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2021 General Thunderstorm Discussion


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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

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Big fan of this update. I had never understood before why a run-of-the-mill summer thunderstorm was lumped into the same batch as a derecho, just in terms of warnings. The cell phone pings will clearly get the point across that it's a serious matter 👍

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6 hours ago, greg ralls said:

Looks like we're close to Marginal Risk tomorrow. Perhaps some storms to track.

image.png.b182df41982b4765d222cf8bf9115de2.png

From the Ohio Valley into the Mid-Atlantic area and vicinity, the
   pre-frontal airmass will be characterized by weak CAPE.  But, with
   strong/west-southwesterly flow aloft -- particularly across the
   upper Ohio Valley/central Appalachians region -- locally damaging
   wind gusts will be possible, particularly with any convective
   bands/line segments.  
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Strong language on tomorrow's wind threat, High Wind Watch in place region wide:

West to northwesterly winds will increase substantially as the day
progresses, especially into the evening hours, as the aforementioned
mid-level height falls and cold advection will support efficient
mixing to the 850-900 mb levels through at least the early evening.
Additionally, the vorticity maxima will cause tropopause folding
down to around the 500 mb level, which is often indicative of very
steep lapse rates. These factors are expected to preclude any
question regarding the unfavorable timing of maximum wind fields
during the evening hours (less of the typical diurnal mixing). Just
about all of the 00Z guidance suite indicate winds speeds in these
levels during this time increasing to 40-50+ kts, which are likely
to mix to the ground in the form of frequent wind gusts. Expect
sustained winds of 20-25 mph with gusts of 30-40 mph by the
afternoon hours, with gusts increasing to the 45-55+ mph range
during the evening hours. Sustained winds are forecast to peak in
the 30-35 mph range near the coasts and in the higher terrain north
and west.

At this juncture, Wind Advisory criteria wind gusts (45 mph or
greater) appear likely, especially from around 2 PM Friday through
around 2 AM Saturday across most of the area. We`ve issued a High
Wind Watch for this period given the potential for wind gusts of 55-
60 mph for a few hours, mainly during the evening (7 PM through
midnight). Additionally, potential exists for greater impacts than a
typical solid Wind Advisory event owing to the green up and foliage
on most trees in the area. Falling trees or tree limbs may bring
down power lines, potentially resulting in scattered power outages.
This will be a very long duration (~12 hr) high wind event, with
potentially significant impacts to the area.
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  • 4 weeks later...

Marginal risk for Wednesday. Wouldn't shock me if west of town gets pushed to slgt with earlier arrival out there. Instability numbers are decent, but timing and looks to be a bit of a cap could limit in my eyes

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SPC upgraded to slight, except for shore - 15% hail and wind

Farther south, surface temperatures
   should warm into the upper 80s across the Delmarva region and this
   higher buoyancy may result in a greater risk of hail from eastern PA
   into northern VA as thunderstorms develop a bit later during the mid
   afternoon.
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In my area the clouds only started clearing out within the past hour or so but there's still quite a few around. I'm not well versed on thunderstorm dynamics, but I would think that lessens the chance due to less warming, or am I wrong?

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10 minutes ago, mweav067 said:

In my area the clouds only started clearing out within the past hour or so but there's still quite a few around. I'm not well versed on thunderstorm dynamics, but I would think that lessens the chance due to less warming, or am I wrong?

I was thinking the same thing earlier this morning, but the clouds are clearing quickly

CODNEXLAB-GOES-East-regional-northeast-02-15_31Z-20210526_map_-10-1n-10-100.gif

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3 hours ago, Chubbs said:

SPC upgraded to slight, except for shore - 15% hail and wind


Farther south, surface temperatures
   should warm into the upper 80s across the Delmarva region and this
   higher buoyancy may result in a greater risk of hail from eastern PA
   into northern VA as thunderstorms develop a bit later during the mid
   afternoon.

They dropped the hail to 5% in the 9am update fwiw. Less impressed with the discrete cells potential since last night in guessing.

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slgt risk out Thursday. Besides heavy rain threat there is bit of a dry layer punch aloft to support some damaging winds. Also a bit of shear too, for isolated nado risk. Would feel better though if we saw instability parameters increase a bit more

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On 6/1/2021 at 11:32 AM, tombo82685 said:

slgt risk out Thursday. Besides heavy rain threat there is bit of a dry layer punch aloft to support some damaging winds. Also a bit of shear too, for isolated nado risk. Would feel better though if we saw instability parameters increase a bit more

Mesos are pretty bullish on the instability being there. Skew-t sounding looks pretty solid atleast out in western burbs for some damaging winds. Note the dry punch aloft in the skew t just above our heads. Much easier to transport winds with dry air in profile than with a saturated profile. 

nam4km_2021060218_027_40.28--75.52.png

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With the second round of storms in the afternoon and evening, there remains a risk for heavy rain (precipitable water values remain above normal, though storm motions should be slightly faster), but there also could be a risk for severe storms. There remains a slight risk over portions of our region (generally along and west of the 95 corridor) due to 35 to 40 kt of bulk shear and potential for SB CAPE values near 1000 J/kg (though as mentioned above this is uncertain given the characteristics of the lull). The primary concern is the potential for wet microbursts resulting in damaging winds.
 

thoughts from Mt. Holly ^^

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Lets see how the mesos do. Most say a round of action between 4am-9am. Then a break followed by more activity from about 4pm-midnight moving west to east across the area.

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6 hours ago, Parsley said:

Lets see how the mesos do. Most say a round of action between 4am-9am. Then a break followed by more activity from about 4pm-midnight moving west to east across the area.

They were pretty robust for this mornings round of storms, however, I'm not seeing that really pan out, other than further South.  Let's see what the afternoon/evening round brings.

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Tue-thurs, maybe friday has a heavy rain look to it again. High PWATS approaching and exceeding 2". Very weak and little veering of the winds aloft is a recipe for slow moving storms

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