Alert archive / New Jersey / Mesoscale Discussions in 2017
Mesoscale Discussion 628
The Storm Prediction Center issued this mesoscale discussion at May 1, 2017, 7:16 PM EDT for 15 counties in New Jersey; 4 counties in New York; 6 counties in Pennsylvania. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- May 1, 2017, 7:16 PM EDT (23:16 UTC)
- Expired
- May 1, 2017, 9:45 PM EDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 20%
All 25 counties
Bergen County, NJ, Burlington County, NJ, Camden County, NJ, Essex County, NJ, Gloucester County, NJ, Hudson County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Morris County, NJ, Passaic County, NJ, Salem County, NJ, Somerset County, NJ, Union County, NJ, Warren County, NJ, New York County, NY, Richmond County, NY, Rockland County, NY, Westchester County, NY, Bucks County, PA, Chester County, PA, Delaware County, PA, Montgomery County, PA, Northampton County, PA, Philadelphia County, PA
The radar
The Philadelphia radar (KDIX), 68 km from the middle of the area, began a volume at 23:17 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
Brookhaven, NY (KOKX), launched 12:00Z, 11.3 hours before the alert went out and 186 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 497 m above ground
- 0-6 km bulk shear
- 48 kt
- 0-1 km storm-relative helicity
- 260 m²/s²
- 0-3 km storm-relative helicity
- 256 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
558
ACUS11 KWNS 012317
SWOMCD
SPC MCD 012316
NYZ000-NJZ000-PAZ000-DEZ000-020145-
Mesoscale Discussion 0628
NWS Storm Prediction Center Norman OK
0616 PM CDT Mon May 01 2017
Areas affected...Portions of southeastern NY...NJ...extreme eastern
PA...extreme northern DE
Concerning...Severe potential...Watch unlikely
Valid 012316Z - 020145Z
Probability of Watch Issuance...20 percent
SUMMARY...Convection moving across northern parts of the
mid-Atlantic and vicinity later this evening may produce locally
strong wind gusts. Watch issuance is unlikely.
DISCUSSION...The leading convective line of an MCS from central NY
to central PA is advancing generally eastward around 25 kt, with
embedded bowing segments advancing northeastward around 45-50 kt.
Present indications are that the southern part of this activity will
enter the discussion area around/after 02-03Z.
Stronger midlevel height falls/deep ascent accompanying a speed
maximum will advance from northern PA through central/northern NY
and vicinity. This is where the most consolidated, sustained bowing
segments will likely track (north of the area). Nevertheless,
sufficient low-level moistening and related MLCAPE around 500-750
J/kg, amid 50-60 kt of effective shear, could support a few
persistent updrafts along the southern flank of the larger MCS
crossing the area later this evening. Also, a few cells crossing the
VA Piedmont in a warm-advection plume may also be weakening as they
move into the discussion area later this evening. Given the
relatively limited large-scale ascent, and eventual nocturnal gains
in boundary-layer static stability, the severe risk -- though
non-zero -- should be waning as storms potentially move across the
region later this evening.
..Cohen/Thompson.. 05/01/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OKX...PHI...
LAT...LON 40427572 40827526 41347410 41157370 39817442 39397506
39717577 40427572SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 1, 1:41 PM EDT | Mesoscale Discussion | SPC | Allegany, Cattaraugus, Genesee, Livingston, Ontario, Steuben and 2 more | 64 min |
| May 1, 2:12 PM EDT | Tornado Watch | SPC | Allegany, Broome, Cattaraugus, Cayuga, Chautauqua, Chemung and 23 more | 8 hr |
| May 1, 4:36 PM EDT | Mesoscale Discussion | SPC | Broome, Cayuga, Chemung, Chenango, Cortland, Madison and 11 more | 84 min |
| May 1, 6:29 PM EDT | Mesoscale Discussion | SPC | Albany, Chenango, Clinton, Columbia, Delaware, Dutchess and 20 more | 61 min |
| May 1, 6:52 PM EDT | Severe Thunderstorm Watch | SPC | Albany, Columbia, Delaware, Dutchess, Essex, Franklin and 15 more | 4 hr |
| May 1, 11:59 AM EDT | Mesoscale Discussion | SPC | Allegheny, Armstrong, Beaver, Butler, Clarion, Fayette and 8 more | 2 hr |
| May 1, 12:32 PM EDT | Tornado Watch | SPC | Allegheny, Armstrong, Beaver, Butler, Clarion, Crawford and 11 more | 4 hr |
| May 1, 5:54 PM EDT | Severe Thunderstorm Watch | SPC | Adams, Cumberland, Dauphin, Franklin, Lancaster, Lebanon and 3 more | 5 hr |
Nearby
Mesoscale Discussions in New Jersey, 2017Mesoscale Discussions in Pennsylvania, 2017Mesoscale Discussions in New York, 2017Every mesoscale discussion in 2017
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.