Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 280934
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
434 AM CDT Wed Jun 28 2017

.SHORT TERM...(Today and tonight)
Issued at 428 AM CDT Wed Jun 28 2017

Last night`s rain and thunderstorms have mostly exited the area,
with only a few showers and weak thunderstorms remaining across
northern KS. A weak surface front will gradually slide
southeastward across the area this morning, before stalling in
the southeastern portion of the CWA this afternoon. This may
provide a focus for a few isolated thunderstorms late this
afternoon and evening. That said, convective-allowing models keep
the majority of this activity farther east across southeastern NE
and IA. Therefore, I only included a slight chance of thunder
southeast of a line from Osborne, KS to Geneva, NE during this
timeframe. If storms develop in this area, temperatures in the low
90s will provide plentiful instability. Bulk shear of 30 to 40
kts would also support an isolated strong to severe storm.

The main story for the short term period comes tonight. There are
some model differences, but the general idea is that scattered
thunderstorms will develop in the late evening and overnight in the
presence of increasing southerly flow at the surface and at 850mb
and another low-amplitude shortwave passing through the Great
Plains. This will once again evolve into one or more convective
complexes as convergence at 850mb increases. This is where models
differ a bit. The GFS shows the best convergence along the KS/NE
state line, but the NAM is along I-80. Right now, I tend to favor
the former solution, and as a result, I think that the heaviest rain
will occur over the southern half of the CWA.

Large hail is possible, especially early on in the event with
around 3000 j/kg of CAPE to work with. Later into the overnight,
it may become move of a wind and heavy rain threat as as storms
build into the low-level jet. If the heaviest rain band ends up
being farther north, the flash flooding threat would be a bit
higher, as these areas received 1-2" last night.

.LONG TERM...(Thursday through Tuesday)
Issued at 428 AM CDT Wed Jun 28 2017

Overview...There will continue to be at least a few more chances for
thunderstorms with appreciable moisture. The best chances for more
widespread thunderstorms during this forecast period will be
Thursday afternoon/evening and then again Sunday into Sunday night.
Otherwise, most areas should be dry Friday into Saturday and Monday
into Tuesday July 4th.

We do expect a cool down after finally getting back to around 90
today, most Nebraska zones will only see highs in the lower 80s
Friday and Saturday and then mid 80s for Sunday into July 4th.
Kansas zones will be just a few degrees warmer. Normal highs are now
generally in the mid to upper 80s over south central Nebraska to
around 90 over north central Kansas.

Thursday...Confidence in precipitation chances is still rather low
with a variety of differing forecast model solutions out there. The
06Z NAM and several 00Z WRF models have a few remaining Wednesday
night thunderstorms quickly exiting to our east Thursday morning and
then are dry until thunderstorms that form along the cold front over
the high plains move in from the west during the evening hours. The
00Z ECMWF is faster and would have perhaps some early evening
thunderstorms across our east and then everything is pretty much
east and southeast of our forecast area after 7 pm. The 00Z GFS has
thunderstorms developing by early afternoon favoring our east and
then has most of the thunderstorms east of our forecast area after
dusk.

All models considered, believe there will certainly be some severe
thunderstorms around the area primarily late Thursday afternoon and
evening with perhaps the eastern zones having the little better
chance. The SPC severe weather outlook for Thursday is calling for
an enhanced risk for severe weather, which certainly seems
reasonable given the 3000 J/kg MLCAPE values and 0-6 km shear values
generally around or at times over 40 kts. Severe thunderstorm
clusters may eventually merge into a MCS with heavy rain possible
during the evening/overnight hours.

Friday through Saturday...Should be dry and the coolest days of the
period with highs only in the lower 80s Nebraska to mid 80s over
Kansas.

Saturday night through Monday...We will generally be in a northwest
upper flow pattern although a stronger trough within the overall
northwest flow pattern will flatten the upper flow out on Sunday to
at least briefly a more zonal pattern and bring us one of our
potentially better chances for thunderstorms Sunday into Sunday
night. Otherwise, thunderstorm chances will be lower and more
isolated Saturday and Monday. Instability and wind shear currently
look rather impressive for Sunday and thus will need to keep an eye
out for severe thunderstorms this day.

Tuesday 4th of July...It is currently looking dry with near normal
temperatures in the mid 80s Nebraska to around 90 over north central
Kansas.

&&

.AVIATION...(For the 06Z KGRI/KEAR TAFS through 06Z Thursday)
Issued at 1241 AM CDT Wed Jun 28 2017

Scattered showers and thunderstorms will continue to move across
the area. This will keep winds variable over the next few hours. There
have been a few stronger wind gusts as these showers mix down
winds from the low-level jet. Based on radar trends, activity
should move east of the terminals by around 9Z. This seems to
match the HRRR relatively well.

Winds will weaken and shift to the northwest by morning as a
surface trough/front moves through.

Thunderstorm redevelopment should remain just southeast of the
terminals tomorrow afternoon, but there is potential for another
complex of thunderstorms late tomorrow evening and overnight.

&&

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

$$

SHORT TERM...Mangels
LONG TERM...Wesely
AVIATION...Mangels


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