309 
FXUS65 KBOI 092011
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
212 PM MDT Mon Apr 9 2018

.SHORT TERM...Tonight through Wednesday...An upper level high
pressure ridge will maintain dry weather tonight. On Tuesday a 
shallow upper level low pressure trough will bring scattered showers 
at lower elevations and more numerous showers over the mountains, 
mainly during the afternoon and evening. Models show only marginal 
instability. The cold front will be weak, and cooling aloft will be 
minor, so we will leave thunder out of the forecast at this time. 
Showers will continue over the central Idaho mountains but end 
elsewhere by late Tuesday night. Snow levels will range from 7000 to 
9000 feet through Tuesday evening then lower to 5000 to 7000 feet by 
Wednesday morning. More precipitation will spread across our area 
during the day on Wednesday ahead of a much stronger Pacific weather 
system. Temperatures will be around 5 degrees above normal on 
Tuesday, then cool to near normal on Wednesday. 

.LONG TERM...Wednesday night through Saturday...Strong upper wave 
passes through the area Wednesday Night. An abrupt cold front looks 
like it will be near the ID/OR border early Thursday morning, and 
push east of the forecast area by mid morning on Thursday. Best 
chances for precip ahead of the front, but still plenty of showers 
behind the front, supporting high PoPs through the day on Thursday. 
Strong winds behind the front will likely make Thursday a very raw, 
cold, windy, showery day. Temperatures likely 15 degrees or more 
below normal. Upper trough then passes overhead on Friday, 
supporting more showers through much of the day. Then ridge builds 
in for much drier Saturday, with temperatures recovering to near 
normal.

Saturday evening through Tuesday morning...The brief relatively 
drier and sunnier conditions will soon give way to cloudy, breezy, 
and moist conditions as a well developed and organized frontal 
system approaches from the west. Models are in agreement with the 
timing and tracking of this system so, expect it to begin entering 
the CWA early Sunday afternoon and continue its eastward track, 
sparking a chance for thunderstorms along the way. The stronger 
activity is expected to be in the eastern locations as daytime 
heating will build up to it's peak in combination additional 
mountain lift. Expect rain to initially cover most areas, with the 
exception of the higher mountains. This will change to higher 
probabilities for snow as lower snow levels move in behind the cold 
front. Winds will also be stronger near the frontal boundary. 
Ridging will once again begin to build in by Tuesday morning, 
improving the weather conditions as the local atmosphere begins 
drying out. Temperatures start out close to normals on Sunday but 
drop to around 5 degrees below normal by Monday.

&&

.AVIATION...VFR increasing clouds aloft overnight. Weakening wave in 
southwest flow Tuesday morning supports some isolated MVFR showers 
west of KMYL-KREO line, then a break midday, with scattered showers 
developing again over Oregon Tuesday late afternoon. Surface winds 
mostly southeast 10-15 kts, but southwest 10-15 over southeast 
Oregon Tuesday afternoon. Winds aloft near 10k ft MSL: becoming 
southwest 25-35 kts.

&&

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

&&

$$

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SHORT TERM...JT
LONG TERM....TB/WH 
AVIATION.....TB