Alert archive / New Jersey / Mesoscale Discussions in 2021

Mesoscale Discussion 1208

July 8, 20215 states

The Storm Prediction Center issued this mesoscale discussion at Jul 8, 2021, 10:01 PM EDT for 5 states. It was in force for 59 min.

The area

The outline as issued.

The facts

Issued
Jul 8, 2021, 10:01 PM EDT (02:01 UTC)
Expired
Jul 8, 2021, 11:00 PM EDT
In force
59 min
Issued by
the Storm Prediction Center
Concerning
Tornado watch 350

Counties Sussex County, DE, Somerset County, MD, Wicomico County, MD, Worcester County, MD, Atlantic County, NJ, Burlington County, NJ, Cape May County, NJ, Cumberland County, NJ, Monmouth County, NJ, Ocean County, NJ, Bronx County, NY, Kings County, NY, Nassau County, NY, New York County, NY, Queens County, NY, Richmond County, NY, Accomack County, VA, Northampton County, VA

The radar

The Dover AFB radar (KDOX), 69 km from the middle of the area, began a volume at 02:05 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Wallops Is Stn, VA (KWAL), launched 00:00Z, 2.0 hours before the alert went out and 141 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Wallops Is Stn, VA at 00:00Z on 2021-07-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 440 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Wallops Is Stn, VA at 00:00Z on 2021-07-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 151 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
440 J/kg
Mixed-layer CIN
-10 J/kg
Mixed-layer LCL
675 m above ground
0-6 km bulk shear
42 kt
0-1 km storm-relative helicity
151 m²/s²
0-3 km storm-relative helicity
336 m²/s²
Significant tornado parameter
0.3
Supercell composite
3.3

Open this sounding in Storm Lab

The text

As transmitted.

394 
ACUS11 KWNS 090201
SWOMCD
SPC MCD 090201 
NYZ000-CTZ000-NJZ000-MDZ000-DEZ000-VAZ000-090300-

Mesoscale Discussion 1208
NWS Storm Prediction Center Norman OK
0901 PM CDT Thu Jul 08 2021

Areas affected...Chesapeake Bay Vicinity

Concerning...Tornado Watch 350...

Valid 090201Z - 090300Z

The severe weather threat for Tornado Watch 350 continues.

SUMMARY...A marginal threat for a brief tornado may continue along
the immediate Atlantic coast beyond the expiration of Tornado Watch
350. No additional WW is expected this evening.

DISCUSSION...The strongest convection in WW 350 has continued to
move offshore in eastern North Carolina and Virginia. Farther
inland, there has been little notable low-level rotation on regional
radar imagery. As tropical storm Elsa continues northeast this
evening, an isolated stronger convective cell could develop along
the gulf stream and move inland. While low-level winds could still
support a brief tornado, the unfavorable low-level thermodynamic
environment -- especially inland of the immediate coast -- suggests
that this threat will be marginal. No additional watches are
anticipated this evening.

..Wendt.. 07/09/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...OKX...PHI...AKQ...

LAT...LON   37087614 38617580 40197467 40877389 41247319 40957274
            39887375 37807523 37107561 37087614

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 9, 2:15 PM EDTMesoscale DiscussionSPCKent, New Castle, Sussex2 hr
Jul 9, 4:35 PM EDTMesoscale DiscussionSPCNew Castle115 min
Jul 9, 3:28 AM EDTMesoscale DiscussionSPCAtlantic, Monmouth, Ocean2 hr

Nearby

Mesoscale Discussions in New Jersey, 2021Mesoscale Discussions in New York, 2021Mesoscale Discussions in Maryland, 2021Every mesoscale discussion in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.