Alert archive / Maryland / Mesoscale Discussions in 2012
Mesoscale Discussion 1630
The Storm Prediction Center issued this mesoscale discussion at Jul 28, 2012, 12:26 PM EDT for 7 states. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 28, 2012, 12:26 PM EDT (16:26 UTC)
- Expired
- Jul 28, 2012, 2:30 PM EDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 60%
All 96 counties
Kent County, DE, New Castle County, DE, Sussex County, DE, Hampden County, MA, Hampshire County, MA, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Caroline County, MD, Carroll County, MD, Cecil County, MD, Charles County, MD, City of Baltimore, MD, Dorchester County, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Prince George's County, MD, Queen Anne's County, MD, Saint Mary's County, MD, Somerset County, MD, Talbot County, MD, Wicomico County, MD, Worcester County, MD, Atlantic County, NJ, Bergen County, NJ, Burlington County, NJ, Camden County, NJ, Cape May County, NJ, Cumberland County, NJ, Essex County, NJ, Gloucester County, NJ, Hudson County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Morris County, NJ, Ocean County, NJ, Passaic County, NJ, Salem County, NJ, Somerset County, NJ, Sussex County, NJ, Union County, NJ, Warren County, NJ, Bronx County, NY, Columbia County, NY, Dutchess County, NY, Kings County, NY, New York County, NY, Orange County, NY, Putnam County, NY, Queens County, NY, Richmond County, NY, Rockland County, NY, Sullivan County, NY, Ulster County, NY, Westchester County, NY, Adams County, PA, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Dauphin County, PA, Delaware County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Monroe County, PA, Montgomery County, PA, Northampton County, PA, Philadelphia County, PA, Pike County, PA, Schuylkill County, PA, York County, PA, Arlington County, VA, Caroline County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Manassas, VA, City of Manassas Park, VA, Culpeper County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, King George County, VA, Loudoun County, VA, Northumberland County, VA, Prince William County, VA, Richmond County, VA, Stafford County, VA, Westmoreland County, VA
The radar
The Philadelphia radar (KDIX), 43 km from the middle of the area, began a volume at 16:28 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 12:00Z, 4.4 hours before the alert went out and 200 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
- 424 J/kg
- Mixed-layer CIN
- -72 J/kg
- Mixed-layer LCL
- 705 m above ground
- 0-6 km bulk shear
- 44 kt
- 0-1 km storm-relative helicity
- 59 m²/s²
- 0-3 km storm-relative helicity
- 66 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.1
The text
As transmitted, in the capitals the NWS used until 2016.
655
ACUS11 KWNS 281627
SWOMCD
SPC MCD 281626
MAZ000-CTZ000-NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-DCZ000-281830-
MESOSCALE DISCUSSION 1630
NWS STORM PREDICTION CENTER NORMAN OK
1126 AM CDT SAT JUL 28 2012
AREAS AFFECTED...PORTIONS ERN PA...NRN/ERN VA...SWRN NEW
ENGLAND...DE...SERN NY...DC..NJ...MD EXCEPT PANHANDLE.
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 281626Z - 281830Z
PROBABILITY OF WATCH ISSUANCE...60 PERCENT
SUMMARY...CONVECTION FCST TO INCREASE CONSIDERABLY IN COVERAGE
ACROSS DISCUSSION AREA THROUGH MID-AFTN. MOST INTENSE CELLS WILL
PRODUCE DAMAGING GUSTS AND OCNL HAIL. SEVERAL MULTICELLULAR
CLUSTERS/BANDS WITH AGGREGATE COLD POOLS ALSO ARE
POSSIBLE...ENHANCING WIND-DAMAGE POTENTIAL ON MESO-BETA SCALE.
DISCUSSION...16Z SFC MESOANALYSIS SHOWED WAVY/QUASISTATIONARY FRONT
FROM OFFSHORE LONG ISLAND WWD THROUGH WEAK LOW JUST OFF NRN NJ
SHORE...THEN GENERALLY WWD OVER SRN PA AND SWWD FROM SWRN PA OVER OH
VALLEY. SFC TROUGHS EXTENDED NWD FROM LOW NEAR HUDSON VALLEY AND
SWWD FROM NRN NJ ACROSS CENTRAL CHESAPEAKE BAY TO S-CENTRAL VA AND
WEAK LOW OVER WRN NC. EACH OF THOSE MAY FOCUS CONVECTIVE THREAT.
RR MODEL REASONABLY INDICATES POTENTIAL FOR LOW TO FORM ALONG SRN
TROUGH OVER CENTRAL/NRN VA...AS MID-UPPER LEVEL PERTURBATION APCHS.
THIS WOULD FURTHER ENHANCE LOW-LEVEL CONVERGENCE/LIFT IN THAT
AREA...AS WILL SEA-BREEZE AND BAY-BREEZE BOUNDARIES NEAR COASTLINES.
AIR MASS ACROSS THIS REGION WILL CONTINUE FAVORABLE
DESTABILIZATION...WITH STG SFC DIABATIC HEATING WELL UNDERWAY AND
CINH NEARLY GONE OVER MOST OF AREA. INSOLATION AND PRESENCE OF RICH
BOUNDARY-LAYER MOISTURE...EVIDENT IN SFC DEW POINTS LOW-MID 70S F
AND 1.5-1.75 INCH GPS PW READINGS...WILL OFFSET WEAK LAPSE RATES
ALOFT ENOUGH TO YIELD MLCAPE 1000-1500 J/KG. VIS IMAGERY
ACCORDINGLY SHOWS DEEP CU...TCU AND CB IN PATCHES FROM SRN PA AND NJ
SWWD ACROSS CENTRAL/SRN MD AND ALSO DELMARVA PENINSULA...ON BOTH
SIDES OF CHESAPEAKE BAY AND INVOF TROUGH. SWLY EFFECTIVE SHEAR
VECTORS WITH 30-40 KT MAGNITUDES WILL AID IN MULTICELL
ORGANIZATION...AND TRANSIENT SUPERCELL STRUCTURES CANNOT BE RULED
OUT.
..EDWARDS/CORFIDI.. 07/28/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...BOX...OKX...ALY...PHI...BGM...AKQ...CTP...LWX...
LAT...LON 41207538 42327393 42397228 41387218 40727377 40147396
39467435 39027478 38817508 38417508 38047533 37787577
37727713 38597807 40347692 42117424 41207538SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 28, 1:36 PM EDT | Severe Thunderstorm Watch | SPC | Greater Bridgeport Planning Region, Naugatuck Valley Planning Region | 8 hr |
| Jul 28, 4:18 PM EDT | Mesoscale Discussion | SPC | 87 min | |
| Jul 27, 8:28 PM EDT | Mesoscale Discussion | SPC | Buchanan | 2 hr |
| Jul 28, 2:18 PM EDT | Mesoscale Discussion | SPC | Amelia, Brunswick, Charles City, Chesterfield, Dinwiddie, Greensville and 20 more | 117 min |
Nearby
Mesoscale Discussions in Maryland, 2012Mesoscale Discussions in New Jersey, 2012Mesoscale Discussions in Virginia, 2012Every mesoscale discussion in 2012
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.