Mesoscale Discussion 342

Issued

Mar 27, 2017, 11:26 AM CDT (16:26 UTC)

Expired

Mar 27, 2017, 2:00 PM CDT

In force

3 hr

Issued by

the Storm Prediction Center

Chance of a watch

60%

The Paducah radar (KPAH), 111 km from the middle of the area, began a volume at 16:28 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

• Severe Thunderstorm Watch 89Mar 27, 12:05 PM CDT
• Severe Thunderstorm Watch 91Mar 27, 2:25 PM CDT

875 
ACUS11 KWNS 271626
SWOMCD
SPC MCD 271626 
TNZ000-KYZ000-ILZ000-MOZ000-ARZ000-271900-

Mesoscale Discussion 0342
NWS Storm Prediction Center Norman OK
1126 AM CDT Mon Mar 27 2017

Areas affected...Northeast Arkansas...Far Southeast
Missouri...western and central Tennessee...southwestern and
south-central Kentucky

Concerning...Severe potential...Watch possible 

Valid 271626Z - 271900Z

Probability of Watch Issuance...60 percent

SUMMARY...A severe threat appears likely to develop by early
afternoon across parts of the mid Mississippi Valley extending
eastward into south-central Kentucky and middle Tennessee. As cells
gradually intensify, wind damage and isolated large hail will be
possible. WW issuance will may be needed by 18Z across the region.

DISCUSSION...The latest surface analysis shows a surface low in
southwest Missouri with a cold front located southwestward from the
low. A warm front extends eastward from the surface low across
southern Illinois and west-central Kentucky. A line of thunderstorms
is ongoing in northeastern Arkansas located along a gradient of
low-level moisture oriented from west southwest to east northeast.
Moderate instability appears likely to develop along this corridor
over the next few hours. The line of storms is also located just
ahead of a shortwave trough on the southeast side of a pronounced
vorticity max. As the shortwave trough moves eastward, strong
large-scale ascent and continued surface heating will provide
support for a gradually increase in convective coverage. 

In addition, the RAP is analyzing a mid-level jet from northwest
Mississippi extending northeastward into western Kentucky. This
feature is helping to create moderate deep-layer shear profiles with
0-6 km shear in the 35 to 40 kt range as evidenced by the Paducah
and Nashville WSR-88D VWPs. The wind shear environment should be
favorable for severe thunderstorm development with bowing line
segments and supercells both possible. The current thinking is that
the line of storms in northeast Arkansas will gradually expand in
length from north to south. The line should obtain a severe threat
by early afternoon as it moves across northwest Tennessee and
western Kentucky. Additional thunderstorms with a wind damage and
isolated large hail threat may develop ahead of the line from
northern Mississippi into western and middle Tennessee.

..Broyles.. 03/27/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...LMK...OHX...PAH...MEG...

LAT...LON   35208763 35168955 35259010 35399049 35539078 35839093
            36269086 36669056 37178858 37288763 37408654 37308579
            36878544 36028542 35488593 35208763

Mesoscale Discussions in Tennessee, 2017Mesoscale Discussions in Kentucky, 2017Mesoscale Discussions in Arkansas, 2017Every mesoscale discussion in 2017

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.