Forecast Discussion
NWS Omaha/Valley, NE

000
FXUS63 KOAX 201118
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
618 AM CDT Mon May 20 2019

.SHORT TERM...(Today through Wednesday)
Issued at 355 AM CDT Mon May 20 2019

Forecast concerns today will be how much of a limiting factor
will the easterly low level flow be. How much will the storms
across Kansas/Oklahoma inhibit the northward progress of the
heavy rain? Moderate risk of excessive rainfall area pulled
farther south and now a high risk area has been included...how
does this affect the flash flood watch headlines.

The forecast for Sunday worked out as expected with the clouds and
cooler temperatures in the 40s and 50s and skies clearing out
Lincoln southward and temperatures warming into the 60s there.
With the departing storm system, clouds lingered late Sunday night
with a few sprinkles.  Northwest winds persisted as surface high
pressure extended from the Dakotas into the forecast area and
temperatures were only in the 40s.

The closed area of h5 low pressure was location over CA/UT and is
responsible for broad synoptic lift across the southwest U.S. into
the Sierras/Rockies/Plains.  Water vapor satellite imagery
highlights the moisture streaming into the Plains. Convection is
erupting over parts of New Mexico and the Texas Panhandle, where a
severe thunderstorm watch is already in effect. The storms are in
a highly diffluent area with a 125-140kt jet, associated with
lead shortwave trough energy, where deep 10 to 12 h85 dewpoints
reside and 30 to 40kts low level southeast winds are feeding into
the storm system.

Through today, that shortwave trough energy lifts northeast across
Kansas, however the surface warm front remains well to the south.
Instability remains limited in our area and the dry flow from the
east will work to inhibit saturation. Some showers with the mid
and upper level forcing with lift across northeast nebraska and
eventually the rain will become more widespread across Kansas and
central Nebraska, working into eastern Nebraska. The focus for
the heavy rain will be across Kansas and Oklahoma where there is a
moderate to high risk for excessive rainfall. The high risk for
severe weather is from Texas into Oklahoma close to the
dryline/warm front.

Tonight...the closed h5 low is becoming negatively tilted over
CO/NM with moisture from the Pacific Ocean and the Gulf of
Mexico. PWAT values increase to 1.5 to 2 inches across Kansas.
There is concern that the storms over OK/KS will limit the
northward progress of the heavy rain. Later tonight into Tuesday,
the flow becomes more favorable for the northward transport of
higher PWATs of 1.5 inches into the OAX cwa, with the fetch of
deep moisture increasing rainfall rates.

The HiRes models really focus the heavy rain south across Kansas
/Oklahoma-HRW WRF-ARW, HRM-NMMB, RAP/HRRR...however the global
models to varying degrees bring some of the heavier rain farther
north. The GEFS plumes around 1.75" for OMA. Agree that rain will
initially be limited. The pattern eventually supports a northward
push of deep moisture as the low level flow veers and the h8 and
h7 becoming more favorable for locally heavy rains.

NAEFS has increased the PWAT to 2 to 3 standard deviations and the
integrated water vapor transport is 4 to 6 standard deviations
above normal across KS. We are still in the marginal to slight
risk for excessive rainfall with 1 to 2 inches of rainfall
forecast across the cwa. Decided to trim the FFA, but leave
intact next to TOP/EAX to raise awareness to the anomalous
conditions and potential for heavy rain especially late tonight
and Tuesday. Instability lifts across the areas Tuesday. We are in
a marginal risk for severe storms, however at this time, forecast
soundings do not show a lot of support, but there could be some
stronger storms ahead of the drier air being pulling in Tuesday
afternoon. Highs today mostly in the 50s with 50s and 60s for
Tuesday.

Showers could linger into Wednesday morning, otherwise look for
highs in the 70s.

