Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 171738
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1138 AM CST Fri Nov 17 2017

.SHORT TERM...(Today through Sunday)
Issued at 315 AM CST Fri Nov 17 2017

Fairly complex forecast with temperatures today and precipitation
tonight the main concerns.

Modest west/southwest mid level flow was in place from the
nations mid section back to the western United States. Main area
of height falls at 00Z extended from southern Saskatchewan down
into MT then back toward ID and OR. There were a couple of jet
segments noted in the 300 mb flow, one over MT and another over
central CA. At 850 mb, a thermal ridge extended from Mexico up
into CO, WY and then to along the MT/ND border. Decent moisture
at 850 mb (dewpoints 2 degrees C or higher) was lifting north from
TX, OK and parts of KS. That moisture had moved up into parts of
southeast NE and southwest IA based on recent RAP model
initializations and recent observations.

Today, just how warm it will get as warm is a challenge since
there is not a clear signal as to how deep we will mix. Forecast
will have highs mainly in the 50s north and in the 60s for about
the southern 1/2 to 1/3 of the forecast area. Some light rain or
drizzle is expected, mainly this morning, when low level cloud
thickness will be deepest. Winds should shift to the north or
northwest across all of the area by mid to late afternoon with the
low levels drying temporarily.

Short range models are in fairly good agreement that forcing for
ascent will be stronger tonight. Lift will be mostly at and above
700 mb, and this will shift southeast through the area with time.
The airmass becomes cold enough for a light rain/light snow mix in
parts of northeast NE late tonight, but it appears that the
precipitation will be ending about the time or shortly after the
changeover occurs. For that reason, expect little or no snow
accumulation. Some light rain could linger in parts of southeast
NE and southwest IA into mid morning Saturday, until the mid level
trough moves east of the area, then the rest of the weekend
should be dry.

.LONG TERM...(Sunday night through Thursday)
Issued at 315 AM CST Fri Nov 17 2017

Fast westerly flow aloft should become northwest by Monday night
then turn to the north by mid week as a 500 mb ridge amplifies
from northern Baja toward Saskatchewan and Manitoba. Model
agreement falls off later in the week, but it does look like the
pattern should be dry. Highs will be mostly in the 50s Monday, in
the 40s Tuesday and Wednesday, then back to the lower and mid 50s
for Thursday into Friday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1136 AM CST Fri Nov 17 2017

Lingering MVFR ceilings may lift for a few hours this afternoon
but will deteriorate again this evening if they do. Winds will
shift to northwesterly and increase to around 10-15kt through the
afternoon/evening. Behind that cold front, rain could affect all
sites tonight. Later tonight, there is some potential for rain to
mix with snow. For now, have included this mention as tempo only
at KOFK, but the potential at KOMA/KLNK bears watching.

&&

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

$$

SHORT TERM...Miller
LONG TERM...Miller
AVIATION...Mayes



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