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Area forecast discussion 
National Weather Service Grand Forks ND
1255 PM CDT Thursday Sep 18 2014

Update...
issued at 1249 PM CDT Thursday Sep 18 2014

Afternoon forecast on track as just a finger of stratus left on
visible satellite imagery impacting the ND side of the Red River. Temperatures
warming rapidly with sun...up 10 degrees at Crookston in the past
90 min. Still see no reason for adjusting maximum temperatures so will leave
them in the 70s valley and west with upper 60s in the Minnesota pines.

Update issued at 936 am CDT Thursday Sep 18 2014

Challenges for this mornings update includes low stratus and
dissipating fog. Stratus deck along and east of the Red River will
erode as pressure gradient increases between departing Great
Lakes surface high and developing trough of low pressure in the High
Plains. This mixing will quickly erode the stratus in the next
couple of hours. The rap and hrrr indicate this in their latest
solutions. Adjusted the sky grids and temperature curve through early
afternoon and kept the inherited maximum temperatures the same.

&&

Short term...(today through friday)
issued at 400 am CDT Thursday Sep 18 2014

The main challenge will be convective chances later today through
Saturday. Models remain in very good overall agreement...with a
few minor differences.

For today...there will be a band of clouds at least this morning
affecting areas along and east of the valley. There is also some
patchy fog with this stratus...and will add some for early
morning. This stratus could hold temperatures down once again if they do not
erode until middle/late afternoon...so temperature forecast will be tricky
for some areas where clouds hold. It should remain dry through 00z
Friday...with southeast winds increasing this afternoon.

For tonight...the chances for showers and storms should develop
from west to east through the night. It could be windy for much of
the night with good mixing at least this evening...and 30-40kt to
mix. A developing inversion should keep stronger winds from mixing
down though. A strong cap will be in place much of the night...but
the cap near 850mb should erode late with the best forcing and middle
level moisture advection in the north.

On Friday...there could be a few bands of showers and storms...one
in the morning in the east...and another later in the afternoon in
the west. Given these tough to time waves...we will continue with
mainly low end chance probability of precipitation for showers and storms. It should be
warm with westerly surface winds and at least some sunshine...with
around 80 in the west and low 70s east.

Long term...(friday night through wednesday)
issued at 400 am CDT Thursday Sep 18 2014

For Friday night...expect continued chances for some convection...as
as a surface boundary moves through the area. The best chance for
measurable rain will occur in the northern areas closer to surface low track.

On Saturday...a strong speed maximum will enhance large scale
divergence aloft. This coupled with precipitable waters still near 1 inch in the
north...and some lingering instability should mean mainly shower
chances and perhaps a rumble of thunder. The best chance for
precipitation could occur late in the morning/early afternoon as
shortwave moves through. Cool advection will move in Sat afternoon
with northwest winds increasing to at least 20kt in the northwest...along with
adiabatic soundings up to around 700mb with 35kt to mix. Temperatures
will be cool to around normal...with more clouds and cold air advection by
afternoon.

For Sat night...it should be mainly dry with perhaps a lingering
shower mainly in the northeast.

Long wave ridge axis remains over western Canada through much of the
period. By day 7 zonal flow is across Canada. The GFS is faster than
the European model (ecmwf). Will prefer the slower European model (ecmwf).

Upper low off the West Coast is forecast to move into the plains by
Wednesday. Will add probability of precipitation for Wednesday.

Temperatures were decreased by a degree for sun and increased a degree for
Monday...Tuesday and Wednesday compared to yesterdays run.

&&

Aviation...(for the 18z tafs through 18z Friday afternoon)
issued at 1249 PM CDT Thursday Sep 18 2014

IFR cloud cover rapidly eroding with VFR conditions arriving at valley
airfields. Gradient wind from south starting to increase
now...expect 15 to 20 kts g25 everywhere by middle afternoon. Rain shower/thunderstorm to
approach overnight into Thursday...sufficiently low pop warrants
omission from tafs at this time.

&&

Fgf watches/warnings/advisories...
ND...none.
Minnesota...none.
&&

$$

Update...jk
short term...dk
long term...hoppes/dk
aviation...wjb

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