Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 101717

Area Forecast Discussion
National Weather Service Hastings NE
1217 PM CDT Thu Aug 10 2017

Issued at 942 AM CDT Thu Aug 10 2017

The dense fog advisory has now been cancelled across our cwa this
morning as visibilities have risen above dense fog criteria.


.SHORT TERM...(Today and tonight)
Issued at 449 AM CDT Thu Aug 10 2017

Quiet conditions remain in place across the CWA early this morning,
with upper level data showing continued low amplitude northwesterly
flow, set up between high pressure over AZ/TX/Mex border area and
low pressure spinning over eastern MN. At the surface,
light/variable-calm winds are in place across the entire CWA. The
pattern remains weak early this morning, sitting just south of a
frontal boundary associated with low pressure over MN. Main concern
this morning will be with fog, thanks to a lack of overall cloud
cover and light winds. Decided to go with a Dense Fog Adv for the
majority of the area this morning. A number of sites are at/have
been flirting with 1/4 mi for a while now, and the RAP/HRRR/NAM
visibilities are not showing any improvement. No big surprises with
temps, with 3 am obs in the upper 50s and lower 60s.

Once the morning fog dissipates, the main concern through the short
term period turns to thunderstorm chances. Models showing a mid-
upper level shortwave disturbance sliding east-southeast out of the
Rockies through the day, but have some minor timing differences with
precip across the area. Kept the 12-15Z period dry, with PoPs moving
in after 15Z, but some of the latest runs suggest that it may be
closer to midday before activity really starts moving into the CWA.
Currently have the better chances coming after 18Z, and gradually
pushing south as the wave continues to move east through the
Plains. There will be the potential for some storms to be
strong/severe this afternoon and evening, mainly for areas
near/south of the NE/KS state line, with models showing modest
instability developing and sufficient deeper layer shear. Had
inherited a HWO mention of ping pong balls/60 MPH winds, kept that
going. There is some uncertainty with how quickly activity will
slide south of the CWA. Most of the models have show much of/if
not all activity moving south by mid evening, 06Z run of the NAM
lingers chances well after midnight. Have PoPs tapering down to
only slights after 06Z, and dried the area out for 09-12Z.

High temperatures today are forecast to reach the mid 70s to
lower/mid 80s. Precip moving in during the afternoon may have more
of an impact on highs, so confidence highs main for the central and
northern portions of the CWA is on the low side. Overnight lows
tonight are forecast to drop into the 50s for most, near 60s across
the south.

.LONG TERM...(Friday daytime through Wednesday)
Issued at 449 AM CDT Thu Aug 10 2017

General overview of this 6-day period:
This forecaster apologizes for those tiring of reading the largely
"broken-record-sounding" assessment of the Day 2-7 situation the
past several nights, but once again there just aren`t a lot of new
things to discuss, although at least there are hints of a minor
pattern change/possible warming trend on the horizon for next
week. For the most part though, and especially through the weekend
into early next week, the story remains remarkably similar.
Temperature-wise, we continue to have high confidence that we will
end up with basically 3 FULL WEEKS of below average/normal
conditions lasting through at least Wednesday. On the other hand,
and as is typical in this type of summer weather pattern,
confidence in our plethora of rainfall chances (PoPs) and
thunderstorm intensity/severity is lower, especially beyond
Saturday. In the nearer term though, confidence is growing that at
least one forecast period (Friday daytime) may be approaching
"guaranteed dry" status for most/all of the local area.

Basic mid-upper level weather pattern/rain chances:
From Friday-Sunday, the overall pattern remains largely unchanged
from the current situation, as the Central Plains generally
remains under west-northwest flow aloft along the interface
between ridging centered over the southern CONUS and broad
troughing across southeast Canada extending into the northeast
CONUS. As such, a parade of disturbances will continue brushing
over/near our local area, with the primary/strongest one centered
during the Saturday-Sat night time frame. Not surprisingly, the
Friday night-Saturday night periods feature our highest PoPs of
generally up to around 50 percent. By Days 4-7 (Mon-Wed), at least
a minor pattern change will get underway, as both the ECMWF/GFS
agree that we will see a transition to a more true quasi-zonal
(west-east) flow pattern. Generally speaking, this would mean at
least a slightly warmer temperature regime and probably a bit
drier weather pattern (at least compared to this weekend), but the
forecast still remains "littered" with a number of fairly small
PoPs, with the latest raw model data suggesting our strongest
passing mid level wave/best rain chance of rain for the first half
of next week MAY arrive around Tuesday-Tues night, but this is
still plenty subject to uncertainty.

Very little change in day-to-day highs/lows versus the previous
forecast package. This means that highs in most of the coverage
area (CWA) on most days should top out somewhere between the upper
70s and low 80s, although a greater concentration of mid 80s will
probably start showing up especially in southern areas toward the
middle of next week. Although technically just beyond our current
official 7-day forecast, there are preliminary indications that
next Thursday MIGHT have the potential to be the overall-warmest
day the CWA as a whole has seen in basically 3 weeks, with more
prevalent mid-upper 80s and perhaps even a few 90s...time will
tell. Overnight lows through most of the long term will average in
the low-mid 60s, with more in the way of mid 60s likely by days
6-7 as the "minor" warm-up commences.

