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Could be another heavy rain setup Saturday-Monday, but that is dependent on which model is correct in handling with bermuda high and trough location and speed to the west. 

 

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Welcome!! And great 1st post! I’m guessing you have some kind of 1st responded/military background due to your military clock usage?! Haha   -only use the HRRR inside of 6-8 hours. Beyond th

nice write up Bri

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1 hour ago, tombo82685 said:

Could be another heavy rain setup Saturday-Monday, but that is dependent on which model is correct in handling with bermuda high and trough location and speed to the west. 

 

 

 

Nice job breaking down the setup differences with the GFS and Euro models. Might actually have learned something. 😉 Keep it up!!

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On 7/13/2021 at 6:53 PM, tombo82685 said:

Could be another heavy rain setup Saturday-Monday, but that is dependent on which model is correct in handling with bermuda high and trough location and speed to the west. 

 

Any updated thoughts on the weekend or still too early to make a guess?

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Hi Guys,

First time poster long time lurker, big fan of blizzards.  I am overseeing a sporting event on Saturday night in Philadelphia from 17:00-22:00 and we know at some point we are going to be hit by rain/thunder.  I know on the twitter account there was a comment on the Union game having issues, but that doesn't start until 19:30.  I'm very amateur compared to the regular phillywx crew; but looking at the shorter-term models, there seems to be a pretty big spread on storm arrival between the RGEM, NAM, and HRRR.  Any thoughts on why and how you typically weight these models?  Is the HRRR even worth looking at more than 24 hours out?

Thanks!

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8 minutes ago, JLS4628 said:

Hi Guys,

First time poster long time lurker, big fan of blizzards.  I am overseeing a sporting event on Saturday night in Philadelphia from 17:00-22:00 and we know at some point we are going to be hit by rain/thunder.  I know on the twitter account there was a comment on the Union game having issues, but that doesn't start until 19:30.  I'm very amateur compared to the regular phillywx crew; but looking at the shorter-term models, there seems to be a pretty big spread on storm arrival between the RGEM, NAM, and HRRR.  Any thoughts on why and how you typically weight these models?  Is the HRRR even worth looking at more than 24 hours out?

Thanks!

Welcome!! And great 1st post! I’m guessing you have some kind of 1st responded/military background due to your military clock usage?! Haha

 

-only use the HRRR inside of 6-8 hours. Beyond that, it’s prone to big swings. 
 

- NAM can get weird too outside of 48 hours. 3k NAM I use for about 36-48 hours out. I barely look at the RGEM . 
 

any higher resolution model tends to be fickle outside that 48 hour timeframe. Especially any CAM’s (Convection Allowing model, EG; 3k NAM, wrf etc). 
 

Gfs tends to be progressive/faster biased, while euro is slower. So most times, if there both doing there bias thing,a blend can work best for timing. 
 

Looking at Saturday: we’ll have a pretty humid, high cape environment. Not the best shear/flow, but we do have an approaching shortwave approaching from the west. Then we have to see about about a lee-side trough triggering storms early, as what usually happens in these uncapped, unstable environments. 
2D40D39A-5CE6-4B82-B884-627B65417A5D.png.fda697cf65c1eff1b72124e72e264bf9.png
 

-2500-3000jnCape

-Total totals around 48.. not bad, not great. 
 

- 25 knots effective shear. Not the best, but some deeper mid level shear could stop storms from collapsing in on themselves. (Organize a bit better)

In simpler terms? Looks like maybe a few different “rounds/opportunists” for storms to fire. Some pre-frontal stuff, which would use up the best thermodynamics, but missing the best lift. This would be scattered hit or miss stuff around in the afternoon- evening. 
 

And then the “main show”. With the approaching front later on in the evening (6-11). 385677AA-1B2C-469D-B38B-A6029B68FD8D.png.d6daf4e6e3b150c63d49e996c3fb8936.png

 

6A47AA0F-7D7E-469E-9CA7-C5D121835A15.png.bb5140e7b1adc0e4846ef3988247631d.png
 

i kind of like the depiction here of how it plays out, so we’ll see. 

Hope this helps !

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6 hours ago, Allsnow said:

He's too busy fantasizing about next weekend's cool shot and low dewpoints. 🌭

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7 hours ago, Allsnow said:

Did it on Twitter. But basically Saturday night rain threat and that’s it after that. Euro was to amplified with shortwave out west which was causing front to hang up on east coast more. 

