Flash Flooding and Damaging Winds in Arkansas, July 1 to 3, 2020

Area Forecast Discussion...UPDATED
National Weather Service Little Rock AR
624 AM CDT Wed Jul 1 2020

.UPDATE...

Updated to include 12z aviation discussion below.

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.AVIATION...

MVFR/IFR ceilings in place this morning will persist through the
morning hours before giving way to VFR ceilings. Winds today will
be out of the SW, generally 10kts or less with a few higher gusts.
Potential for RA/TSRA highest across NE AR this afternoon,
elsewhere little coverage is expected.

&&

.PREV DISCUSSION...(ISSUED 335 AM CDT Wed Jul 1 2020)
SHORT TERM...Today Through Thursday Night

H500 ridging will be expanding northward from the Southern Plains
toward the Great Lakes region and intensifying somewhat today and
tomorrow. The center of the high will likely reside over eastern
Oklahoma, which will keep much of the state dry over the next 24
hours at least. With the high expanding northward and persistent
low pressure across the NE US, H500 flow across eastern Arkansas
and adjacent areas across the MS River will be sharply out of the
north.

Several shortwaves will traverse the steep flow aloft and with the
aid of a nearly stationary boundary, oriented in a similar
fashion just NE of the forecast area, a few rounds of showers and
thunderstorms are expected to develop. Much of this activity will
remain outside of the CWA, but have increases POPs a bit to
highlight the increased likelihood of a few thunderstorm complexes
skirting the area.

With the ridge expanding, sfc temperatures will increase across
the state the next couple of days with Thursday potentially being
the hottest day of the year in some locations. With such a moist
airmass in place at the sfc, providing Td values in the mid to
upper 70s F, heat related concerns will be elevated as apparent
temps will likely climb into the 105-110 range in many areas. Some
sites may approach Excessive Heat Warning criteria Thursday, this
will have to be monitored during subsequent shifts.

Have continued the Heat Advisory areawide through Thursday, but
given the close proximity to rain and cloud cover, northeastern
areas could remain below advisory criteria. On the other hand,
timing dependent, locally enhanced moisture could inflate Td
values which would help produce advisory level heat indices with
temperatures that aren't quite as hot as forecast values.

LONG TERM...Friday Through Tuesday

The weather pattern can be characterized as unsettled to begin the
long term. Aloft, an omega high over the north-central Plains will
already be in the process of breaking down and retrograding. At the
surface, high pressure over the portions of the Great Lakes will
follow in tandem with the upper level ridge. A weak/mesoscale
trough will be localed over portions of the Appalachian Mtns which
will follow suite and retrograde with both the aforementioned
upper- level/surface features.

Over AR, this will promote upper level shortwave energy to traverse
the periphery of the ridge and through the base of the trough at
irregular intervals during the period. Surface convergence should
promote sufficient forced ascent and when combined with upper level
vorticity, to produce periods of showers and thunderstorms.
Precipitation chances over the weekend will greatest over
southwestern/southern AR, however much of AR will see slight chance
PoPs. Chances of precipitation across AR early next week will be
greatest during the afternoon hours with the aid of diurnal heating
combined with weak surface convergence. Overall, no organized large
complexes are expected at this time, thus any severe weather is
expected to be isolated in nature.

Temperatures will top out near or just above the 90 degree mark each
day. Dew points will remain fairly high despite weak northeast flow
through much of the weekend into the first half of next work week.
Heat indices will range from 95 to 100 degrees each afternoon. The
highest values are expected over the Delta region and much of
central and southern portions of the state. This will still come as
a small relief compared to the short term periods expected heat
indices.

&&

.LZK Watches/Warnings/Advisories...
Heat Advisory from noon today to 7 PM CDT Thursday FOR Arkansas-
Baxter-Boone-Bradley-Calhoun-Clark-Cleburne-Cleveland-Conway-
Dallas-Desha-Drew-Faulkner-Fulton-Garland-Grant-Hot Spring-
Independence-Izard-Jackson-Jefferson-Johnson-Lawrence-Lincoln-
Logan-Lonoke-Marion-Monroe-Montgomery-Newton-Ouachita-Perry-Pike-
Polk-Pope-Prairie-Pulaski-Randolph-Saline-Scott-Searcy-Sharp-
Stone-Van Buren-White-Woodruff-Yell.

&&

Aviation...67

Hazardous Weather Outlook
National Weather Service Little Rock AR
344 AM CDT Wed Jul 1 2020

ARZ003>008-012>017-021>025-030>034-037>047-052>057-062>069-021000-
Boone-Marion-Baxter-Fulton-Sharp-Randolph-Newton-Searcy-Stone-
Izard-Independence-Lawrence-Johnson-Pope-Van Buren-Cleburne-
Jackson-Logan-Conway-Faulkner-White-Woodruff-Scott-Yell-Perry-
Polk-Montgomery-Garland-Saline-Pulaski-Lonoke-Prairie-Monroe-Pike-
Clark-Hot Spring-Grant-Jefferson-Arkansas-Dallas-Cleveland-
Lincoln-Desha-Ouachita-Calhoun-Bradley-Drew-
344 AM CDT Wed Jul 1 2020

This Hazardous Weather Outlook is for a Large Part of Arkansas.

.DAY ONE...Today and Tonight

Hot temperatures and increased humidity will cause heat index
values to climb into the 105-110 range across much of the area.

Isolated to scattered thunderstorms will be possible across mainly
northern and eastern portions of the state later today and
tonight. Widespread severe weather is not anticipated, but
stronger storms could be capable of producing strong wind gusts and
locally heavy rainfall, which could lead to flash flooding.

.DAYS TWO THROUGH SEVEN...Thursday Through Tuesday

The threat for organized severe weather will remain low through much
of the period. Scattered showers and thunderstorms are expected
daily with the best chances during the afternoon through early
evening hours across Arkansas. While a few stronger storms can not
be ruled out, locally heavy rainfall and isolated strong wind
gusts are the only concerns.

With abundant moisture in place at the surface and temperatures
expected to climb into the 90s, heat indices are expected to exceed
105 across much of the state on Thursday, with some locations
seeing heat indices above 110. Slightly drier air will arrive by
Friday and continue through the weekend reducing heat indices
below the 105 degree mark through Tuesday.

.Spotter Information Statement...

Spotter activation will not be needed.

&&

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