Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 280851
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
351 AM CDT Fri Apr 28 2017

.SHORT TERM...(Today through Sunday)
Issued at 351 AM CDT Fri Apr 28 2017

Very active forecast for the short term into the first part of the
extended. Early morning water vapor imagery indicated a potent
shortwave trough moving through the high Plains of western KS.
Strong 700-400 mb CDPVA was occurring over northern KS into
southern NEb and was responsible for an area of rainfall. Short
term models are in good agreement that this area of rain will
continue to lift to the north through eastern NEb and western IA
this morning. Over northeast NEb, around Boone and Antelope
counties, models indicate that as the atmosphere saturates we may
see some snow mix in for a few hours this morning. This appears
reasonable, but any accumulations would be very minor and just
confined to grassy surfaces. Otherwise just rain is expected with
this band of lift. We have lowered going highs today all areas
given the expected rain, clouds and low-level CAA through the day.
We will likely see the rainfall rates diminish through the early
afternoon as the best lift shift off to the north, but at least
into the evening we will likely see some sprinkles or a brief
shower.

The next shot of lift will start to head toward the area late
tonight and into the day on Saturday in the form of broad and
persistent isentropic upglide as heights aloft increase ahead of
an intense early spring jet carving out a large trough over the
desert southwest. This rainfall will likely spread north through
the day on Saturday as WAA in the 850-700 mb layer continues.
Longer range global models are in great agreement Saturday night
through Sunday night as the intense mid-level cyclone emerges onto
the southern high Plains, and then lifts northeast into Iowa by
Monday morning. The rainfall is likely to continue into Saturday
night ahead of this cyclone as mid-level deformation increases
leading to frontogenesis, and we start to get some influence from
the large-scale forcing. Sunday is shaping up to be a raw and
rainy day as intense lift moves through the region and
northeast/north winds increase. It appears through Saturday night
and most of the day on Sunday the precipitation across the entire
area will be rain.

.LONG TERM...(Sunday night through Thursday)
Issued at 351 AM CDT Fri Apr 28 2017

As the mid-level cyclone lifts through eastern KS and into
southern IA by Monday morning models indicate a well-developed
TROWAL over central NEb into eastern SD. Models indicate that
temperatures aloft will cool during Sunday night, and as surface
temperatures falling into the mid 30s we will likely see some of
the rain switching over to snow at this time. This is most likely
to the northwest of a line from Columbus to Norfolk to Wayne
where the combination of 800 mb 2-D frontogenesis, weak static
stability, and maximum DPVA will be juxtaposed allowing for this
cooling. Although ground temperatures are generally into the 40s
currently, given the rates expected and the event taking place at
night we should see some accumulation. We have included some 1-2"
amounts for the far northwest CWA at this time. As the system
pulls off to the east on Monday morning we will see precipitation
end as some light rain over this area as temperatures increase
into the mid and upper 30s.

Northwest flow is expected to develop after the system this
weekend with another shortwave trough brining a chance of showers
to the area on Tuesday/Wednesday with dry weather to end the
forecast period. Although we will see increasing sunshine through
the week temperatures will continue to average below normal for
early May.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday morning)
Issued at 1150 PM CDT Thu Apr 27 2017

VFR conditions initially, but becoming MVFR and eventually IFR
through the forecast. Showers becoming prevailing by 08z,
prevailing at KOMA by 10z and by 12z at KOFK. Rain may end from
south to north by 18-22z at KLNK/KOFK, but IFR conditions remain.
Light winds initially, becoming east northeast through time and
increasing to 13 to 23 knots. Could be a rain/snow mix at KOFK
14-17z.


&&

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

&&

$$

SHORT TERM...Boustead
LONG TERM...Boustead
AVIATION...DeWald



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