Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Grand Forks ND
1142 PM CDT Thursday Sep 3 2015

issued at 1138 PM CDT Thursday Sep 3 2015

Made minor isolated pop adjustments across the far northwest and NE forecast area with
continued weak convection. Expanded some fog potential across the
dvl basin based on short term model guidance. No other changes.

Update issued at 948 PM CDT Thursday Sep 3 2015

Lightning strikes have recently formed along band of weak echoes over
the far northwest forecast area so will introduce some isolated probability of precipitation remainder of the
evening. Earlier echoes have weakened over northern valley into northwest

Update issued at 639 PM CDT Thursday Sep 3 2015

Have added isolated T through the central/northern valley region for
a few hours this evening. Getting a few lightning strikes in small
cluster of mainly altocumulus castellanus. No other changes.


Short term...(this evening through Friday night)
issued at 326 PM CDT Thursday Sep 3 2015

Thunderstorm chances and severity will be the main forecast
problem for the period.

South to southeast winds and hot and humid air continue over the
County Warning Area...with many locations showing dew points in the 70s. Storm Prediction Center
mesoanalysis shows cape values of near 5000 j/kg...but with the
ridge overhead and 700mb temperatures in the 14 c range...a Stout cap is
in place. A few showers have been trying to get going along the
surface trough axis in the Missouri Valley...but cumulus is not very
impressive. Some of the short range models have some convection
entering the Devils Lake basin later this evening. However...many
have been overdoing convection and have storms breaking out over
the Red River valley as of 18z today which didn't happen. With the
cap and in the absence of any strong forcing...will leave this
evening dry. Think that tonight should be fairly quiet...with a
bit of stratus and maybe patchy fog again possible.

Tomorrow...southwesterly flow aloft with a weak shortwave trough
moving into the northern plains. The surface trough axis move in and
extend from the southwestern County Warning Area up towards the northern Red
River valley. The arrival of the shortwave trough along with cape
values in excess of 3000 j/kg should set off some pretty strong
convection by middle afternoon. Deep layer bulk shear values are not
very impressive early on but improve to near 40 kts in the western
counties late in the afternoon. The convective outlook has been
upgraded to a slight risk so included some mention of severe for
Friday afternoon and evening. The shortwave will move off to the
northeast during the night on Friday and the convective activity
will shift to More Lake of the Woods region. There is the
potential for heavy rain with precipitable waters near 2 inches along with
southwesterly flow aloft oriented along a stalled surface boundary.

Long term...(saturday through thursday)
issued at 326 PM CDT Thursday Sep 3 2015

Saturday through Sunday...the southwesterly flow aloft and fairly
active pattern continues. Think there should be a bit of a break
early in the day Saturday before another weak lead shortwave
approaches. Models are in pretty good agreement with lots of
convection Saturday night as the lead shortwave comes have likely probability of precipitation going. The main upper trough does
not enter western ND until late in the day on Sunday...with much
of the precipitation shifting north as a warm front lifts towards the
Canadian border. Temperatures should be cooling off with clouds and
precipitation in the area so kept highs over the weekend into the 70s to
low 80s.

Monday to Thursday...models in fair agreement with cooler and drier
weather as 500mb low north of the County Warning Area lifts to the northeast and
northwest flow aloft develops by the middle of the week. Showers expected
to be exiting the east early Monday with redevelopment of some
shower activity across the north possible Monday afternoon. Thereafter
a dry forecast for most of the area with a slight chance pop in the far
south on Tuesday. With 850mb temperatures around 15c will see maximum temperatures
in the upper 60s to low 70s and lows in the upper 40s to around 50
Monday to Thursday.


Aviation...(for the 06z tafs through 06z Friday night)
issued at 1138 PM CDT Thursday Sep 3 2015

At this time looks like thunder chances slim at any of the taf
sites overnight. St/fog will again be a big challenge. Latest
guidance brings some patchy IFR ceilings into the northern and eastern
half of the forecast area late tonight and included in latest taf sets. Best
T potential tomorrow should be late afternoon first in the dvl
area and into the valley by evening.


Fgf watches/warnings/advisories...


short term...Jr
long term...Jr/jk

National Weather Service Glossary of Abbreviations