194 
FXUS63 KGID 042208
AFDGID

AREA FORECAST DISCUSSION
National Weather Service Hastings NE
508 PM CDT Sun Apr 4 2021

.UPDATE...
Issued at 505 PM CDT Sun Apr 4 2021

...MESOSCALE UPDATE...
Recent GOES 1 min data along with regional radar data shows
iso convection developing over far W portions of the CWA within
the past hr. Sfc obs suggest this activity may be developing along
subtle moisture gradient from between LBF and LXN, southwestward
to between KOEL and KHLC. This activity is developing in a very
hot, well mixed environment that has likely led to local errosion
of CINH. Latest SPC objective analysis shows about 500 J/kg of
MLCAPE, but only weak effective shear (less than 25 kt).
Furthermore, DCAPE is analyzed to be 1400 J/kg, which is rather
significant, and MLLCLs are likely in excess of 3km. This seems
more than reasonable given sfc T/Td spreads of 40-50F or more.
All of this suggests an isolated strong wind gust potential can't
be ruled out with the strongest cells. Forcing appears weak and 
largely diurnally driven, thus, feel like the overall threat will:
1) remain isolated and largely non-severe 2) remain mainly W of
Hwy 183 and 3) be mainly between now and sunset. Have added this
information to the HWO, and plan to handle iso wind threat with
SPSs.

...FIRE WEATHER...
Ongoing RFW appears mostly on track. Air temps have overachieved
into the upper 80s to low 90s, and Tds are only upper 30s to low
40s. Wind gusts are generally around 30mph for areas near and
close to the RFW. Locations that remain out ahead of expanding 
cld cover will have the greatest concern thru about 00Z to 01Z. A
wildfire was detected along Smith/Osborne County line around 21Z,
and fire spread was noted to be rather rapid.

&&

.DISCUSSION...(This evening through Sunday)
Issued at 320 PM CDT Sun Apr 4 2021

A slow moving and weak line of CU is tracking towards the western
fringes of the local area this afternoon. While there is around
1000 J/KG of surface based cape to work with...shear is fairly
minimal and forcing is weak...so strong to severe thunderstorms
are not expected. That said...expect this CU to continue to slowly
expand in coverage and for a few showers and thunderstorms to be
realized locally as the line tracks east...eventually being 
enhanced by the nose of a weak low level jet feeding into the 
line later this evening. Overall...while there will be some 
showers and thunderstorms around...will continue to downplay the 
threat for any severe weather tonight. 

As this line moves easy by morning...expect another well above
normal day...temperature wise...as 850 mb temps remain largely
unchanged. In fact...may not have gone quite warm enough for 
tomorrow as a fairly strong front will be dropping down from the 
north...and could see some adiabatic compression help enhance 
afternoon temps ahead of this front tomorrow afternoon. As this 
cold front reaches the local area tomorrow night...have a better 
chance for more widespread precipitation in the forecast as this 
front should act as a focal point of thunderstorm development. 
Given the increase surface dewpoints tomorrow...corresponding 
higher CAPE values and better shear...could even see a few 
isolated strong to marginally severe storm with the initial front
as it cross the local area. 

That said...the better chance for severe weather will likely come
on Tuesday...when an upper level low tracks south across Kansas 
during the daytime hours. Not surprisingly...much of the local 
area is highlighted in a marginal risk for severe weather 
Tuesday...and would not be surprised to see this risk expanded 
further north as forcing along the secondary cold front should 
provide some shear and help tap instability during the afternoon 
hours. Thunderstorm activity should then transition to more 
showery/rain activity overnight...as instability will wane behind 
the cold front and forcing from the nocturnal LLJ should be 
focused to our south and east. 

As clouds linger and strong north winds are forecast for
Wednesday...expect a noticably cooler and unpleasant day across
the local area as temperatures drop below normal and the strong
northerly winds will make it feel even cooler. Modest discrepancy
then exists with the following upper level trough late in the
week...but currently the official forecast remains dry...with
slightly above normal temps closer to 70 returning for the end of
the week and into next weekend.



&&

.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Monday)
Issued at 1136 AM CDT Sun Apr 4 2021

Winds are expected to become breezy this afternoon but will taper
off after sunset. VFR is forecast through the period. Looking at 
the models for this evening, some TSRA look possible around the 
area, but currently have low confidence of one impacting the TAF 
sites as activity looks isolated in nature. Only one model brings 
on station, so decided to keep VCTS out of the TAFs at this time.


&&

.FIRE WEATHER...
Issued at 320 PM CDT Sun Apr 4 2021

Gusty southerly winds were realized across much of the local area
south of Highway 6 this afternoon...and the combination of these 
gusty winds along with Relative humidity values dropping below 20
percent...in part due to overachieving temperatures...is 
resulting in critical fire weather conditions across parts of the 
area. Higher dew points to the south will eventually work their 
way north over the next few hours...but given dry conditions and 
one hot spot already popping up on satellite this afternoon...felt
a red flag warning was warranted. While temperatures will be 
similar Monday afternoon...notably higher dew points should help 
alleviate fire weather concerns tomorrow.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...Red Flag Warning until 8 PM CDT this evening for NEZ086-087.

KS...Red Flag Warning until 8 PM CDT this evening for KSZ005>007-
     017>019.

&&

$$

UPDATE...Thies
DISCUSSION...Rossi
AVIATION...Beda
FIRE WEATHER...Rossi