Alert archive / New York / Mesoscale Discussions in 2021
Mesoscale Discussion 1736
The Storm Prediction Center issued this mesoscale discussion at Sep 13, 2021, 12:26 AM EDT for 15 counties in New York; Susquehanna County, Pennsylvania. It was in force for 94 min.
The area
The outline as issued.
The facts
- Issued
- Sep 13, 2021, 12:26 AM EDT (04:26 UTC)
- Expired
- Sep 13, 2021, 2:00 AM EDT
- In force
- 94 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 495
Counties Allegany County, NY, Broome County, NY, Chemung County, NY, Chenango County, NY, Cortland County, NY, Delaware County, NY, Livingston County, NY, Ontario County, NY, Otsego County, NY, Schuyler County, NY, Seneca County, NY, Steuben County, NY, Tioga County, NY, Tompkins County, NY, Yates County, NY, Susquehanna County, PA
The radar
The Binghamton radar (KBGM), 73 km from the middle of the area, began a volume at 04:27 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
Buffalo Intl Airport, NY (KBUF), launched 00:00Z, 4.4 hours before the alert went out and 165 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
- 412 J/kg
- Mixed-layer CIN
- -125 J/kg
- Mixed-layer LCL
- 706 m above ground
- 0-6 km bulk shear
- 50 kt
- 0-1 km storm-relative helicity
- 205 m²/s²
- 0-3 km storm-relative helicity
- 168 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 1.5
The text
As transmitted.
554
ACUS11 KWNS 130427
SWOMCD
SPC MCD 130426
NYZ000-PAZ000-130600-
Mesoscale Discussion 1736
NWS Storm Prediction Center Norman OK
1126 PM CDT Sun Sep 12 2021
Areas affected...Parts of western/southern New York State and
adjacent northern Pennsylvania
Concerning...Severe Thunderstorm Watch 495...
Valid 130426Z - 130600Z
The severe weather threat for Severe Thunderstorm Watch 495
continues.
SUMMARY...Occasional strong surface gusts (capable of producing
mainly tree damage) may continue to accompany an organized, but
weakening cluster of storms across the southern tier of New York
into the Catskills vicinity through 2-3 AM EDT. It is not clear
that another watch is needed, but trends will continue to be
monitored for this possibility.
DISCUSSION...Strongest recorded surface gusts with the long-lived
organized convective system have been around 40-45 kt, from near the
London, ON vicinity into the eastern shores of Lake Erie, around
Dunkirk, NY. However, fairly intense peak lightning flash rates
have begun to decrease substantially and the convective system
appears to be in the process of weakening. Still, an organized
structure remains, and activity is rapidly propagating eastward (in
excess of 50 kt), within a strong, convectively augmented westerly
mean wind field. At its current pace, it may reach the westerly
slopes of the Catskills by around 07Z. Even though convection
probably will continue to weaken, stronger ambient westerly
low-level wind fields (including 30-40 kt around 850 mb) across the
southern tier of New York may continue to contribute to potential
for occasional strong surface gusts which could approach severe
limits.
..Kerr.. 09/13/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...ALY...BGM...BUF...CTP...
LAT...LON 42867801 42897633 42787520 42317444 41777521 41847626
41887810 41837873 42237829 42867801SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 12, 9:14 PM EDT | Mesoscale Discussion | SPC | Erie | 91 min |
| Sep 12, 10:25 PM EDT | Severe Thunderstorm Watch | SPC | Allegany, Cattaraugus, Chautauqua, Chemung, Erie, Genesee and 7 more | 4 hr |
| Sep 13, 4:11 PM EDT | Mesoscale Discussion | SPC | Allegany, Cattaraugus, Chautauqua | 2 hr |
| Sep 13, 5:53 PM EDT | Severe Thunderstorm Watch | SPC | Cameron, Centre, Clarion, Clearfield, Clinton, Columbia and 14 more | 3 hr |
| Sep 13, 7:07 PM EDT | Mesoscale Discussion | SPC | Carbon, Centre, Clearfield, Columbia, Jefferson, Luzerne and 5 more | 113 min |
| Sep 13, 7:44 PM EDT | Severe Thunderstorm Watch | SPC | Bucks, Carbon, Lehigh, Luzerne, Monroe, Northampton | 4 hr |
Nearby
Mesoscale Discussions in New York, 2021Mesoscale Discussions in Pennsylvania, 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.