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Mt. Holly Severe Threats


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18z Nam looks like it is coming in with the early AM convection like the GFS had last night. Maybe an early day mcs or something before the afternoon fireworks provided by mother nature?

NAM's been hinting at it for a day or so.

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Sorry to be a Debby Downer, but I'm not that excited about Wednesday. Looking at the 0z NAM for KPHL, You have weak mid level lapse rates (850-500 mb lapse rates of 6.4 C/km...which is okay, but if you really want hail, you're looking for a 7), very little vertical shear (0-6 km shear speed maxes at 21.5 kts at 21z...given somewhat of a turning from W at the surface to NW at 500 mb, your 0-6 km shear vector *might* approach 30 kts, but probably will be below 25 kts. ouch.), and no help from LCLs, which are in the 1200-1800 m range between 18z and 0z.

You also have morning convection potentially screwing things up.

What you DO have is high CAPE values of around 3000 J/kg, and PWATs of 1.5-1.8 inches, which given slow steering flow and associated splitting storms, flash flooding may be a threat.

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Sorry to be a Debby Downer, but I'm not that excited about Wednesday. Looking at the 0z NAM for KPHL, You have weak mid level lapse rates (850-500 mb lapse rates of 6.4 C/km...which is okay, but if you really want hail, you're looking for a 7), very little vertical shear (0-6 km shear speed maxes at 21.5 kts at 21z...given somewhat of a turning from W at the surface to NW at 500 mb, your 0-6 km shear vector *might* approach 30 kts, but probably will be below 25 kts. ouch.), and no help from LCLs, which are in the 1200-1800 m range between 18z and 0z.

You also have morning convection potentially screwing things up.

What you DO have is high CAPE values of around 3000 J/kg, and PWATs of 1.5-1.8 inches, which given slow steering flow and associated splitting storms, flash flooding may be a threat.

you are the yang to stormspotterlive's yin

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Sorry to be a Debby Downer, but I'm not that excited about Wednesday. Looking at the 0z NAM for KPHL, You have weak mid level lapse rates (850-500 mb lapse rates of 6.4 C/km...which is okay, but if you really want hail, you're looking for a 7), very little vertical shear (0-6 km shear speed maxes at 21.5 kts at 21z...given somewhat of a turning from W at the surface to NW at 500 mb, your 0-6 km shear vector *might* approach 30 kts, but probably will be below 25 kts. ouch.), and no help from LCLs, which are in the 1200-1800 m range between 18z and 0z.

You also have morning convection potentially screwing things up.

What you DO have is high CAPE values of around 3000 J/kg, and PWATs of 1.5-1.8 inches, which given slow steering flow and associated splitting storms, flash flooding may be a threat.

Tomorrow's morning convection is currently exiting Michigan. Let's see what the day brings.

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Sorry to be a Debby Downer, but I'm not that excited about Wednesday. Looking at the 0z NAM for KPHL, You have weak mid level lapse rates (850-500 mb lapse rates of 6.4 C/km...which is okay, but if you really want hail, you're looking for a 7), very little vertical shear (0-6 km shear speed maxes at 21.5 kts at 21z...given somewhat of a turning from W at the surface to NW at 500 mb, your 0-6 km shear vector *might* approach 30 kts, but probably will be below 25 kts. ouch.), and no help from LCLs, which are in the 1200-1800 m range between 18z and 0z.

You also have morning convection potentially screwing things up.

What you DO have is high CAPE values of around 3000 J/kg, and PWATs of 1.5-1.8 inches, which given slow steering flow and associated splitting storms, flash flooding may be a threat.

yea i agree, their will be storms but i don't see severe. I see more hvy rain threat than anything.

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they took awy the slgt risk tomorrow for the northeast... makes sense i think the early morning stuff will probably muck thing up a bit,

if it comes through tonight (which it may given the pace it's going) they may be bumping back up to slight tomorrow.

These storms have been outrunning modeling so far...may very well be through the region before daybreak tomorrow.

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RPM has storms tonight moving through between midnight and 6am then it clears out with sun by morning. Would suspect unless we get good elevated instability to move in they would be weaker in our area like it shows. as for Tomorrow I agree with the general see text maybe an isolated severe storm at best now but as other have mentioned the set up is not as great and heavy rain fall really does look like a bigger threat now.

http://www.chicagowe...r.com/maps/rpm/

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RPM has storms tonight moving through between midnight and 6am then it clears out with sun by morning. Would suspect unless we get good elevated instability to move in they would be weaker in our area like it shows. as for Tomorrow I agree with the general see text maybe an isolated severe storm at best now but as other have mentioned the set up is not as great and heavy rain fall really does look like a bigger threat now.

http://www.chicagowe...r.com/maps/rpm/

Hmm. That shows the current MCS dies about where it is and then a new complex forms after dark, maybe along the outflow boundary and it looks pretty nasty until it gets to Lancaster where it starts to fizzle. I'm not saying that can't happen, but I wouldn't call that a high confidence forecast. I've never look at it systematically, but my gut says the models are pretty horrible with derecho's for whatever reason.

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Hmm. That shows the current MCS dies about where it is and then a new complex forms after dark, maybe along the outflow boundary and it looks pretty nasty until it gets to Lancaster where it starts to fizzle. I'm not saying that can't happen, but I wouldn't call that a high confidence forecast. I've never look at it systematically, but my gut says the models are pretty horrible with derecho's for whatever reason.

Cell NE of PIT has 1.25" hail per doppler...wouldn't shock me if it makes it pretty close to us later on.

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