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Area forecast discussion 
National Weather Service Grand Forks ND
1133 PM CDT Wednesday Oct 1 2014

Update...
issued at 1133 PM CDT Wednesday Oct 1 2014

Clouds are decreasing a little faster than expected west of the
Red River valley...which will slowly spread into the east as well
late. There will still be some patchy middle and high clouds around
but not too much. Rest of forecast looking good.

&&

Short term...(this evening through Thursday night)
issued at 310 PM CDT Wednesday Oct 1 2014

A very complex forecast for later Thursday night and Friday...with
accumulating snow becoming a possibility for at least the north.
The NAM is the most robust with the upper wave...cold air and snow
accumulating potential. The GFS is quicker and would give some
snow to the north but minimal accumulation. The European model (ecmwf) has not come
in yet today...and it was the first to portray this snow
potential. The sref is more in line with the NAM with snow
potential for the north with slower...more potent and closed 700mb
low. With all this said...will issue an Special Weather Statement for the Devils Lake
basin for accumulating snow potential later Thursday night into
Friday...with strong north winds also behind cold front. Given it is
so early in season...many details to Iron out.

For tonight...it should be mainly dry with perhaps an early shower
in the far east. Temperatures won't get too cold and remain above normal
though given relatively high dewpoints.

On Thursday...a strong shortwave in northwest flow drops into southern
Manitoba by late afternoon. Highs should warm into the 60s for
most...and there will be a ribbon of instability in the Red River
valley Thursday afternoon...with convective available potential energy around 500 j/kg.
Therefore...will maintain the shower and thunder chances along and
west of the valley Thursday afternoon.

For Thursday night...this is where the forecast becomes challenging. A
strong cold front will push through the region from northwest to southeast.
850mb temperatures will cool below 0c in most areas by 12z Friday...with
large scale lift and rain mixing with or changing to snow in the
dvl basin after 06z Friday. Strong northwest winds will also develop with
50kt to mix from 925mb by 12z Friday along and west of the valley.
There is the potential for snow accumulation in the dvl basin into
the northern valley late Thursday night if snow rates become high
enough. Studies have shown that snow accumulation is possible this
time of year...if snow rates are high enough. This occurred on
October 4 2012 when there was snow accumulation on the northern
valley.

Long term...(friday through wednesday)
issued at 310 PM CDT Wednesday Oct 1 2014

On Friday...it will be very windy with at least advisory level
winds from 30 to 40 miles per hour with gusts to 50 miles per hour not out of the
question in the valley. In addition...the NAM depicts a
deformation rain/snow band that would be all snow according to
soundings in most areas. Given that the GFS is slightly
warmer...will confine snow mention to the dvl basin and gfk and
points north. There will be nearly 50kt to mix though...and if
snow rates become high enough we may need winter weather headlines
and will need to keep a close eye on this early season storm
potential. Temperatures could fall into the middle/upper 30s for some areas
by Friday afternoon...depending on timing of strongest cold air advection.

On Friday night...there could be some lingering light rain/snow in
the east...but for now will continue with dry forecast but
something to monitor. Temperatures should get cold and we could have a
widespread frost/freeze for sure.

For Saturday...it should be dry and cool after a frosty start.
There could be some increasing clouds late in the north ahead of a
weak shortwave in northwest flow aloft.

For Sat night through Wednesday...this long term discussion will focus
on the 12z GFS as there are issues with todays 12z European model (ecmwf) coming
in. See previous discussion for details on 00z European model (ecmwf). The GFS keeps a
Hudson Bay area/western Ontario upper low in place for much of the
discussion. This along with a Canadian rockies ridge keeps the
northern tier of the Continental U.S. In a northwest flow pattern through day 6 and
7...when the pattern gradually becomes more zonal. A series of
waves from the upper low will keep periods of light probability of precipitation across
north central Minnesota...while the Dakotas remain dry. Highs and
lows will generally be in the 50s and 30s, respectively, as the
pattern limits any strong warmup from the cold air mass coming in
during the short term.

&&

Aviation...(for the 06z tafs through 06z Thursday night)
issued at 1133 PM CDT Wednesday Oct 1 2014

With the clouds decreasing now expect to start Thursday off with a
little more Sun. Morning heating and cooling temperatures aloft should
lead to late morning or early afternoon scattered-broken cumulus. Cold
front should impact kdvl by middle afternoon and kgfk/kfar by around
00z Friday. Some weak instability along the boundary but think
thunder will be more isolated...so will just mention showers or
vcsh in the tafs. Bigger impact will be increasing west to northwest
winds behind the front.

&&

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

$$

Update...godon
short term...dk
long term...dk/speicher
aviation...godon

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