559
FXUS63 KOAX 070909
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
409 AM CDT Tue May 7 2024

.KEY MESSAGES...

- Marginal risk of severe thunderstorms Wednesday afternoon and
  evening northeast Nebraska and western Iowa

- Light showers and a few rumbles of thunder linger through the
  end of the work week, with drier conditions and highs in the
  70s returning for the weekend.

&&

.DISCUSSION...
Issued at 408 AM CDT Tue May 7 2024

Today: Complex of thunderstorms that brought severe weather to
the area has moved well east of the forecast area. Surface cold
front and pre-frontal trough located across western periphery of
forecast area. Low level moist advection continues. Combined
with wet soils from Tuesday night rains, there is a small window
for for development early this morning given clearing skies
across the area. Will monitor over the next few hours, but left
mention of any patchy fog out of the forecast for now.

A quiet day weatherwise is expected today. A broad H5 trough
will be in place across the northern plains, anchored by a
closed H5 low over the Dakotas. Weak disturbances rotating
around the trough, aided by diabatic heating will aid in the
development of isolated to scattered sprinkles/showers this
afternoon into early evening. Seasonal temperatures are
expected.

Tonight: Aforementioned H5 low and trough syncs with North
Atlantic vortex and digs south-southeast overnight as upper
level jet rotates around base of vortex. This will allow for
isentropic ascent and sharpening midlevel flow. Expect scattered
showers/isolated thunderstorms to develop, though dry low level
may limit precipitation from reaching the ground.

Wednesday:

Upper low begins to eject northeastward during the day on
Wednesday, with a broad upper level jet of 50-70 knots
persisting through the day, resulting in bulk shear 35-45kts.
Expect mid- level lapse rates to increase, especially across
northeast Nebraska and northwest Iowa as cold-core from upper
low moves across the area. At the surface, an inverted trough
will move across the forecast area, advecting a narrow band of
greater thetae into eastern Nebraska and western Iowa. A few of
the CAMS develop a narrow ribbon of 1000-1500 J/kg CAPE. In
tandem, expected thunderstorm develop during the afternoon, with
possibility of isolated severe storms. HREF hinting at potential
for a few rotating storms. Increased clouds and precipitation
chances will keep high temperatures a few degrees cooler,
especially northeast Nebraska and northwest Iowa.

Thursday-Friday:

Upper low transitions to open wave as it completes syncing with
North Atlantic trough. Cyclonic flow will remain in place across
the area, continuing chances for showers and isolated
thunderstorms on Thursday. Low level cold advection will keep
temperatures in the 60s. A more pronounced shortwave feature
drops southward from northern plains on Friday afternoon.
Downslope low level flow will help bump temperatures back into
the 70s for highs. Afternoon shower and thunderstorm
development again will be possible, possibly a little more
vigorous as passage of shortwave will occur during peak diabatic
heating.

Saturday Onward:

Upper level ridging builds across the area, bringing an end to
precipitation chances. Seasonal temperatures are expected.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1125 PM CDT Mon May 6 2024

Strong to severe storms will continue to push east of the
forecast area tonight. VFR conditions will prevail behind the
departing storms. Light WSW winds will become gusty after 15Z
tomorrow, occasionally reaching speeds of 20-30kts. Winds will
weaken again to under 12kts after 00Z Tuesday evening.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.

&&

$$

DISCUSSION...Fortin
AVIATION...KG