Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Grand Forks ND
631 am CDT Sat Sep 5 2015
Short term...(today through sunday)
issued at 334 am CDT Sat Sep 5 2015
Concern for today will again be severe thunderstorm and heavy rain
potential. Much like yesterday...strength of storms will depend on
timing of upper wave and cloud cover. The shortwave of the day is
currently (08z) located across western Nebraska and will propagate
to the NE through the day. Expected timing of this feature will
bring forcing into the southern forecast area after 18z...and into the
northern forecast area after 21z. This timing is slightly slower compared
with Friday...which may allow more time for heating. Deep layer
shear will not be much stronger today...and severe potential will
depend on enhanced instability due to heating. As of 08z...low
clouds on the cool side of the surface boundary are advancing to the
south/southeast. Anticipate this south/southeast advancement of
clouds to stall around middle-morning from around Bemidji to Wahpeton
(following the hrrr). Although clouds will likely remain across
much of eastern North Dakota...there is the potential for
clearing across the Minnesota counties. Most cams indicate the
best potential for severe storms will be toward late afternoon
across northwest Minnesota (where forcing will arrive last...providing more time
for heating and greater instability). With precipitable waters near 2 inches
expected...locally heavy rain will also be a concern...although
the entire system should be progressive and limit the coverage of
flash flood potential. Will mention rw+ across northwest Minnesota where stronger
storms are more likely. Considering the many variables
involved...will not yet mention t+.
Cold front will move through the region on Sunday...with
thunderstorms again possible. Timing will determine severe
potential...with most guidance suggesting best chances east of the
region (although Storm Prediction Center did place the far eastern forecast area in a slight
Long term...(sunday night through friday)
issued at 320 am CDT Sat Sep 5 2015
Sunday night-Monday night...cool and dry airmass will be in place.
Cyclonic flow aloft may lead to some showers.
Tuesday-Friday...period begins with zonal flow aloft and an upper
wave moving across the northern tier with associated cold front.
This will bring a chance of convection to portions of northwest
and west central Minnesota. Lwt then moves across Minnesota Thursday night into Friday with
northwest flow pattern setting up for the end of the week. Surface high
pressure over the Dakotas should keep region dry from Friday into
the weekend. Daytime highs will be seasonally cool with maximum temperatures
Thursday and Friday struggling to reach the 70s.
Aviation...(for the 12z tafs through 12z Sunday morning)
issued at 631 am CDT Sat Sep 5 2015
LIFR ceilings affecting most areas early this morning (except fargo).
These ceilings will gradually rise through the day...or move north as
the next system moves toward the region. Used hrrr guidance for
timing of ceilings. Thunderstorms expected this afternoon and evening
across much of the region.