Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 201716 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1216 PM CDT Thu Jul 20 2017

.UPDATE...
Issued at 1209 PM CDT Thu Jul 20 2017

See below for an aviation forecast discussion for the 18Z TAFs.

UPDATE Issued at 1020 AM CDT Thu Jul 20 2017

It looks like the fog has dissipated everywhere now, per area
webcams, satellite imagery and surface obs. Gonna let High Temps
ride today. Weak, if any, low level waa in play today as boundary
layer mixing winds eventually settle down out of the southeast
over the entire CWA today, while this area of surface high
pressure over the region shuffles over into the western Great
Lakes region. Boundary layer winds are pretty weak today (less
than 15 knots) and the region from whence air comes is the center
of the Canadian-sourced surface high pressure system. Updates are
out.

UPDATE Issued at 639 AM CDT Thu Jul 20 2017

12z aviation discussion updated below.

&&

.SHORT TERM...(Today through Saturday Afternoon)
Issued at 352 AM CDT Thu Jul 20 2017

Starting to see VSBY drop across the eastern CWA as areas of fog
develop. High amounts of low level moisture remain in place, with
nearly calm winds. Wet soils as well from yesterday`s precipitation.
Had already inserted fog into the forecast several hours ago as many
of the models were suggesting it. Starting to see it pan out as a
few locations across the east are getting down to around 1SM.

Surface high pressure across MN and the eastern Dakotas today will
keep conditions mostly dry under a more stable air mass. Only
exception may be the far southwestern CWA where a few showers or
storms may sneak in as they are closer to the stalled out frontal
boundary off to the south. By late afternoon and especially the
overnight hours, chances for showers and storms will increase again.
Seems as if afternoon convection will be more confined to western SD
closer to the surface trough. Chances will increase across our CWA
during the overnight hours as upper level energy ejects eastward and
a bit of a low level jet develops. Not confident at all on placement
and areal coverage of activity, so will keep broad-brushed POPs in
at this time. Will then be watching the surface trough move into the
eastern CWA Friday afternoon and evening. Sufficient instability and
shear will lead to the potential for strong to severe storms once
again. But, there is still little confidence at this time in regards
to timing and placement of storms.

Saturday looks dry as breezy northwest winds bring in drier air.
Dewpoints will fall back into the 50s but temperatures will remain
warm with highs in the 80s and 90s. Increased winds a bit above
SuperBlend on Saturday given a favorable synoptic scale setup.

.LONG TERM...(Saturday Evening through Wednesday)
Issued at 352 AM CDT Thu Jul 20 2017

The long term begins Saturday night with an upper level ridge axis
over the western U.S. with an upper level low pressure area heading
southeast out of Canada into the Great Lakes region. This puts our
area in cooler northwest flow aloft with corresponding northerly
flow at the surface as high pressure pushes southeast out of Canada
and then to the east of the region through Sunday night. Therefore,
Sunday will be the coolest day in the long term with upper 70s
across the far eastern CWA. These temperatures may end up being even
cooler as we have been a little too warm on some of these cool
pushes of air lately, especially if there is some stratus clouds.
Otherwise, the models all show the western U.S. ridge building into
the central U.S. from Monday into Wednesday bringing very warm/hot
temperatures back to the region. Monday may still be below normal
across the eastern CWA with temperatures warming to just above to
nearly 10 degrees above normal for Tuesday and Wednesday across the
cwa. With the expected upper ridge over the region along with recent
temperatures under these conditions, expect we will have to raise
highs several more degrees as we get closer to this time. More 90s
may be occurring across the CWA for Tuesday and Wednesday. The
region looks to be dry for Saturday night through Monday. There will
then be a few chances of showers/storms for Monday night into
Wednesday as warmer air pushes in from the west.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1209 PM CDT Thu Jul 20 2017

For the time being, the bar is set at good VFR flying weather
forecast for all four terminals through mid-day tomorrow.
Confidence is too low to mention much more than a couple hours of
VCTS at KPIR this evening. Thunderstorms are likely to develop
over the far western Dakotas this afternoon/evening. But, not very
confident that they will ogranize into a convective system and/or
move as far east and south as the KPIR/KMBG terminals overnight.
The region is outlooked for potentially strong storms, though,
through Friday night. Will need to keep a close eye on radar and
short-range guidance trends over the next couple of days.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

UPDATE...Dorn
SHORT TERM...TMT
LONG TERM...Mohr
AVIATION...Dorn



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