Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 220258

Area Forecast Discussion
National Weather Service Grand Forks ND
958 PM CDT THU JUL 21 2016

Issued at 958 PM CDT Thu Jul 21 2016

No significant changes made this update period.

UPDATE Issued at 629 PM CDT Thu Jul 21 2016

Update not necessary, forecast on track.


.SHORT TERM...(This evening through Friday)
Issued at 332 PM CDT Thu Jul 21 2016

Temperatures and if we get any fog formation early tomorrow will
be the main challenge as we get a brief break between systems.

West to northwesterly flow aloft continues over the Northern
Plains, with a decent shortwave trough moving through Canada but
staying to our north. Surface low pressure to the east and south
will move further away, allowing weak high pressure to build in.
Light and variable winds under the high and recent rainfall will
set up the possibility of patchy ground fog. However, some
slightly drier air should be moving in from the west. With lows in
the low to mid 60s and lower dew points large areas with 100
percent RH are not likely at this point. Think that if anything
forms it will be extremely shallow and patchy so will keep
mention out of the grids for now.

Tomorrow, the upper ridge builds in briefly as the next trough
digs into Montana. Winds will increase out of the north and then
east tomorrow afternoon as a trough of low pressure gets going in
the lee of the Northern Rockies. Not much change in air mass so
highs again will get into the 80s to low 90s. The domestic models
have moisture and instability pooling in southwestern ND tomorrow,
and this fits with the CAMs showing some cells starting to fire in
that area late Friday afternoon. Think the best chances for precip
in our area will be after 00Z Saturday, so will keep the afternoon
hours dry for now.

.LONG TERM...(Friday night through Thursday)
Issued at 332 PM CDT Thu Jul 21 2016

Friday night through Saturday night...There seems to be some model
consensus in bring a weak lead shortwave out into the Dakotas
Friday night, with the main upper trough coming into the area
Saturday and Saturday night. With the weak lead shortwave and warm
air advection out ahead of the main surface low along the MT/ND
border, there should be plenty of upper support for thunderstorms
late Friday night and into Saturday morning. Elevated CAPE values
are around 1500 J/kg over the western counties but deep layer
bulk shear is up around 50 kts. Another overnight round of severe
will be possible, so have fairly high POPs going late Friday night
into Saturday morning. Depending on the exact timing of the early
convection and when the main surface trough axis comes out,
another round of severe will be possible Saturday afternoon and
evening as a cold front begins to push through. Timing is still
uncertain and much depends on how Friday night plays out. But have
storms continuing through much of the night and then tapering off
in all but the far northeast after midnight Saturday night.

Sunday to Thursday...Models in good agreement with the overall
flow maintaining an active pattern across the Northern Plains after
a couple quiet days Sunday and Monday. Thunderstorm chances will
increase again Tuesday through Thursday with mid level troughs
interacting with the ever present instability inducing high SFC
dewpoints of 65 to 75F. Seasonal temperatures will prevail with
highs in the 80s and lows in the 60s.


.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 629 PM CDT Thu Jul 21 2016

VFR conditions expected through the period with light winds. Will
monitor fog potential through the evening although available
guidance not very favorable.


.FGF Watches/Warnings/Advisories...


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