Alert archive / New York / Mesoscale Discussions in 2021
Mesoscale Discussion 1364
The Storm Prediction Center issued this mesoscale discussion at Jul 27, 2021, 10:33 AM EDT for 15 counties in New York. It was in force for 117 min.
The area
The outline as issued.
The facts
- Issued
- Jul 27, 2021, 10:33 AM EDT (14:33 UTC)
- Expired
- Jul 27, 2021, 12:30 PM EDT
- In force
- 117 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
Counties Allegany County, NY, Cattaraugus County, NY, Cayuga County, NY, Erie County, NY, Genesee County, NY, Livingston County, NY, Monroe County, NY, Onondaga County, NY, Ontario County, NY, Schuyler County, NY, Seneca County, NY, Steuben County, NY, Wayne County, NY, Wyoming County, NY, Yates County, NY
The radar
The Buffalo radar (KBUF), 93 km from the middle of the area, began a volume at 14:36 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Buffalo Intl Airport, NY (KBUF), launched 12:00Z, 2.6 hours before the alert went out and 89 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
- 15 J/kg
- Mixed-layer CIN
- -173 J/kg
- Mixed-layer LCL
- 1473 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- 95 m²/s²
- 0-3 km storm-relative helicity
- 75 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
465
ACUS11 KWNS 271434
SWOMCD
SPC MCD 271433
NYZ000-271630-
Mesoscale Discussion 1364
NWS Storm Prediction Center Norman OK
0933 AM CDT Tue Jul 27 2021
Areas affected...Western NY
Concerning...Severe potential...Watch possible
Valid 271433Z - 271630Z
Probability of Watch Issuance...40 percent
SUMMARY...Thunderstorms are expected to develop across western NY
within the next hour or two. Some of these storms could become
strong enough to produce damaging wind gusts and trends are being
monitored for possible watch issuance.
DISCUSSION...Recent visible satellite and radar imagery reveals a
compact vorticity maximum/mesoscale convective vortex moving from
southern Lake Huron into southwestern Ontario. Some deeper
convection has been noted just ahead of this vorticity max across
central portions of southwestern Ontario, likely associated with the
stronger ascent attendant to the MCV. Based on current motion, this
area of stronger ascent should reach BUF vicinity around 16Z before
then continuing downstream across western NY.
The air mass preceding this vorticity maximum is under full sun,
with temperatures likely reaching the low 80s within the next two
hours. Dewpoints are currently in the low 60s, but some mixing is
anticipated under the strong diurnal heating, likely dropping
dewpoints in the mid to upper 50s (perhaps even lower with eastern
extent) as the forcing for ascent arrives. As such, updraft strength
may be somewhat tempered by modest buoyancy. Nevertheless, enhanced
unidirectional westerly flow could still result in some stronger
downbursts capable of damage. Trends are being monitored for
possible watch issuance.
..Mosier/Hart.. 07/27/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BGM...BUF...
LAT...LON 42307905 42477924 42847894 43227900 43347856 43257722
43387663 43437638 43387604 43217585 42837598 42637621
42287680 42107747 42137837 42207878 42307905SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 27, 11:12 AM EDT | Severe Thunderstorm Watch | SPC | Allegany, Broome, Cattaraugus, Cayuga, Chautauqua, Chemung and 23 more | 7 hr |
| Jul 27, 2:01 PM EDT | Mesoscale Discussion | SPC | Albany, Allegany, Broome, Cattaraugus, Cayuga, Chemung and 29 more | 89 min |
| Jul 27, 2:47 PM EDT | Severe Thunderstorm Watch | SPC | Albany, Columbia, Dutchess, Fulton, Greene, Hamilton and 10 more | 6 hr |
| Jul 27, 4:36 PM EDT | Mesoscale Discussion | SPC | Albany, Bronx, Columbia, Delaware, Dutchess, Greene and 12 more | 84 min |
| Jul 27, 6:09 PM EDT | Mesoscale Discussion | SPC | Albany, Bronx, Broome, Columbia, Delaware, Dutchess and 10 more | 96 min |
Nearby
Mesoscale Discussions in New York, 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.