Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 211754

Area Forecast Discussion
National Weather Service Hastings NE
1254 PM CDT Fri Sep 21 2018

.SHORT TERM...(Today and tonight)
Issued at 346 AM CDT Fri Sep 21 2018

Today...Cold air advection will occur behind the departing mean
shortwave trough that helped spawn convection yesterday. A surface
ridge with a near 1027 mb surface high moves across the central
Plains today. Although sunny conditions are expected from strong
subsidence behind the upper trough, the cold air advection will
be strong enough to limit highs to the mid 60s to around 70, about
10 degrees below average for the tri- city area.

Tonight...We will wind up on the back side of the surface ridge
with light return flow by morning, but still light enough for
quite a bit of radiational cooling, with lows in the 40s as the
surface mass remains cool with little modification.

.LONG TERM...(Saturday through Thursday)
Issued at 346 AM CDT Fri Sep 21 2018

Saturday...Southwest flow aloft develops as another shortwave trough
quickly digs into the Great Basin region. Also, some warm air
advection occurs on the backside of the surface ridge and ahead of
a deepening lee side surface trough. This will help boost highs
to the lower to mid 70s, especially with dry dewpoints around 50
degrees in the afternoon. This is still a bit below normal high
temps, but still warmer than what is anticipated for today. Used
CONSMOS wind for Saturday with the expected warm air advection.

Sunday...Increased warm air advection will increase temperatures
even more than Saturday ahead of a cold front approaching from the
northwest and a lee trough to the west. Highs should be near 80.

Monday...The combination of the deepening lee trough and pre-
frontal warm air advection, and mixing directly behind the cold
front, in the mid 70s to near 80. Convection could fire by late
afternoon near and ahead of the cold front as it moves through.

Monday evening...This will be about our best shot at some rain
potential. Along and ahead of the cold front associated with a
shortwave trough, I expect convection to develop. By the time
most precip has a chance to develop, it will more likely be
focused in central to southeastern parts of the County Warning
Area (CWA). We may have enough instability and shear for some
severe weather late afternoon to evening on Monday, especially in
our southeast, so stay tuned to future forecasts if solutions
steer more consistently toward this.

Temperatures will generally be 5 to 10 degrees below normal for
the rest of the forecast after Monday as a significant upper
trough swings through the northern and central Plains. After
Monday, expect highs in the 60s to lower 70s and lows around 50.
There will still be some small chances of precip hanging around
for Tuesday as the short to mid-wave trough axis will not pass
east until at least Tuesday afternoon with perhaps just enough
residual moisture, and will help reinforce the larger mean trough
for much of the rest of the work week as the trough, helping to
keep temps on the cool side. Small chances of precip are possible
for parts of the rest of the forecast in the long term with low-
amplitude perturbations, but moisture will be limited, and
instability will be lacking.


.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Saturday)
Issued at 1233 PM CDT Fri Sep 21 2018

VFR conditions are expected through the period as clear skies and
good visibilities are expected to prevail across the local area.
Expect breezy northwesterly winds behind yesterdays front to
slowly diminish during the late afternoon hours...with high
pressure settling into the Missouri river valley overnight helping
to shift the winds to a more southerly direction by Saturday




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