Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Duluth Minnesota
1217 PM CDT Friday may 22 2015
Short term...(today through saturday)
issued at 359 am CDT Friday may 22 2015
At 330 am...it was very quiet across the Northland. Skies were
clear across the entire region...and winds were calm. Temperatures
ranged from the upper 20s at kcdd to the 30s across the remainder
of the Northland. A few lower 40s were even found near Lake
Superior. Local fog was starting to develop near kpwc and kait.
The focus for today is on high temperatures. With high pressure in
control across the region...we should see full sunshine and high
temperatures generally in the 70s. There is a small chance that we
may need to introduce small probability of precipitation along the extreme international
border region later today. The NAM and the 4km nmm WRF both
indicate that there could be some isolated showers just north of
the border from middle to late afternoon. Will hold off on
introducing probability of precipitation for now but may need to add them if they develop
a bit further south than it currently looks.
Mostly clear skies are in store for tonight...with lows ranging
from the middle 30s to lower 40s.
Saturday is shaping up to be a dry day for much of the Northland.
The exception will be the far south/SW later in the day. The NAM
is most aggressive in bringing quantitative precipitation forecast into the County Warning Area...but the GFS and
the European model (ecmwf) hold any quantitative precipitation forecast off through 00z Sunday. Will continue to
take a slower approach to bringing precipitation into the County Warning Area.
Highs on Saturday are expected to reach the 70s once again.
Long term...(saturday night through thursday)
issued at 359 am CDT Friday may 22 2015
Mild with numerous chances for rain late this weekend into next
week. Much uncertainty remains to the exact pattern...but in general
with an active pattern across the central and northern plains into
the upper Midwest confidence is above normal for beneficial rainfall
across the region.
On Saturday night a ridge over the southeast states and a deep
longwave trough over the western states will result in multiple
middle-level disturbances being ejected into the High
Plains...plains...and eventually into the upper Midwest. Have
adjusted timing of precipitation to delay the best chances until late
Sunday into Monday...with gefs ensemble members supporting a soggy
Memorial Day for the region. With southerly flow at low level across
the Mississippi Valley region rich Gulf moisture will be advected
into the upper Midwest...resulting in precipitable water values 2 to 3 Standard
deviations above normal on Monday. This will result in locally heavy
rainfall...with a widespread half inch of rainfall expected Sunday
night through Monday night...and the potential for up to an inch in
some locations. Precipitation will be mainly stratiform due to stable
thermodynamic profiles at middle/upper levels...but some low level
instability could lead to isolated thunderstorms.
Tuesday through the rest of the week the upper level flow will be
out of the west-southwest which will result in a number of middle-level
impulses moving across the flow. Instability will increase for
Tuesday/Wed/thurs which will bring about better chances for
thunderstorms...but at this point the potential for strong to severe
thunderstorms is very low.
Temperatures remaining mild through the entire period...highs in the
60s to low 70s and lows in the middle 40s to low 50s. Looking
ahead...as we begin to enter the growing season the possibility for
a Spring frost/freeze for this weekend through the end of the month
appears unlikely given the long range guidance.
Aviation...(for the 18z tafs through 18z Saturday afternoon)
issued at 1217 PM CDT Friday may 22 2015
Preliminary point temps/pops...
dlh 68 46 71 47 / 0 0 10 20
inl 72 44 77 45 / 0 10 10 10
brd 72 46 69 50 / 0 0 20 30
hyr 73 43 70 49 / 0 0 10 30
asx 65 43 74 45 / 0 0 10 20