SHORT TERM [Monday Through Wednesday]...
The progressive longwave trough will continue across Ern states and
amplify further on Monday as a series of impulses/vort max moving
NEWD across OH Valley and SE states with its attendant height
falls.this will develop cyclogenesis early with low lifting NEWD
across OH Valley then PA and into NE states with trailing cold front
initially moving slowly then racing across NE Gulf region during the
aftn and eve as a series of shortwaves race NEWD over Ern Conus.
The PoP will increase Monday to about 70% at Dothan & Albany, 60% at
Tallahassee, and only 40% at Cross City. Total STP not impressive
less than one inch.
The Storm Prediction Center has outlooked AL/GA portions of our
forecast area in a "Slight Risk" (15% probability of a severe storm
within 25 miles of a point, 5% for the rest of our area). Strong mid
tropospheric winds of 60-70 KT and a marginally unstable airmass
(SBCAPE around 500 J/KG) and increasing dew points in the
pre-frontal warm sector favor at least some storm organization.
However, models, especially NAM and ECMWF suggest a gradual decrease
in coverage and intensity of convective band ahead of cold front as
it moves Ewd and the stronger forcing moves towards OH Valley.
Amount of cloud cover could be a determinative factor in instability.
The lack of phasing among the multiple short waves creating a
marginal thermodynamic environment that seems to be preventing this
setup from being a more significant event for our area, as the main
500 mb short wave will be up in the Ohio Valley as it goes
negatively tilted Monday afternoon. Additionally, the forecast 850
mb jet is not forecast to be that impressive for this time of year
(only 40-45 KT), and its core will be just north of our forecast
area. The fairly unidirectional, deep southwest wind field and
unimpressive 0-1 km shear magnitudes suggest that our main severe
threat will be isolated damaging straight line wind gusts in
isolated bowing segments along the convective bands, similar to what
we observed last week with the frontal system just to our north. The
tornado threat appears low, and would be limited to brief,
relatively weak "spin-ups" at the ends of stronger bowing segments.
Beginning Mon night, flow aloft quickly becomes zonal as trough
exits into Atlc. In wake of front, surface high builds into
the central gulf on Tues then moves rapidly Ewd Tues night to
reach coast on Wed ahead of next system. Rain chances will diminish
Monday night (20-30%) as the cold front exits. Despite the frontal
passage, temperatures will remain warm through the period, with
lows in the 50s and 60s, and highs in the 70s ahead of next