Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 190841

Area Forecast Discussion
National Weather Service Omaha/Valley NE
341 AM CDT FRI AUG 19 2016

.SHORT TERM...(today through Sunday)
Issued at 340 AM CDT FRI AUG 19 2016

Severe weather threat and areal coverage of storms is the primary
problem today and tonight.

Cold front has continued to make progress into the area early this
morning, extending from south central NE through northwest IA at
08z. A few showers or sprinkles have developing across mainly
western IA, with the remainder of the forecast area dry at this
time, although a few spotty showers could linger and affect the
eastern I80 vicinity early this morning. There are a couple of
features on water vapor of interest that will help drive our
weather and Pops today. The first is a weak vort swirl in central
NE, which is producing a few thunder showers. This area of
precip should clip northeast NE this morning, so will have Pops
there, but nothing at all in southeast NE and southwest IA. The
second area of stronger convection is developing across the
western High plains in response to the forcing for ascent from
the trough across the central Rockies. This trough eventually
moves into the mid Missouri River valley and brings our severe
weather threat later this afternoon and evening with a substantial
increase in Pops by late afternoon. Temps today will vary widely
across the forecast area, just in the lower 70s in northeast NE,
but still near 90 in southeast NE and southwest IA.

Regarding severe threat, instability substantially increases, with
CAPE values 2000-3000 J/Kg this afternoon and early evening. Bulk
0-6km shear of 25 to 35 knots should easily support multicell
development, although some of the cells could be supercellular
early on in the event when discrete development may occur along
the cold front. PW values increase to 1.75-2.25" with the Nam the
higher model, thus locally heavy rain will be possible with any
cells. Large hail threat and strong wind initially in the event,
transitioning to damaging winds as a cold pool develops and system
becomes more linear. Currently have 1-1.5" in the areal average
QPF forecast grid. WPC has placed most of eastern NE in a marginal
risk of excessive rainfall. No plans for any flash flood watch
today, with 3 hourly flash flood guidance 1.9-3.0". Storms have
proven recently to be very efficient rainers though in these high
PW environments, so it`s something to watch closely, especially if
training of storms develop.

Whatever does develop by 5-7pm will continue to make eastward
progress through the evening, but severe threat transitions east
of the forecast area by mid to late evening. Rain chances continue
though behind the initial severe threat overnight as we remain
under the influence of the northern stream upper trough.

Saturday will be much cooler with breezy northwesterly winds.
Upper trough will be moving through the region. Models hint that
there could be isolated lingering showers especially across the
northeastern half of the forecast area Saturday morning. Highs
Saturday only in the 70s.

Dry conditions Saturday afternoon through Sunday with abundant

.LONG TERM...(Sunday night through Thursday)
Issued at 340 AM CDT FRI AUG 19 2016

Dry Monday with temps back into the mid 80s. Rain chances increase
once again by Tuesday through Thursday as a series of upper level
disturbances move into the area, although the models are
disagreeing on the details of the placement on Tuesday. A new cold
front materializes Wednesday and pushes into the area, with
continue rain chances, and slightly cooler temps in the lower 80s
Wednesday, and upper 70s to lower 80s Thursday.


Issued at 1151 PM CDT THU AUG 18 2016

Scattered showers and thunderstorms will increase across eastern
Nebraska through the TAF period as a cold front settles into the
area. The front should reach KOFK before 12Z, with MVFR cigs
settling in behind. Scattered thunderstorms are possible through
16Z, with another round developing in the early afternoon. Storms
will likely hold off at KLNK and KOMA until after 18Z when a line
of storms moves in from the west. Attendant MVFR to IFR cigs/vsbys
will accompany any storms. Then MVFR cigs in scattered showers are
forecast behind the main batch of storms, generally from about 02Z
to the end of the TAF period.


.OAX Watches/Warnings/Advisories...


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