Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 221959

Area Forecast Discussion
National Weather Service Hastings NE
259 PM CDT SUN MAY 22 2016

...This Week Could Be Very Busy with Multiple Episodes of Severe
Tstms with Flooding Possible in Areas where Storms Repeatedly
Dump Heavy Rainfall...

.SHORT TERM...(This evening through Monday)
Issued at 259 PM CDT Sun May 22 2016

Aloft: Moderately amplified flow was over the CONUS. Today began
with a ridge over the Plains...but it has departed to the E. A
large trof was over the Wrn USA and a shortwave trof was lifting
out of its base and was over UT. This trof will cont NE
tonight...crossing CO/WY into the Dakotas by daybreak Mon. The
mean Wrn trof will retrograde a bit...but low amplitude SW flow
will remain over the Plains.

Surface: A Pac cool front extended from the Wrn Dakotas thru the
Neb Panhandle then SW thru CO/UT/NV. A dryline intersected the
front over Ern CO. The cool front will cont E across the Nrn
Plains tonight with its more Srn portion moving slower to the E.
Present indications are that the front will enter the fcst area
around dawn Mon. It is expected to stall over the fcst area...with
alterations possible due to tstm outflows.

Now: lots of cloud cover remains over the fcst area and despite
this...temps have managed to climb well into the 70s and low 80s.
Dwpts are the highest they`ve been so far this warm
the low-mid 60s.

Am not expecting much additional tstm activity to affect the fcst
area this afternoon. Isolated tstms will develop over Wrn Neb and
KS close to the dryline/cool front. Can`t rule out one or two of
these storms affecting areas W of hwy 183.

Please see MD #677. A watch appears likely just W of the fcst area
and probably against our Wrn border.

Tstm coverage will be more significant well N and W of the fcst
area this afternoon/eve...closer to the vort max. This activity
should grow upscale into one or more MCSs from SD into the Neb
Sandhills this eve. One of these MCSs could move in after
midnight. Strength/ severity is uncertain. Time of day argues
against severe and it should be weakening/cold pool-dominant...but
it can`t be ruled out with MUCAPE 1500-2000 J/kg.

Mon: Tstms may be over/exiting part of the fcst area during the
morning. What happens thereafter is highly uncertain. We could be
socked in with stratus in the wake of the storms.

WV imagery shows a subtle shortwave trof approaching Baja CA.
This trof will be ejecting across the Cntrl/Srn Plains during peak
heating. With the presence of the cool front/dryline and possibly
outflow boundaries...expect sct tstms to erupt mainly E and S of
the fcst area. But a few could occur S and E of the Tri-Cities
"if" morning clouds clear out and heating occurs.

Trying to determine the environment is tough given that cloud
coverage and temps are unknown in the wake of whatever occurs in
the morning.

.LONG TERM...(Monday night through Sunday)
Issued at 259 PM CDT Sun May 22 2016

Fcst uncertainty is above normal. Tstm potential hinges on small-
scale but important features that have low predictability. This
includes the tstms themselves as they can and will determine where
future tstm potential exists. Remnant cloud cover in the wake of
tstms also complicates temp fcsts as well as environmental

Aloft: SW flow will remain over the Plains as the longwave trof
remains locked over the Wrn USA. Subtle/low amplitude embedded
shortwave trofs will provide dynamic forcing...enhancing tstm
potential from time to time. As of now...the most identifiable trof
is fcst to eject out of the Wrn trof on Fri.

Surface: The weak front that stalls from SW-NE across the Cntrl
Plains into the Great Lakes will become wavy and modulated by
multiple rounds of MCS activity. Little else will change.

Really can`t add much in the way of details because the fcst so
heavily hinges on mesoscale features that largely have yet to be
determined. All we can say at this point is there is a risk of
tstms every day. Some days will produce more than others.

Certainly the environment will be favorable for svr tstms. The
supply of Gulf moisture will be uninterrupted and deep layer shear
will be favorable for organized tstms and tstm clusters. All forms
of svr wx will be possible.

This week should be warmer than last week.

Flooding: this could be a very wet week in parts of the fcst area.
Some isolated spots could see svrl inches of rain.


.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Monday)
Issued at 1231 PM CDT Sun May 22 2016

Significant Weather: Periods of MVFR/IFR Cigs. LLWS tonight.
Potential for IFR tstms 08Z-13Z Mon.

NOTE: confidence in cloud coverage and CIG height is low due to
poor model consensus and lack of proper representation of present

This afternoon: MVFR CIGs may occasionally become SCT and/or lift
to around 4K ft. S winds around 20 kts with G25-30 kts.
Confidence: Medium

Tonight: MVFR CIGs may cont or there may be a period of VFR CIGs.
LLWS develops by 03Z. MVFR CIGs probably overtake the terminals
once again...and may lower to IFR after 06Z. A period of IFR tstms
possible after 08Z. S winds occasionally G25 kts. Confidence: low

Mon: IFR Tstms may be on-going or nearby but exit to the E early.
Probably IFR CIGs which will gradually lift to MVFR by 16Z. S
winds 10-15 kts. Confidence: low


.GID Watches/Warnings/Advisories...


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