Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 152011

Area Forecast Discussion
National Weather Service Omaha/Valley NE
311 PM CDT SAT OCT 15 2016

.SHORT TERM...(tonight through Tuesday)
Issued at 306 PM CDT Sat Oct 15 2016

The extent of low clouds and potential fog/drizzle, and the effect
on temperatures the next few days, is the primary forecast concern.

Mid level trough extending from Manitoba into the Central Plains had
pushed a weak cold front into northeast Nebraska this morning, where
dew points had dropped into the 40s. Ahead of the front, dew points
were in the 60s across the rest of eastern Nebraska and southwest
Iowa. And extensive cloud cover was noted over the southeast half of
our CWA. Front is expected to drift only a little farther southeast
into this evening before working back north or washing out as weak
southerly low level flow is induced by lowering pressures in the
Northern High Plains ahead of approaching mid level trough. That
trough is forecast to spin off one piece of energy across the
Northern Plains Sunday which pushes a weak front into our area
Sunday night. But just like this morning, that front will quickly
lift back north or wash out as pressures lower to the north with the
approach of a stronger front expected to arrive Monday evening.

The main impact of each of these frontal boundaries will be on cloud
cover and thus temperatures through Tuesday as atmospheric moisture
is scant save for the boundary layer. With weak flow gradually
becoming southerly tonight, expect low clouds to once again spread
north to cover most of eastern Nebraska and western Iowa. And with
fog already evident in southwest Iowa, and most hi-res short-range
model output suggesting dense fog formation, will issue a dense
fog advisory for southwest Iowa. The fog could be more widespread
into eastern Nebraska, and will watch trends for possible
expansion of that advisory. Forecast soundings and persistent
southerly flow both suggest clouds will be slow to clear if at all
during the day Sunday. The effect on temperatures will be higher
lows and lower highs later tonight and Sunday afternoon.

The front Sunday night will only briefly slide into northeast
Nebraska before lifting back north, so no real impact is expected.
However as the third boundary approaches later Monday, low level
flow should become southwesterly and will promote eroding of clouds
during the day. Thus again rather mild lows are forecast Monday
morning with warmer afternoon temperatures given sunshine and
warming downslope westerly wind component. Highs in the 70s Sunday
should rebound into the 80s for most spots Monday afternoon.

850 temperatures ahead of Monday night cold front will average 20-
25C, dropping to 7-10C Tuesday afternoon behind front. However low
clouds should be scoured out by then, so despite the significant
cooling, expect highs to still rebound into the upper 60s and
lower 70s Tuesday afternoon.

.LONG TERM...(Tuesday night through Saturday)
Issued at 306 PM CDT Sat Oct 15 2016

Cooler temperatures will be the main weather story for the rest of
the work week as upper trough slides into and through the Plains
during the period. There is a chance for rain with the trough
passage, but much of the week should remain dry.

Models are in general agreement with trough axis moving through
eastern Nebraska and western Iowa by Thursday afternoon. Ahead of
it, warm advection in broad diffluent flow regime will cause area of
rain showers across Nebraska beginning Tuesday night and sweeping
across eastern Nebraska on Wednesday. A gradual southeast shift to
this area should keep rain chances in southeast Nebraska and
southwest Iowa into Thursday morning. But beyond that, can`t see
much chance for precipitation in northwest flow regime behind

Otherwise temperatures should average the 50s and 60s for highs
Wednesday through Saturday as 850 temperatures remain in the single
digits through the week. The coolest day appears to be Friday when
thermal trough settles into the Mid Missouri River Valley region.
Freezing temperatures could occur Friday morning with highs in the
low to mid 50s in the afternoon.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1224 PM CDT Sat Oct 15 2016

Latest sfc obs this aftn showing MVFR conditions pretty much
encompassing ern Neb. However...vsbl satl imagery was revealing a
few breaks from the llvl cigs over the region. And at this
point...trends indicate KOFK and KLNK should be going VFR within
the next couple hours. Expect deteriorating conditions though to
return late this evening with both terminals falling into the
MVFR/IFR range through most of tonight. As for KOMA...model
guidance is suggesting NIL improvement with MVFR/IFR conditions
pretty much prevailing through the fcst pd.


.OAX Watches/Warnings/Advisories...
IA...Dense Fog Advisory from 2 AM to 9 AM CDT Sunday for IAZ055-056-



LONG TERM...Dergan
AVIATION...DEE is the U.S. government's official web portal to all federal, state and local government web resources and services.