Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
SPC AC 272007
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0307 PM CDT Mon Mar 27 2017
Valid 272000Z - 281200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
WESTERN AND CENTRAL KENTUCKY...WESTERN AND MIDDLE
TENNESSEE...NORTHEAST MISSISSIPPI...AND NORTHERN ALABAMA...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
ENHANCED RISK AREA FROM THE OHIO VALLEY TO THE LOWER MISSISSIPPI
VALLEY TO ALABAMA...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
SLIGHT RISK AREA FROM THE OHIO VALLEY TO LOWER MISSISSIPPI VALLEY...
Scattered to numerous severe thunderstorms are expected across the
Lower Mississippi and Ohio Valleys into the Tennessee Valley this
afternoon and evening. Very large hail, damaging winds, and a couple
tornadoes will be possible.
Given the eastern progression of the midlevel shortwave trough and
the western portions of the severe-weather probabilities have been
trimmed eastward, while the Enhanced Risk for severe/damaging winds
has been expanded eastward some across central KY, middle TN, and
...Far southern IL, southeast MO and eastern AR...
Given the eastward progression of the midlevel shortwave trough, the
severe probabilities have been trimmed across parts of far southern
IL and southeast MO, and shifted east across much of central and
eastern AR and part of northwest MS, where the severe threat has
diminished. The exception is across northeast AR, where moderate
instability and sufficient bulk shear are maintaining a severe
threat with storms developing along the cold front.
...Northeast LA to northeast AL and northwest GA...
The severe probabilities have been expanded into more of northeast
LA/southwest MS and northeast AL into northern GA for an increase
severe weather threat than was forecast in the earlier outlook.
...Eastern KY into southwest WV...
A leading midlevel shortwave trough appears to be moving across
eastern KY and eastern AL into western GA. Forcing for ascent with
this trough and destabilization into eastern KY to WV suggests the
severe weather threat needed an eastward expansion.
.PREV DISCUSSION... /ISSUED 1130 AM CDT Mon Mar 27 2017/
...Lower Ohio/Mississippi River Valleys and Tennessee Valley...
A low-amplitude shortwave trough over the southern MO late this
morning will continue generally eastward and reach the middle OH
River Valley by late tonight. A preceding belt of 40-50 kt
west-southwesterly mid level winds will continue to overspread an
increasingly moist, albeit modestly so, warm sector. Ahead of an
eastward-moving cold front currently across the Ozarks and
Ark-La-Tex, lower/some middle 60s F surface dewpoints will continue
to become increasingly common across eastern AR, northern MS into
western TN, northward into western KY. While warm-sector cloud cover
has remained semi-prevalent thus far, some cloud breaks are noted in
visible satellite imagery an additional thinning seems likely in
concert especially with the eastward-spread mid/high-level dry slot
as per water vapor satellite imagery.
Linearly organized convection across far northeast AR/far southeast
MO late this morning should continue to spread east-northeastward
and increase in coverage/intensify into northwest TN and
western/central KY as the downstream air mass continues to moisten
and destabilize. This activity will pose a damaging wind and severe
hail risk, although a tornado cannot be ruled out. Farther south,
other initially more discrete storms should develop within the warm
sector this afternoon across additional portions of TN, far eastern
AR, northern MS and eventually northwest AL later this
afternoon/evening. Here, supercell-favorable wind profiles and steep
mid-level lapse rates as noted per 12Z observed soundings will
support large hail potential. A few tornadoes also appear possible,
particularly around mid/late afternoon into early evening across
western/middle portions of TN and northern MS and northwest AL. In
this corridor, a modest westerly component of the mid-level winds
will coincide with modestly strong low-level shear/SRH.
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z