August 5th Severe Potential

Severe potential or not is the question of the early morning hour. Well, lets look at the positives that we have for severe potential today.

Dewpoints in the 70s

Temperatures in the 90s

Trigger Advancing cold front

CAPE 1000-2000 higher pockets to the Southeast that are above 2000

Lift index about –2 to –4

Shear around 30 knots +

All the best parameters are equivalent to the zone in red…though the temperatures and dewpoints apply to basically the whole region.

Some negatives or potential negatives that need to be factored into the equation of severe weather or not…

Relatively thick cloud cover

Mid level lapse rates of around 5.5

Current radar showing convective rains across central PA into Western PA and then into NY as well. Could this cause the atmosphere to become a little more stable and perhaps with the cloud cover leave some subsidence behind?

All and all I think the best chances for severe weather are going to be south of the PA border. This does not mean that severe will not occur further to the north just i think that the greater chance is the further south you go.

Any storms that do occur will have the potential to drop very heavy rain as precipitable water is over 2 inches in parts of the region. So some flash flooding and local and urban flooding is possible. Because of colder air aloft over the far NE there could be the potential for hail. Other wise the main aspect of severe weather will be the wind potential.

Remnant COLIN thoughts

Conditions are still not exactly what i would consider as favorable for COLIN and this is probably the reason why he is not able to get a defined surface circulation going.
Granted this is all based off of 3 Z information but it is the information that we have until 6 Z would become available but that would not be till close to 8Z.

Upper Level low is essentially moving in Tandem with what is the remnants of COLIN. This ULL is providing shear but because the remnants are on the east side its also helping to fire off convection. However...the system is under between 10 to as much as 30 + knots of shear..

So this shear is helping to actually cause the northern part of the system to be sheered off and the convection on the northern end keeps warming and fading out. It also continues to fight against dry air on its western side as well as its eastern side.

This is the shear tendency map and you can see what is either to the north or NW of the remnants of COLIN. Essentially increasing shear. So the environment is not going to get any better with the direction that his leftovers are heading.
Then also the size of this system being broad is also another factor that is going to slow down any potential development.
The other factor that I think may also come into play here is with the MJO

While the MJO is still in the center ...the MJO as of the 3rd actually took a right hand turn instead of a left and appears to be heading over towards phase 5 potentially.
Basically until the ULL gets out of the way and the shear subsides any development should be slow to occur.

Invest 92 L thoughts

Note this information is based on 15 Z as 18 Z will not be available until an hour after 18 Z

As of 15 Z this invest is in 10-20 knots of shear with the best convergence off to its west. So at that time it was not in an area of good convergence. Divergence is a different story however. The vorticity area is elongated and stretched out.

You can see on the most recent water vapor image that this is another large tropical wave and the system is pretty stretched out. There is some good convection involved but because of the diurnal minimum its not as good as what it was in the overnight period. Movement is due west with this system. Larger systems have a slower time of developing so any development with this system should be slow to occur.
Right now I would put the chances of this developing between 10-20 %

August 4th Daily Weather Discussion

High temperature on August 3rd at KABE was 84 degrees. This was seasonal for this time of the year as normal high is 84 degrees.

Unfortunately today is going to be a day where the humidity increases. It actually started yesterday but the temperatures remained comfortable. Temperatures today are going to be starting out on the warm side from the overnight lows the night before only going into the 70s. Highs today are generally going to  be in the mid to upper 80s but some locations may see the lower 90s.

Weather wise is going to be partly to mostly cloudy with showers and thunderstorms possible. Maybe some isolated severe storms in extreme western PA…possibly extending into central pa..Otherwise just your normal day time convective heating storms due to some weak disturbances moving across the region.

Ahh Its Invest 91 Time

Well, invest 90 became no more and we shifted east a couple hundred miles about 200-300 to be precise and we have now highlighted invest 91 L.

Earlier yesterday NHC had upgraded to an 80% chance on developing into a Tropical Depression. Earlier yesterday on the internet i made a comment that i would with hold any thoughts in reference to that upgrade.

