Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Grand Forks ND
944 am CDT Monday Apr 27 2015
issued at 944 am CDT Monday Apr 27 2015
Clouds have been a bit slower to move into the northwestern
County Warning Area...so adjusted the leading edge over the northern valley into
James River Valley to be partly cloudy. Some lingering patchy fog
so kept some mention in for the next hour or so. Showers are still
over Towner County and short range models do not having it
progressing any further east this morning...so kept probability of precipitation confined
to the far northwestern tier.
Update issued at 648 am CDT Monday Apr 27 2015
Based on current radar trends and short term guidance (rap and
hopwrf)...confined probability of precipitation to the far northwest County Warning Area through the morning.
Otherwise some middle/high clouds continue to advance into the
region...with the southeast portion of the area mainly clear.
Still expect more sun over the southeast half of the area along with the
warmer temperatures...but will have to watch to see how sky trends evolve
Short term...(today through tuesday)
issued at 339 am CDT Monday Apr 27 2015
Rain chances through tonight will be the forecast concern in the
short term...although amounts are expected to be light.
Have included areas of fog through middle-morning from the North Red River back
through the Devils Lake basin...where Devils Lake and Cando have
occasionally dropped to 1/4 mile.
Early am water vapor imagery shows a shortwave trough over Montana...which
will swing east-southeast across the northern plains through tonight. As this
wave swings through...the showers that have mostly been across
central/western ND over the weekend will move east as well. In
the face of downstream shortwave ridging extending through east ND
this morning...do not expect a quick eastward progression of the
precipitation...especially with the upper wave still back west over east Montana
by 12z. Thus...slowed the progression of probability of precipitation a bit more during
the day...and still may be too fast with the progression. The
upper level forcing is not particularly strong and is still back
out over Montana...while it appears the ongoing showers are being
forced by middle-level frontogenesis. Overall...the deep layer
forcing for ascent is expected to weaken tonight...so continued
the trend of gradually lowering probability of precipitation tonight...with the highest
probability of precipitation during the day across the Devils Lake basin. Even to the
west...expect amounts to be on the light side. Highs today will be
warmest from southeast ND up through northwest Minnesota...where less cloud cover is
expected. Today will be a day where cloud trends may impact temperatures.
Some 70s are certainly possible in the warmer areas.
Any remaining showers early Tuesday will end as middle/upper ridging
begins to build in from the west. NAM forecast soundings indicate
a very dry dry atmosphere (pw less than 0.30 inches)...so expect
almost full sunshine on Tuesday with perhaps just a few cirrus. With
gradually warming low level thermal fields...temperatures should climb
well into the 60s.
Long term...(tuesday night through sunday)
issued at 339 am CDT Monday Apr 27 2015
The surface ridge axis will move into the region Tuesday night...which
should allow for temperatures to drop off quickly given the dry air mass.
Some colder locations may be down near the freezing mark by
However...thermal fields continue to warm on Wednesday as the
upper ridge axis continues to shift eastward into the northern
plains. Highs in the middle 70s into the Red River look reasonable...with
most spots at least getting close to 70.
Thursday-Sunday...00z models in good agreement with the overall
pattern. Upper ridge to begin the period will be knocked down by an
upper wave propagating across southern Canada...sending a cold front
and associated showers through the region later Thursday or Friday
(ecmwf faster than the gfs). This should be a relatively low impact
event. Upper flow will be zonal for the remainder of the
period...with any fast moving shortwave capable of producing showers
(timing uncertain). Temperatures will be slightly above normal
Aviation...(for the 12z tafs through 12z Tuesday morning)
issued at 648 am CDT Monday Apr 27 2015
Expect primarily VFR conditions today after morning fog quickly dissipates
at kdvl. A band of showers will slowly move eastward today and
tonight...although confidence is low regarding precipitation timing.
Right now limited -shra mention to kdvl and kgfk. Winds will
remain light through the day and rather variable over the region.
There could be a period of breezier north/northwest winds as a weak surface
boundary pushes from northwest to southeast late this afternoon and tonight.