Weather Service Report


246 
FXUS65 KBOI 231656
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
956 AM MST Sun Feb 23 2020

.DISCUSSION...Clouds are spreading into the region from the
northwest this morning, ahead of an upper level system that will
drive a cold front through the region later today. Latest
estimate is that the front will enter Baker County and southeast
Oregon mid-afternoon, get into southwest Idaho late afternoon and
early evening, and exit the western Magic Valley before midnight.
Still expecting 1 to 3 inches of snow above around 5000 feet, with
just a few hundredths of rain in the lower elevations. There is
some instability with this system, and a few showers could become
strong this afternoon along and just behind the front. These
isolated showers could produce up to a tenth of an inch of rain,
possibly mixed with graupel, but coverage will be minimal. No
changes to the forecast at this time.

&&

.AVIATION...VFR this morning. Areas of MVFR and local IFR with 
mountain obscuration associated with a cold front crossing the 
region this afternoon. Showers this afternoon across Baker County 
Oregon and the Central Idaho mountains with snow levels 3000-4000 
ft MSL. Scattered showers spreading south across SW Idaho 
following the front this evening, with snow levels 3500-4500 ft 
MSL. Most showers across SW Idaho ending by 24/06z, with showers 
and mountain obscuration continuing over the West Central 
mountains overnight. Surface winds: generally SE 5-15 kts, 
becoming W to NW 10-20 kts behind the cold front with gusts up to 
35 kts. Winds aloft at 10k feet MSL: W 35-55 kts, becoming NW 
after 24/06z.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Tuesday night...Upper level trough and
associated cold front reaching the Pacific Northwest coast this
morning will quickly move east reaching the forecast area later
this afternoon. Convective showers will follow frontal passage
with snow levels initially around 4000 to 5000 feet, accumulating
snow will be confined to the mountains and higher foothills. 
Amounts will be generally light, with 1 to 3 inches expected. 
Rainfall in lower elevations will be 0.05 inches or less. Stronger
showers could produce a brief period of graupel. Winds along and 
behind the front will be generally from the northwest 10 to 20 
mph with gusts to 30 mph. Even higher gusts are likely in 
southeast Oregon, with gusts above 40 mph. Colder but dry
conditions follow the front as a ridge begins to push east over
the region. Temperatures will be just above normal today falling
about 4 degrees below normal for Monday. 

LONG TERM...Wednesday through Sunday...An upper ridge will build 
into the region through Friday, resulting in dry conditions and a 
warming trend with temperatures 5-10 degrees above normal by Friday. 
Southwest flow aloft will become increasingly moist through the 
weekend as the next upper trough enters the Pacific Northwest. 
Shower chances will favor the higher elevations on Saturday with a 
chance for all areas Saturday night through Sunday. Snow levels are 
expected to remain above lower valley floors. Temperatures will 
remain above normal, with slight cooling on Sunday.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.

&&

$$

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DISCUSSION...SP
AVIATION.....AL
PREV SHORT TERM...JDS
PREV LONG TERM....BW

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Western Regional Climate Center, wrcc@dri.edu