Well lets look at the reasons why…

The above is from August 1st at 4:45 UTC

This picture above is from August 2nd at 4:45 UTC just twenty four hours later. Now which image has the deeper convection? Photo # 1. Which image has a closed low? Or a defined center of circulation? That would be neither image. So we have NHC saying at  2 PM this afternoon that a Tropical Depression maybe forming and up the chances to 80%..and then 90% . So 12 hrs later there is still not a tropical depression forming despite there words of it appears a tropical depression is forming at 2 PM yesterday. Despite the fact that at the time of saying this convection was waning..despite the fact that 12 hrs later they are saying that there is no defined center of circulation. So the ultimate question once again towards NHC..is praytell how you can have a tropical depression forming without a defined center of circulation? The answer is you can not have a Tropical Depression without a closed low!

So lets look at conditions now. We are currently in 10-20 knots of shear..While this can still develop in shear of that range..more favorable would be 5-10 knots.

The system is also as of 3 Z no longer in the best convergence, or the best divergence.

As both of these area lie to the North of the system. Its also not located in the best vorticity area as that is off to its Northeast..

The system does not really have any deep convection with it...and let me introduce you to what looks like another tropical wave on the right hand side of the water vapor just getting into the image You can see the water vapor image above. This could very well cause a competing dual between the two waves, which ends up getting the energy? This has been seen multiple times this season already...
And there is still dry air off to its north...NW...NE ..Factor in it is a large system..and larger systems take longer to develop and spin up.

So all in all i think NHC did jump the gun on development and would put the chances over the next 24-48 hrs at 50 %.

August 1st Daily Weather Discussion

The last day of July came in with a high temperature of 82 degrees. This was day 2 of below normal temperatures after the blistering heat that we had.

Today is going to be a mostly cloudy day across the region with a chance of showers and thunderstorms. Any storms may contain heavy rain.

Temperatures today are going to be on the cool side once again with highs mainly in the 70s to lower 80s across the northeast to MD…

Latest thoughts on 90 L which is no longer 90 L which would become 91 L

Well, not to rehash what has been already said and stated around the internet, but since 90 L was deactivated and declassified earlier yesterday this would not be 90 L. Another reason this would not be 90 L was when 90 L was first highlighted at 20 % making it an invest it was 600 miles from the islands. This is 850 miles from the islands. So we have shifted 250 miles east and since waves move off the African Coast in a east to west fashion this can not and could not be 90 L.

The above is a still image of the water vapor. Like i said while speaking to Carlos.. this is one tool that i love and can not ever get enough of.
First thing you are going to notice is the rather far south position of this wave. Well, that is because it is essentially from what i can see still part of the ITCZ. I have highlighted some things. First to the North is the huge ULL. Second is the ton of dry air to its north. Dry air is denoted on the water vapor images by the orange color. Third thing is i have drawn a yellow line. From approximately the center of this wave and south it is now involved in and under 10-30 knots of shear.

Essentially because this system is so far to the south and essentially still part of the ITCZ the movement also indicated on the WV image and also indicated by NHC is due west. If this movement does not change and if this system does not pick up latitude ..you can essentially say hello to South America. However..if it does actually gain some latitude then off to its NW is all that dry air. So it really is a catch 22.
Now i have seen comments in reference to the GFS being the most consistent with this system. Perhaps consistence can be viewed as a plus with the model but only if it is not being consistently wrong.
How is it going to intensify a system the way it does...with it being in strong westerlies from an ULL?

Image courtesy of (click here)

This simply is not a possible happening. So basically we can toss the GFS out the window at this point and time...
Operational GFS

GFS ensemble mean

Quite the difference between the two at the same time frame.

While the MJO could enhance convection with this system..its heading towards the COD which is neutral for when it comes to tropical cyclones & there development. It would be much better if this were in Phase 1 or Phase 2 but being its headed into the COD this does not spell out the best development potential.
So with all the above factors in play, any development will be slow to happen.