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000
FXUS63 KGID 160624
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
124 AM CDT Mon Sep 16 2019

...Aviation Update...

.SHORT TERM...(This evening through Monday Night)
Issued at 254 PM CDT Sun Sep 15 2019

Warm again on Monday...

The axis of an upper ridge across the interior CONUS was
migrating eastward today ahead of an upper trough moving into the
Pacific Northwest...with a lead shortwave trough lifting out of
the south central Rockies. This lead system will bring an increase
in cloud cover during the day Monday, but otherwise expect
continued warm temps for mid September with highs well into the
80s to lower 90s. Winds will be noticeably stronger from the
south with gusts of 25-30 mph in a tightening pressure gradient.

Monday night...a new trend in latest models is the potential for
isolated convection in a warm air advection regime with lift
enhanced by a strengthening low level jet. Have included slight
chances for storms from late evening through the overnight hours.
Winds look to remain steady/gusty through the night which well
help hold up low temperatures around the 70 degree mark. These
temperatures are close to current records for warm minimum lows.
The current record warm minimum for September 17th for Hastings is
72 degrees..with a forecast of 71 degrees. Grand Island`s record
of 75 degrees should be safe...with a forecast low of 71 degrees.

.LONG TERM...(Tuesday through Sunday)
Issued at 254 PM CDT Sun Sep 15 2019

A more active pattern is setting up across the region during the
extended period. The new pattern will cycle a few disturbances
through the plains...creating several opportunities for scattered
thunderstorm chances, as well as some breezy and gusty days...and
possibly more fall like weather on Sunday.

An upper level trough is expected to be coming across the
intermountain west on Tuesday and will result in a tightening
surface pressure gradient across the plains...thus giving us a
rather breezy and possibly gusty day on Tuesday. MET guidance
currently has sustained winds in the 20-25 mph range, with higher
gusts expected due to winds aloft at 850 mb in excess of 40 mph. As
the trough then crosses the northern plains, the associated cold
front brings chances for some scattered thunderstorms overnight
Tuesday and even into Wednesday and Wednesday night.

Thursday looks to be the relatively "calm" day as we transition
between systems. Then on Friday, as the next upper level disturbance
approaches from the west, we can expect to see somewhat of a repeat
of Tuesday...a much tighter pressure gradient ahead of the trough,
bringing breezy and gusty winds. However, this time around, models
show the trough to be deepening much more as it approaches the
plains. As it currently stands, this stronger system will bring even
better chances for showers/thunderstorms heading into the weekend,
and more fall like temperatures for Sunday behind a cold front.

&&

.AVIATION...(For the 06Z KGRI/KEAR TAFS through 06Z Tuesday)
Issued at 124 AM CDT Mon Sep 16 2019

General overview:
By far the main issue involves winds, both breezy at the surface
and stronger aloft, resulting in two distinct periods of low
level wind shear (LLWS). See below for more on this.

Confidence is actually very high in VFR ceiling/visibility through
the period, with only considerable passing high level (and
limited mid level) cloud cover. Confidence is also high in a
dry/precipitation-free forecast, although there is a tiny chance
that a few rogue sprinkles/showers could perhaps be in the general
area Monday night (certainly not worthy of a formal mention).

Getting back to the main issue of winds. Surface winds will
prevail southerly throughout the period. Sustained speeds early
this morning will average under 10KT, but a noticeable increase
will occur into the daylight hours, with especially the 16-00Z
time frame featuring sustained speeds 15-20KT/frequent gusts
around 25KT. Turning to LLWS, have two distinct periods
advertised. The first is right away this morning through around
14Z, as winds within the lowest 1,000 ft. will average around 40KT
from the south-southwest, resulting in 30-35KT of shear
magnitude. The second one ramps up late in the period 03-06Z, as
winds within the lowest 1,500 ft. will accelerate to around 45KT
from the south, also resulting in generally 30-35KT of overall
shear.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&

$$

SHORT TERM...Fay
LONG TERM...Shawkey
AVIATION...Pfannkuch