.LONG TERM...(Wednesday night through Sunday)
Issued at 355 AM CDT Mon May 20 2019

The extended remains active with on and off thunderstorm chances.
A surface front Thursday through the weekend will be the focus
for more rain...some heavy...and some severe weather.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 616 AM CDT Mon May 20 2019

A few shower will affect KOFK for a couple of hours this morning.
Otherwise VFR conditions. Rain developing at all sites through
time, by 18z at KLNK and 20-23z at KOFK/KOMA. Conditions
eventually becoming MVFR by 03-06z, and even down to IFR at KLNK
by 08z. Thunder also possible at KLNK by 08z.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Flash Flood Watch from this evening through Tuesday evening for
     NEZ088>093.

IA...None.
&&

$$

SHORT TERM...Zapotocny
LONG TERM...Zapotocny
AVIATION...DeWald

NWS OAX Office Area Forecast Discussion

Forecast Discussion
NWS Hastings, NE

553
FXUS63 KGID 201150
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
650 AM CDT Mon May 20 2019

.SHORT TERM...(Today and tonight)
Issued at 409 AM CDT Mon May 20 2019

A band of light showers is lifting north across the local area
early this morning ahead of the main show...which is currently
lifting north out of the panhandle of Texas and headed our way.
While instability will begin to wane as it reaches the local area
this afternoon and encounters more stable air...it is not out of
the question that a few strong or a marginally severe
thunderstorms could be realized primarily across north central
Kansas as this activity initially moves into the local area. While
widespread severe weather is not a concern, could see some
marginally strong thunderstorm winds gusts and marginally severe
hail later today.

As these clouds, showers and a few thunderstorms move across the
local area...expect this to result in a cloudy, wet and cool start
to the work week, with a few locations potentially not climbing
out of the upper 40s by the afternoon hours. While there will
likely be some breaks in rainfall...expect more showers than dry
weather over the next 36 hours as this system passes...bringing
some significant rainfall to the area on the order of 2 inches in
the wettest spots...and plan to maintain the flash flood watch for
Mitchell county in Kansas for the time being.

.LONG TERM...(Tuesday through Sunday)
Issued at 409 AM CDT Mon May 20 2019

Model guidance is fairly consistent bringing the main area of low
pressure out of the southwest and across the local area Tuesday,
which could bring the potential for severe weather to the region.
While instability is fairly marginal...on the order of 1000 J/KG
at its peak...with the main low moving directly overhead, good
shear should allow for some organized storms and an increased risk
for severe weather across the local area. The main low will then
track into the Dakotas by Wednesday...allowing for a few breaks in
cloud cover and temperatures climbing back closer to normal.
Continued unsettled weather is expected through the end of the
week, however, as off and on again chances for showers and
thunderstorms will continue across the local area in the large
scale active southwesterly flow pattern.

With modest instability returning with a subsequent wave late
Wednesday night through Thursday, could see another period of
potentially strong to severe thunderstorms across parts of the
local area...and just about the entire area is presently outlooked
in day 4 from the storm prediction center. Thereafter...continued
periods of unsettled weather and near normal temperatures are
forecast to persist through the upcoming weekend and potentially
into early next week. Temperatures overall will start the week
below normal...and end near or slightly above normal by the
week.

&&

.AVIATION...(For the 12Z KGRI/KEAR TAFS through 12Z Tuesday)
Issued at 633 AM CDT Mon May 20 2019

MVFR CIGS have settled in at both terminals and are expected to
further deteriorate through the period. Expect some light BR and
SHRAs to develop during the late morning through afternoon hours.
Eventually...expect IFR CIGS and lower visibilities by early
evening as the brunt of the precipitation overtakes the region. At
the same time...winds will be increasing through the
day...gusting to near 30 KTS during the late afternoon through
evening hours today. Could also see a TSRA or two...primarily
during the early evening hours.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...Flash Flood Watch from 1 PM CDT this afternoon through Tuesday
     evening for KSZ019.

&&

$$

SHORT TERM...Rossi
LONG TERM...Rossi
AVIATION...Rossi

NWS GID Office Area Forecast Discussion