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Thanks for tips Irishbri; a little concerned about pre-frontal pop-up convection that is appearing on the NAM 3k but at this point, I can't change it, will just have to deal with it.  It would be nice to only have the later t-storms from the frontal passage because that might be after my athletic event is over (in Philadelphia at Franklin Field).  If anyone here has some hankering for pre-Olympic track and field, Ajee Wilson our hometown Olympian will be racing the 800m (https://www.instagram.com/p/CRW0c56jLGW/?utm_source=ig_web_copy_link ).  Admission is free.

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12 hours ago, irishbri74 said:

Welcome!! And great 1st post! I’m guessing you have some kind of 1st responded/military background due to your military clock usage?! Haha

 

-only use the HRRR inside of 6-8 hours. Beyond that, it’s prone to big swings. 
 

- NAM can get weird too outside of 48 hours. 3k NAM I use for about 36-48 hours out. I barely look at the RGEM . 
 

any higher resolution model tends to be fickle outside that 48 hour timeframe. Especially any CAM’s (Convection Allowing model, EG; 3k NAM, wrf etc). 
 

Gfs tends to be progressive/faster biased, while euro is slower. So most times, if there both doing there bias thing,a blend can work best for timing. 
 

Looking at Saturday: we’ll have a pretty humid, high cape environment. Not the best shear/flow, but we do have an approaching shortwave approaching from the west. Then we have to see about about a lee-side trough triggering storms early, as what usually happens in these uncapped, unstable environments. 
2D40D39A-5CE6-4B82-B884-627B65417A5D.png.fda697cf65c1eff1b72124e72e264bf9.png
 

-2500-3000jnCape

-Total totals around 48.. not bad, not great. 
 

- 25 knots effective shear. Not the best, but some deeper mid level shear could stop storms from collapsing in on themselves. (Organize a bit better)

In simpler terms? Looks like maybe a few different “rounds/opportunists” for storms to fire. Some pre-frontal stuff, which would use up the best thermodynamics, but missing the best lift. This would be scattered hit or miss stuff around in the afternoon- evening. 
 

And then the “main show”. With the approaching front later on in the evening (6-11). 385677AA-1B2C-469D-B38B-A6029B68FD8D.png.d6daf4e6e3b150c63d49e996c3fb8936.png

 

6A47AA0F-7D7E-469E-9CA7-C5D121835A15.png.bb5140e7b1adc0e4846ef3988247631d.png
 

i kind of like the depiction here of how it plays out, so we’ll see. 

Hope this helps !

nice write up Bri

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2 things I'm worried about for today. 

1. Being displaced further south from main dynamics with area of low pressure to our northeast. So main convection goes nw while we get a broken line of something.

2. Any prefrontal convection, in terms of reducing instability due to rains or anvil tops getting sheared out towards leaving us in cloudier regime right before main line comes in.

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3 hours ago, tombo82685 said:

2 things I'm worried about for today. 

1. Being displaced further south from main dynamics with area of low pressure to our northeast. So main convection goes nw while we get a broken line of something.

2. Any prefrontal convection, in terms of reducing instability due to rains or anvil tops getting sheared out towards leaving us in cloudier regime right before main line comes in.

Yeah definitely looks like the main show will be to our north

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30 minutes ago, Colin said:

Yeah definitely looks like the main show will be to our north

For heavy rain yes, svr probably not 

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On 7/16/2021 at 7:39 AM, irishbri74 said:

Welcome!! And great 1st post! I’m guessing you have some kind of 1st responded/military background due to your military clock usage?! Haha

 

-only use the HRRR inside of 6-8 hours. Beyond that, it’s prone to big swings. 
 

- NAM can get weird too outside of 48 hours. 3k NAM I use for about 36-48 hours out. I barely look at the RGEM . 
 

any higher resolution model tends to be fickle outside that 48 hour timeframe. Especially any CAM’s (Convection Allowing model, EG; 3k NAM, wrf etc). 
 

Gfs tends to be progressive/faster biased, while euro is slower. So most times, if there both doing there bias thing,a blend can work best for timing. 
 

