The Dot is where we have the greatest confidence for strong/severe weather. This is for entertainment and forecasting study purposes. For an official outlook visit www.spc.noaa.gov.
The "Dot" is over Indianapolis, IN/ And rest of Midwest
This area will be under scattered to widespread because of the severity of the threat. Widespread activity is not likely but scattered is and the severity of this activity could mean tornadic activity along with damaging winds and large hail. The threat is going to revolve around a sfc low that will be positioned at Central IL/IN border at 1pm CDT and at Central IN/OH at 7pmCDT. The reasoning is the backing winds at the sfc with westerlies aloft. This is going to result in bl-6km shear values approaching 35-40kts in a diffluent flow aloft supporting supercell development. Strong forcing exist along the front the wave will ride along which could do a few things. As diurnal heating continues along the front I expect initial development of supercellular storms to become semi-discrete or undergo upscale growth into an MCS as they reside along the boundary. As the sfc low progresses eastward we should see a mixed mode of line segments and supercells discrete/semi-discrete. The 0-1km vertical shear is impressive with values exceeding 20Kts and strong veering profiles with height. SFC based CAPE to the north of the boundary will greatly enhance tornadic potential as storms move across. Sfc winds back to the east greatly increasing low level vertical shear in an environment supportive for sfc based convection.
New York into New England
I decided to keep the blue over this region for several reasons. The greatest shear/instability combination exist over this region and it is also in the presence of several lifting mechanisms. Several embedded pieces of s/w energy will round the edge of the mid level trough interacting with 1) frontal boundary 2) lake breeze boundary 3) sfc trough. I think enough forcing exist combined with forcing and low lfc heights/low level shear orientation for a few organized line segments to progress through this area with a damaging wind threat. Secondary threat will be for large hail up to 1.50" in diameter.
We are going to watch a few things for the Middle Atlantic. One is a MCV currently over IN that will be somewhere in the Northeast or Middle Atlantic. The ascent of this feature will combine with favorable instability to produce strong to severe activity somewhere in the Northeast. Track of this feature is uncertain. A sfc trough will exist from VA up to PA where the slightest of convergence will ignite thunderstorm activity along with higher terrain given convective temperatures will be reached. As the sfc trough pushes east activity should remain loosely organized allowing for isolated to scattered severe. The sea breeze has my interest again for tomorrow. Weak low level winds will aid in development along sea breeze front but will hinder organization along sfc trough for most part. The stronger sfc winds will aid in lift along the sea breeze front where convective temperatures will be reached allowing for a rough day for some at the shore. Marginal mid level lapse rates combined with dry air and ample CAPE aloft will result in a threat for large hail up to 1.50" in diameter in the strongest storms that form. Damaging winds and flash flooding will be the main concerns.
Had to shift threat east a little bit today as front will clear previous areas highlighted yesterday. But the strong convergence along the front will be sufficient enough beneath 20-30Kts of bl-6km vertical shear for organized multicells. Arkansas will be in the jackpot where CAPE values will exceed 3500J/Kg with focus along a pre frontal trough and the front in close proximity. Steep mid level lapse rates and a well mixed BL will contribute to primary threat of damaging winds.
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