Valid 272000Z – 281200Z
…NO SEVERE THUNDERSTORM AREAS FORECAST…
…SUMMARY…
Isolated thunderstorms may occur today across parts of the Great
Lakes, Northeast, and Mid-Atlantic, as well as portions of
California. Severe thunderstorms are unlikely.
No changes to the previous outlook regarding the lack of severe
weather potential.
..Jewell.. 11/27/2019
.PREV DISCUSSION… /ISSUED 1029 AM CST Wed Nov 27 2019/
…Synopsis…
An intense midlevel shortwave trough over the Great Lakes/upper OH
Valley will move eastward over NY/PA by this evening and southern
New England overnight. Ascent within the warm conveyor belt, in
combination with weak buoyancy rooted near 700 mb, will support a
threat for isolated thunderstorms today across PA/NY, and southern
New England this evening. Farther south, isolated thunderstorms
have occurred this morning along the trailing cold front from
southern LA to southeastern AL. The lingering overlap of stronger
low-level shear along the northeast edge of the unstable surface
warm sector is diminishing now, which is bringing an end to any
threat for rotating storms.
A deep midlevel trough continues to dig southward along the CA
coast, with cold midlevel temperatures/steep low-midlevel lapse
rates contributing to weak buoyancy and the potential for isolated
lightning strikes today. A separate midlevel trough southwest of
the Baja Spur will eject northeastward to northwest Mexico and
weaken through tonight. A subtropical moisture plume preceding this
ejecting trough will contribute to widespread precipitation later
today into tonight from southeastern AZ into NM/west TX/OK. Some
embedded midlevel convection will be possible, and very isolated
lightning flashes may occur. However, poor lapse rates aloft and
minimal buoyancy suggest that the thunderstorm threat is too
marginal for an outlook area from the AZ/NM international border
area into central TX through tonight. The only other area with any
concern for thunderstorms will be along the lower/middle TX coast.
Here, weak warm advection will develop later today into tonight as a
front stalls across the shelf waters. Some shallow convection is
likely in this regime, but the cap should be strong enough to limit
the threat for deep convection/lightning.
$$