Thunderstorm intensity/severity and rainfall potential:
Right away for Day 2 (Fri-Fri night into Sat AM), we appear to get
at least a one-day respite from severe thunderstorm chances,
thanks to a good chance of a dry day and only meager instability
with any storms that might move in from the west in the late
evening/overnight. However, as early as Saturday afternoon-night,
at least a small risk for severe storms is right back in the
picture, especially for our western counties where the highest
instability values perhaps up around 1000 J/kg could reside.
Interestingly, the last few NAM runs suggest that a potentially
organized storm cluster/mesoscale convective system could dive
into our area from the northwest Saturday night, but this is just
far enough out that it`s difficult to take it to the bank. For
now, SPC only clips our extreme west with an official Marginal
Risk on the current Day 3 outlook for Saturday afternoon-night,
but would not be surprised to see this expanded at least slightly
east on future Day 2/1 issuances. Beyond Saturday night, trying to
assess any kind of "specific" severe potential gets murky, but the
overall weather pattern at least supports limited/spotty severe
potential from time to time, and would anticipate that another
Marginal Risk or two could ultimately materialize especially
sometime in the Day 4-7 range. As for rainfall potential, again
saying the same thing as previous nights here, but the WPC total
7-day QPF progs are still calling for a widespread 1-2" across
nearly the entire CWA through the middle of next week, although
much of this precipitation potential will probably occur over the

Fog potential:
Although we probably cannot rule out some patchy fog Thursday
night/early Friday morning, current models/guidance do not look
nearly as favorable for dense/impactful fog as this morning`s
situation, so have elected to hold off on a formal forecast
mention for now and give next few shifts another look. Thereafter,
there are actually no truly "obvious" signals for dense fog issues
at least through Friday night and Saturday night. Still something
to keep an eye on though in later forecasts.

Again tonight, will finish with a few comments regarding the
closest-range "long term" periods, in this case Friday-Friday

Friday-Friday night:
Technically, Friday daytime is the ONLY one of the 11 long term
day/night forecast periods to currently feature a dry forecast
CWA-wide, as we largely remain "in between" passing upper level
disturbances, and under the influence of transient surface high
pressure. Along these same lines, this also looks to be our
overall-sunniest day of the next several days, so sun-lovers will
want to take advantage of this. Breezes generally only 5-10 MPH
and somewhat variable in direction. This will probably be one of
the overall-warmer days we have seen in awhile, with most of the
CWA aimed into the 81-83 range (albeit still slightly below
normal). Friday night, have some small shower/non-severe storm
chances creeping into western zones pre-midnight, but somewhat
better chances should hold off until the late-night hours/closer
to sunrise Saturday, again mainly favoring our western zones per
the GFS/ECWMF. However, it`s worth noting that the latest NAM is
eerily dry late Friday night so there is some uncertainty here. No
matter, am not expecting any severe storm threat through these 24


.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Friday)
Issued at 1213 PM CDT Thu Aug 10 2017

Showers and a few thunderstorms will continue to spread east this
afternoon and early evening, crossing the terminals with the
stronger storms expected south of the terminals. Chances for
precipitation continue into the first part of the night before an
upper level disturbance moves east. Cannot completely rule out the
potential for fog development overnight, but have not included in
TAFs just yet and this will need to be monitored.


Issued at 449 AM CDT Thu Aug 10 2017

..Both Grand Island/Hastings still in the running to POTENTIALLY
threaten records for "Consecutive July-August days without exceeding
85 degrees"..

For those interested in unique consecutive-days streaks, both Grand
Island and Hastings are in the midst of a fairly impressive streak
that could threaten current records: "Consecutive July-August days
without exceeding 85 degrees". Because both July-Aug are solidly the
warmest two months of the calendar year on average, any prolonged
streak without exceeding 85 is a pretty "big deal", especially
considering that normal/average highs through both months range
mainly 84-88 degrees.

As of this writing, both Grand Island and Hastings are up to 15 DAYS
without exceeding 85, a stretch that began on July 26th. However, to
set/tie records, this streak will have to last another 6-8 days,
which DOES appear to be a possibility. Details of the current
records follow:

* Top-4 Longest July-August streaks without exceeding 85 degrees *

- Grand Island (records include 121 years):
21 days...Aug. 11-31, 1964
18 days...July 11-28, 1993
16 days...July 8-23, 1992
15 days...July 26-Aug. 9, 2017 (ONGOING) and Aug. 17-31, 1944

- Hastings (records include 111 years):
22 days...Aug. 5-26, 2008
21 days...Aug. 11-31, 1964
16 days...July 16-31, 2000 and Aug. 13-28, 1927
15 days...July 26-Aug. 9, 2017 (ONGOING)...July 20-Aug. 3, 1996
          and Aug. 10-24, 1951




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