Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Boise Idaho
844 PM MDT sun Jul 5 2015
Discussion...strong thunderstorm has been slowly tracking due south
along the western Harney County border this evening. Storm went right
over Wagontire/or with .53 inch of rainfall in one hour...along with
49 miles per hour maximum wind gust. The area is in poor radar coverage but
lightning data and the duration of the storm show how strong it is.
Elsewhere...a band of showers set up this afternoon from around
Warm Lake/Idaho through Caldwell/Idaho to Rome/or...and cloud cover held
temperatures down considerably over southwestern Idaho and southern Malheur co/or. Late
today the band of showers moved southeast through the upper Treasure
valley where up to .10 inch of rain was recorded...although Boise
only received a trace of rain. Thunderstorms were also observed along
the Nevada border with Twin Falls and Owyhee counties this afternoon
and evening...but weaker than the Harney County storm. Fewer clouds
and showers will allow valley temperatures to climb back into the 90s Monday
but no more 100+ days for at least a week.
Aviation...VFR. Scattered to broken middle and high level clouds.
Isolated thunderstorms this evening mainly in western Harney County
and near the Idaho-Nevada border. Thunderstorms redeveloping Monday
afternoon across southern Harney and Malheur counties...south of the
Snake River Valley...and over the west central Idaho and Boise
Mountains mainly east of kmyl and Idaho City. Surface winds...
variable 5-15 kts. Winds aloft...west 10-20 kts up through 10k feet
mean sea level.
short term...tonight through Wednesday...persistent band of
showers extends from north of kreo through the lower Treasure
valley and into the northern Boise Mountains as of 3 PM MDT. We expect this
band to sag southeast through the remainder of the afternoon and
into the evening...and have increased probability of precipitation accordingly. More
significant convection will exist to the south and east of that
line where partial clearing has occurred this afternoon. A front
is moving in from the northwest...leading to some clearing in the northwest
portion of the County Warning Area...generally Baker County and vicinity. An upper
trough is going to continue moving by to our north overnight...
leaving a ridge axis which will extend from southeast Nevada into western Oregon
by tomorrow morning. This will leave US with a lower chance of
showers and storms for Monday and Tuesday. We will see this basic pattern
extend into Wednesday. By Wednesday afternoon...an upper low off the coast of
California will begin to move inland...narrowing the ridge axis and
increasing moisture flow from the south into the southern portion of
the area. Temperatures will be a few degrees above normal through the
short term. Skies will see some clearing late tonight into
tomorrow...then remain mostly clear apart from isolated afternoon
and evening convection through midday Wednesday. Clouds will increase
from the south Wednesday afternoon.
Long term...Tuesday night through Sunday...moisture will increase
across the region ahead of an upper low pressure system off the
coast of California beginning Wednesday night. The upper low weakens
becoming an open trough as it moves into the Great Basin on
Thursday. Moisture area of this system will push north into the
forecast area for afternoon showers and thunderstorms mainly over
the higher terrain. The weak upper level trough will move across
the region Friday into Saturday allowing enough forcing for showers
and thunderstorms across the entire forecast area. The region will
remain under southwesterly flow Sunday with an upper level ridge to
the southeast and a deepening trough to the northwest. Temperatures
will gradually cool to normal by Friday and remain near normal
through the weekend.
previous short term...snow pellets
previous long term....jds