Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 180835
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
335 AM CDT Fri Aug 18 2017

.SHORT TERM...(Today through Sunday)
Issued at 335 AM CDT Fri Aug 18 2017

A shortwave trough over SD early this morning will translate east
into MN today ahead of an amplifying upstream impulse and
associated upper-level jet streak which will track from the
eastern Dakotas into the mid-MS Valley by tonight. Forcing for
ascent attendant to the former has fostered a loosely organized
MCS over the mid-MO Valley, which will likely decrease in areal
coverage as it continues southeast across our CWA this morning.
An isolated strong storm is possible, though severe weather is not
anticipated.

A weak cool front will move through the area this afternoon with
winds shifting to northwest with its passage. It appears that
generally weak convergence along this boundary will limit the
potential for the redevelopment of storms later today. High
pressure will build south into the mid-MO Valley tonight,
potentially leading to patchy fog. This is especially the case
across eastern parts of the forecast area where surface winds will
remain light through 12z/Saturday.

A quasi-zonal, mid-level flow pattern is forecast to develop
across the northern tier of states this weekend, supporting
southerly low-level winds, increasing moisture content and warmer
temperatures. The low-level warming/moistening will yield a low-
probability chance of showers and thunderstorms Saturday night
into Sunday.

.LONG TERM...(Sunday night through Thursday)
Issued at 335 AM CDT Fri Aug 18 2017

The primary focus in the long-term period is weather conditions
for the total-solar eclipse on Monday. Latest medium-range model
guidance is consistent in suggesting that a subtropical-branch
shortwave trough over CO Sunday night will be drawn northeast into
the mid-MO Valley on Monday where it will be entrained into a belt
of higher-momentum flow present across the north-central states.
Forcing for ascent associated with this feature will likely foster
scattered clouds and at least an isolated chance of showers and
thunderstorms across southeast NE and southwest IA on Monday
afternoon.

From Monday night into the middle of next week, considerable
amplification of a mid-level trough is forecast from eastern
Canada into the Great Lakes. This upper-air pattern evolution will
support the movement of a cold front through the forecast area
Monday night into Tuesday when a good chance of measurable
precipitation will exist. The cold front will usher a cooler,
continental air mass into the region with near or slightly below-
normal high temperatures expected through the middle to latter
part of the upcoming week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1117 PM CDT Thu Aug 17 2017

Radar mosaic was showing a line of TSRA extending from SE SD into n-cntrl
Neb quickly moving to the SE. Feel somewhat confident
enough...given radar trends...to go with prevailing TSRA at KOFK
between 08Z-10Z with conditions quickly improving to VFR. As far
as KOMA/KLNK...appears that the SRN flank of intense storms may
miss both TAF sites with areal coverage of convection relatively
small. Therefore will go with VCTS between 11Z-15Z. VFR
thereafter.


&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&

$$

SHORT TERM...Mead
LONG TERM...Mead
AVIATION...DEE



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