Damaging Wind in Arkansas, August 29, 2018

Area Forecast Discussion
National Weather Service Memphis TN
1235 PM CDT Wed Aug 29 2018

.UPDATE...

Updated to include 18z aviation discussion.

&&

.PREV DISCUSSION... /issued 1043 AM CDT Wed Aug 29 2018/

UPDATE...
Showers and thunderstorms have developed along and ahead of a cold
front this morning. Most of this convection remains to our north,
but a few showers have formed over northeast AR and the MO
Bootheel in the past 1-2 hours. This trend will continue today as
a shortwave trough moves across the Midwest. Lift across the Ohio
Valley is enhanced by the transverse circulation associated with
the right entrance to the strong upper-level jet downstream of
the parent trough. PoPs were removed south of I-40 through 18z,
but persist area wide this afternoon.

Hi-res CAMS continue to indicate the convection to our northwest
approaching Memphis this afternoon, gradually weakening as it
moves south into the upper-level ridge where shear is weaker and
stability is more pronounced. A few strong to marginally severe
storms are possible in the northwest zones this afternoon, but
this threat remains limited. In addition to the possibility for
strong storms, precipitable water values near 2" will support the
potential for localized heavy rainfall with any slow-moving or
training storms this afternoon.

Johnson

PREV DISCUSSION... /issued 355 AM CDT Wed Aug 29 2018/

DISCUSSION...08Z Surface analysis places a cold front from
Northern Lake Michigan back through West Central Missouri, Central
Oklahoma, and the Texas Panhandle. Meanwhile, a ridge of high
pressure is centered off the Southeast United States in the
Atlantic Ocean. Southerly winds on the back side of high pressure
is advecting warm and humid air into the Lower Mississippi Valley
resulting in surface dewpoints in the lower to middle 70s.
Temperatures as of 3 AM CDT are in the 70s with a few locations in
the upper 70s along the Mississippi River.

Short term models including Convective Allowing Model (CAM)
solutions indicate the aforementioned cold front will begin to
drop into northern portions of the Lower Mississippi Valley and
Mid- South later this afternoon into tonight. Model soundings
indicate main forcing mechanism for any shower and thunderstorm
development during the day will be convective temperatures being
reached during peak heating. As a result, isolated to scattered
showers and thunderstorms may develop with the best coverage
occurring northwest of I-40 over Northeast Arkansas around the
approaching front. Surface based CAPE values above 3000 J/kg,
overall weak shear less than 20 kts and precipitable water values
approaching 2 inches suggests potential for a strong thunderstorm
or two producing gusty winds and localized heavy rainfall.
Isolated to scattered showers and thunderstorms may linger into
tonight as the front drops into the area but may decrease in
coverage as instability decreases with the loss of daytime
heating.

Showers and thunderstorms are expected to develop across much of
the area Thursday with the front stalled out across the area.
Models indicate this front will retreat back north as a warm
front by Friday with an upper level ridge building across the
Southern United States this weekend into next week. Consequently,
a persistent humid airmass with afternoon highs in the upper 80s
to lower/mid 90s and lows in the 70s are anticipated along with
isolated showers and thunderstorms mainly during the
afternoon/early evening hours each day.

CJC

&&

.AVIATION...
18z TAF Cycle

VFR conditions begin the period as a front approaches the region
from the northwest. A few showers and storms are currently popping
up on radar, thus also begin the period with VCTS and VCSH and
all terminals. Used a TEMPO to time TSRA at the terminals, which
looks most likely between 21z and 01z. Southerly winds ahead of
the front will become more from the east and north overnight and
early on Thursday. Included TEMPO for fog formation during early
morning hours at KMKL and KTUP with light winds and a moist low
level. VFR conditions will end the period with lighter winds.

ZDM

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&

Hazardous Weather Outlook...UPDATED
National Weather Service Memphis TN
526 AM CDT Wed Aug 29 2018

ARZ008-009-017-018-026>028-035-036-048-049-058-MOZ113-115-
MSZ001>017-020>024-TNZ001>004-019>022-048>055-088>092-301230-
Alcorn-Benton MS-Benton TN-Calhoun-Carroll-Chester-Chickasaw-Clay-
Coahoma-Craighead-Crittenden-Crockett-Cross-DeSoto-Decatur-
Dunklin-Dyer-Fayette-Gibson-Greene-Hardeman-Hardin-Haywood-
Henderson-Henry-Itawamba-Lafayette-Lake-Lauderdale-Lawrence-
Lee AR-Lee MS-Madison-Marshall-McNairy-Mississippi-Monroe-Obion-
Panola-Pemiscot-Phillips-Poinsett-Pontotoc-Prentiss-Quitman-
Randolph-Shelby-St. Francis-Tallahatchie-Tate-Tippah-Tipton-
Tishomingo-Tunica-Union-Weakley-Yalobusha-
526 AM CDT Wed Aug 29 2018

This hazardous weather outlook is for portions of East Arkansas...
the Missouri Bootheel...North Mississippi...and West Tennessee.

.DAY ONE...Today and Tonight

A few strong thunderstorms to perhaps an isolated severe
thunderstorm will be possible this afternoon into tonight across
the Mid-South, especially across northeast Arkansas. Damaging wind
gusts and localized heavy rainfall will be the main threats.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

A few strong thunderstorms will be possible again on Thursday
across the Mid-South. Gusty winds and localized heavy rainfall
will be the main threats.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated at this time.