Winds will increase diurnally this
afternoon, and may continue well into the eve as the front moves
through, generally out of the west to SW. We are not anticipating the
front itself to bring a massive increase in wind or significantly
modify our temps/relative humidity values on a large scale...the concern for
ongoing fires will be the general increased winds this afternoon/eve
along with lightning and potential for gusty/erratic T-storm outflow
winds of 35-45 miles per hour. Winds are forecast to reach critical thresholds
across zone 410 west of I-15 this afternoon, but slightly more moist
relative humidity values of 18-25% and isolated T-storm coverage preclude the need
for a red flag warning. For Wednesday through the rest of the week,
dry and continued warm wx is expected on a zonal westerly flow. Relative humidity
values should continue to largely run above 15%, but breezy/gusty
winds are expected each afternoon, likely reaching critical
thresholds across portions of zones 410, 425, 411, 422, 475, and
476. We will likely headline this in the fwf this morning. No red
flag warnings/fire weather watches are anticipated at this time
unless the forecast changes. - Ksmith/Valle


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