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July 14-16 Flash Flood Watch & Warnings


bluewave

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A closed low is forecast to move to the Great Lakes early next week with an associated

cold front slowly approaching the East Coast. This digging closed low will pump the 

Western Atlantic Ridge to our east and cause the cold front to stall near the region.

This will be a tropical airmass with PWATS approaching 2.00". The models typically 

underestimate rainfall totals when training convection is involved. So the model max totals

in the 2-3 inch range may be conservative for locations that experience training 

of cells as the upper flow becomes parallel to the front under strong upper divergence.

The other point to realize is that areas from NYC west have experienced well above

normal rainfall for July to date.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Flooding looks to be the main threat early next week. The activity is going to be too widespread and too numerous to support much discrete development. I supposed that we could see a few strong squall lines or MCS which will be very hard to forecast more than a few hours in advance.

 

More than half of the 00z ECMWF ensemble guidance was spitting out > 3" totals with only 9/51 members showing under 2".

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Caldwell Airport is currently running 97% above normal for the month precip wise and areas just to my north are running well above normal as bluewaves graphic indicates while places closer to the coast have been running near normal or even below normal. Quite a NW to SE gradient currently in the area. Current 6 hour flash flood guidance is under 2" in alot of locations in northern NJ.

 

xhr6.png

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Like snowstorms there will be jackpot zones and areas of MUCH less, i know training setups usually favor E.PA and NJ up to LHV.

Monday to Tuesday evening favor areas west of NYC before the focus shifts to eastern areas late Tuesday and into Wednesday morning. That's if the front does indeed make it that far east.

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Going to give the dallies on the 12z ECMWF since people will ask.

 

Saturday - Pleasant and Sunny

 

Sunday - Storms fire over NNJ and the LHV between 12z and 18z. Then slowly sag southeastward and expand. Lots of training over northeast and northern NJ and then up into western New England. Then dissipating after sundown before making it to the city. Rainfall between 0.50" and 1.00" with locally higher amounts in training thunderstorms.

 

Monday - Early morning convective debree and and a few showers then another line of showers and storms crosses the region between 12z and 18z from NW to SE. Some areas may stay dry on Monday based on the Euro.

 

Tuesday - Large convective complex forms before 12z with the city getting clipped on the northern fringe. Then nails eastern Long Island hard. Then a very strong area of convection forms on the front, possibly a MCS. That crosses the area from SW to NE between 12z and 00z. The high res Euro is showing a 3" bullseye in 6 hours over Westchester County which it very rarely shows. Then another round comes through between 00z and 06z Wednesday with western Long Island getting pummled.

 

SW CT is the jackpot zone with 5.5"+ and most other areas in the 2-3" range.

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Tuesday night looks really good in your neighberhood

ecmwf_slp_precip_boston_20.png

We all know it's very hard to predict rainfall amounts and models don't do a great job with it. It really isn't a great idea talking about numbers when dealing with convection. With that said my area needs the rain. I will gladly take it. The weather has been mostly pretty perfect but I need a change for a couple days.

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I think we're looking at a very high probability of heavy rains throughout the Northeast corridor. Closed/nearly closed low in the Great Lakes with a retrograding west atlantic ridge should enhance convergence over the region. Furthermore, the strong upper jet streak is positioned such that we're located in a favorable quadrant for upper divergence and low level convergence (right entrance region of streak).

 

As it's currently timed on the ECMWF guidance, I like Tuesday into Wednesday morning for most widespread heavy rains. Sunday-night into Monday could produce scattered hvy convection as well.

 

33xeic6.png

 

 

10sdbvq.png

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