Looking at Saturday: we’ll have a pretty humid, high cape environment. Not the best shear/flow, but we do have an approaching shortwave approaching from the west. Then we have to see about about a lee-side trough triggering storms early, as what usually happens in these uncapped, unstable environments. 
2D40D39A-5CE6-4B82-B884-627B65417A5D.png.fda697cf65c1eff1b72124e72e264bf9.png
 

-2500-3000jnCape

-Total totals around 48.. not bad, not great. 
 

- 25 knots effective shear. Not the best, but some deeper mid level shear could stop storms from collapsing in on themselves. (Organize a bit better)

In simpler terms? Looks like maybe a few different “rounds/opportunists” for storms to fire. Some pre-frontal stuff, which would use up the best thermodynamics, but missing the best lift. This would be scattered hit or miss stuff around in the afternoon- evening. 
 

And then the “main show”. With the approaching front later on in the evening (6-11). 385677AA-1B2C-469D-B38B-A6029B68FD8D.png.d6daf4e6e3b150c63d49e996c3fb8936.png

 

6A47AA0F-7D7E-469E-9CA7-C5D121835A15.png.bb5140e7b1adc0e4846ef3988247631d.png
 

i kind of like the depiction here of how it plays out, so we’ll see. 

Hope this helps !

You're in cold season form already! 

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Question for the professionals and those willing to take a shot at this question.

Given the smoke/haziness in the air, how much does that factor in to the SPC putting out a slight risk for severe storms?   Wouldn't a lot of that energy be "stolen" by the smoke/haze since it seems like temps are capped under that cover?

 

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I would imagine it cuts down on CAPE quite a bit, but SPC Mesoscale analysis is still predicting us to get to about 3k Surface CAPE and 1500-2k K/Kg MLCAPE which should be plenty to fire up the storms. This (anecdotally based on when I check in) is about 60-75% of our peak CAPE this time of year. It's not unusual to see us at 4.5k surface and over 3k ML on a hot high 80s day like today if it is clear.

I also wonder in cases like today how far out front the cold front pushes the smoke out of the way. Are we possibly looking at 1-2 hour window of significant clearing and heating ahead of the front? Visible sat this morning appears to have the smoke just sitting ahead of the front.

disclaimer: I'm by no means a professional :)

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1 hour ago, SalemCountyNJ said:

Southwest NJ - The 51st State  - Never the same weather as the rest of the State - LOL...

SW NJ has been merged into Delaware. Congrats. 

BF1F79B0-9141-4D57-8D51-DB60ED37C90F.png

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50 kts of shear is impressive and will pull me out of hibernation.  NWS mentions cloud debris from overnight MCS well to our west could muck up instability, but should those clouds shunt south, among other factors, we could be in store for an active severe weather day:

image.png.e9fccc4eaa2ae27eb337fde8a130b4b1.png

SPC
Concerning the severe potential, a 45 to 60 knot mid-level jet is
   forecast to move southeastward across the Great Lakes region. The
   exit region of this feature should move across the Mid Atlantic
   during the late afternoon and early evening. This will help to
   create strong deep-layer shear across much of the region. Forecast
   soundings at 00Z/Friday from central Ohio into south-central
   Pennsylvania have 0-6 km shear near 50 kt with some directional
   shear in the lowest 2 kilometers above ground level. 
   This should support severe storm development during the mid to late
   afternoon, with supercells possible. Supercells could have an
   isolated tornado threat, although this potential will depend upon
   storm mode. If linear mode ends up being dominant, then the
   wind-damage threat could be the greater of the two threats.

NWS

With those caveats mentioned, the dynamics on Thursday are no doubt
impressive, unlike any we`ve seen this year in terms of the
potential overlap of instability, shear, and forcing if everything
comes together right. 28.0z CAM guidance largely clobbers the region
with severe convection Thursday afternoon and evening, but run-to-
run consistency has been poor. Should several of those 0z CAM
solutions (i.e. 3km NAM, ARW) and their associated forecast
soundings come to pass, then a significant severe weather event with
all severe hazards would be likely. The Storm Prediction Center has
added a Slight Risk of severe weather over much of the region. Feel
that is very reasonable at this stage, and highly recommend
referencing the SWODY2 discussion for additional information. We
should stress again that confidence in the details of the Thursday
forecast is low, but encourage all users to monitor the forecast due
to both the uncertainty and the higher than normal potential threat
level if all factors were to come together.
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