Alert archive / New York / Mesoscale Discussions in 2011
Mesoscale Discussion 658
The Storm Prediction Center issued this mesoscale discussion at Apr 28, 2011, 6:21 AM EDT for 4 states. It was in force for 54 min.
The area
The outline as issued.
The facts
- Issued
- Apr 28, 2011, 6:21 AM EDT (10:21 UTC)
- Expired
- Apr 28, 2011, 7:15 AM EDT
- In force
- 54 min
- Issued by
- the Storm Prediction Center
All 49 counties
Kent County, DE, New Castle County, DE, Bergen County, NJ, Burlington County, NJ, Camden County, NJ, Cumberland County, NJ, Gloucester County, NJ, Hunterdon County, NJ, Mercer County, NJ, Morris County, NJ, Passaic County, NJ, Salem County, NJ, Somerset County, NJ, Sussex County, NJ, Warren County, NJ, Albany County, NY, Chenango County, NY, Columbia County, NY, Delaware County, NY, Dutchess County, NY, Fulton County, NY, Greene County, NY, Montgomery County, NY, Orange County, NY, Otsego County, NY, Putnam County, NY, Rensselaer County, NY, Rockland County, NY, Saratoga County, NY, Schenectady County, NY, Schoharie County, NY, Sullivan County, NY, Ulster County, NY, Warren County, NY, Washington County, NY, Westchester County, NY, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Delaware County, PA, Lackawanna County, PA, Lehigh County, PA, Monroe County, PA, Montgomery County, PA, Northampton County, PA, Philadelphia County, PA, Pike County, PA, Wayne County, PA
The radar
The Philadelphia radar (KDIX), 116 km from the middle of the area, began a volume at 10:22 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
Brookhaven, NY (KOKX), launched 00:00Z, 10.4 hours before the alert went out and 175 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
- 172 J/kg
- Mixed-layer CIN
- -34 J/kg
- Mixed-layer LCL
- 447 m above ground
- 0-6 km bulk shear
- 32 kt
- 0-1 km storm-relative helicity
- 207 m²/s²
- 0-3 km storm-relative helicity
- 246 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
448
ACUS11 KWNS 281022
SWOMCD
SPC MCD 281021
NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-281115-
MESOSCALE DISCUSSION 0658
NWS STORM PREDICTION CENTER NORMAN OK
0521 AM CDT THU APR 28 2011
AREAS AFFECTED...ERN NY...ERN PA...WRN NJ...DE...EXTREME ERN MD
CONCERNING...SEVERE THUNDERSTORM WATCH 249...
VALID 281021Z - 281115Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 249
CONTINUES.
A NEARLY SOLID QLCS WILL CONTINUE MOVING NEWD AT 40 TO 50 KT ACROSS
PORTIONS OF ERN NY AND NERN PA...AND MOVE INTO THE HUDSON VALLEY AND
ALBANY AREA DURING THE NEXT HALF HOUR TO HOUR. MARGINAL INSTABILITY
PRECEDING THE QLCS WILL ALLOW IT TO BE MAINTAINED AS IT CONTINUES
TRACKING NORTHEAST...GIVEN EFFECTIVE BULK SHEAR MAGNITUDES AROUND 60
KT. AS SUCH...THE WW MAY NEED TO BE EXTENDED EWD TO THE NEW YORK
BORDER. THE PRIMARY THREAT WILL CONTINUE TO BE DMGG WINDS...GIVEN
SSWLY WINDS OF 40-50 KT AROUND 1 KM AGL PER ALBANY VWP.
HOWEVER...WITH 0-1-KM STORM-RELATIVE HELICITY VALUES DERIVED FROM
THE VWP OF 313 M2/S2 SUGGESTING STRONG LOW-LEVEL VERTICAL WIND
SHEAR...THE THREAT FOR ONE OR TWO TORNADOES ASSOCIATED WITH EMBEDDED
MESOVORTEX WILL BE PRESENT. AS THE ACTIVITY SHIFTS FARTHER EAST INTO
NEW ENGLAND...IT WILL ENCOUNTER GROWING CINH AMIDST THE MORE STABLE
MARINE LAYER...TEMPERING THE OVERALL SVR THREAT. MEANWHILE...
SCATTERED CONVECTION FARTHER SOUTH OF THE QLCS ACROSS WW249 WILL
CONTINUE MOVING NEWD...AS WELL...POSING A THREAT FOR DMGG WINDS.
HOWEVER...THE LACK OF MORE ORGANIZED CONVECTIVE STRUCTURES COULD
MITIGATE THE POTENTIAL TO SOME DEGREE.
..COHEN.. 04/28/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...OKX...ALY...PHI...BGM...CTP...
LAT...LON 38817499 38857580 39237590 39687571 40197642 41227595
42867554 43697415 43467336 43017341 41147374 40837427
38817499SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 27, 8:15 PM EDT | Severe Thunderstorm Watch | SPC | Kent, New Castle, Sussex | 8 hr |
| Apr 28, 4:05 AM EDT | Severe Thunderstorm Watch | SPC | Kent, New Castle, Sussex | 6 hr |
| Apr 28, 9:45 AM EDT | Severe Thunderstorm Watch | SPC | Kent, New Castle, Sussex | 6 hr |
| Apr 28, 10:44 AM EDT | Mesoscale Discussion | SPC | Kent, New Castle | 61 min |
| Apr 28, 11:49 AM EDT | Mesoscale Discussion | SPC | Kent, New Castle | 56 min |
| Apr 28, 2:00 PM EDT | Mesoscale Discussion | SPC | Kent, Sussex | 60 min |
| Apr 28, 3:32 AM EDT | Mesoscale Discussion | SPC | Hunterdon, Sussex, Warren | 28 min |
| Apr 27, 9:03 PM EDT | Mesoscale Discussion | SPC | Cayuga, Chemung, Tioga, Tompkins | 57 min |
| Apr 27, 10:45 PM EDT | Mesoscale Discussion | SPC | Albany, Broome, Chenango, Delaware, Essex, Franklin and 15 more | 60 min |
| Apr 28, 2:20 AM EDT | Mesoscale Discussion | SPC | Broome, Chemung, Chenango, Cortland, Delaware, Fulton and 13 more | 55 min |
| Apr 27, 11:50 PM EDT | Severe Thunderstorm Watch | SPC | Adams, Bedford, Blair, Cambria, Cameron, Centre and 26 more | 7 hr |
Nearby
Mesoscale Discussions in New York, 2011Mesoscale Discussions in New Jersey, 2011Mesoscale Discussions in Pennsylvania, 2011Every mesoscale discussion in 2011
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.