Severe Weather Update

We are going to make no changes for the map that was already issued for monday into tuesday as that looks to still be on track as far as timing wise. Essentially looking at the latest guidance from the ECM to the GFS..it appears as though the cold front will be crossing the region between 00z tuesday and 6 Z tuesday…

Looking at the latest severe weather parameters off the 12 Z GFS

Shear is more then ample with anywhere from 25 knots to 50 knots with some isolated higher amounts.

Lift index is between –2 and – 4 . Some might ask why Lift index is important? The answer is the Lift index shows whether the atmosphere is stable or unstable. For severe thunderstorms you need a negative value . In this case we have –2 to –4 which means:

LI Between -2 and -6 : Unstable, Thunderstorms Likely, Some Severe With Lifting Mechanism

CAPE or Convective Available Potential Energy

The energy that is available is showing around 1000-2000 CAPE. This is more then sufficient to suggest that we could have severe weather.

Lapse rates are between 6.0 & 6.5 . The more higher the # the more instability. So these are marginal at the present time. Generally i like to see lapse rates of 7.0 or above.

Now another added ingredient that we are going to have this time, as it now appears is daytime heating:

As you can see the inland locations have the heat turned on with temperatures generally in the 70-80 range or 80-90 range. Now just because you see those ranges does not mean that your temperature is going to be 90 or in the 90s. It means that it will be in that range and for specific temps you should always refer to your soundings for your location off the weather models.

Unfortunately along the coast there is going to be a persistent onshore flow and this will help serve to keep the real heat away from those locations and keep temperatures more in the 60s to around 70.

The one thing that is indeed missing from this whole scenario however is an extreme drop in temperatures behind the front. There is not really any colder air coming in with this cold front. Temperatures will drop but they are only going to be dropping into the 60s. So this could impend the otherwise spark that would be there.

Never the less with the day time heating involved and the parameters in place and the timing being slightly better then the last time..we feel that this go around has a better chance to bring severe weather further to the north.

Severe weather expected would be Winds in excess of 50 MPH as the main potential. There could be the threat for some isolated tornados as well. Again the best chances for this will probably be inland from C PA to E PA to NY State.

Stay tuned for further updates!