Alert archive / Maryland / Mesoscale Discussions in 2021

Mesoscale Discussion 975

June 14, 20214 states

The Storm Prediction Center issued this mesoscale discussion at Jun 14, 2021, 10:09 PM EDT for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jun 14, 2021, 10:09 PM EDT (02:09 UTC)
Expired: Jun 15, 2021, 12:15 AM EDT
In force: 2 hr
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 273

All 34 counties

Kent County, DE, New Castle County, DE, Sussex County, DE, Anne Arundel County, MD, Calvert County, MD, Caroline County, MD, Charles County, MD, Dorchester County, MD, Kent 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, Burlington County, NJ, Camden County, NJ, Cape May County, NJ, Cumberland County, NJ, Gloucester County, NJ, Ocean County, NJ, Salem County, NJ, Arlington County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, City of Manassas, VA, City of Manassas Park, VA, Fairfax County, VA, Fauquier County, VA, Prince William County, VA, Stafford County, VA

The radar

The Dover AFB radar (KDOX), 34 km from the middle of the area, began a volume at 02:10 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

Wallops Is Stn, VA (KWAL), launched 00:00Z, 2.2 hours before the alert went out and 120 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 464 J/kg
Mixed-layer CIN: -64 J/kg
Mixed-layer LCL: 989 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 5 m²/s²
0-3 km storm-relative helicity: 38 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -0.0

Open this sounding in Storm Lab

The text

As transmitted.

868 
ACUS11 KWNS 150209
SWOMCD
SPC MCD 150209 
NJZ000-MDZ000-DEZ000-VAZ000-DCZ000-150415-

Mesoscale Discussion 0975
NWS Storm Prediction Center Norman OK
0909 PM CDT Mon Jun 14 2021

Areas affected...Northern Virginia...eastern Maryland...Delaware and
southern New Jersey

Concerning...Severe Thunderstorm Watch 273...

Valid 150209Z - 150415Z

The severe weather threat for Severe Thunderstorm Watch 273
continues.

SUMMARY...Thunderstorms will continue to pose a risk for damaging
winds into the late evening hours as a cold front continues to push
eastward.

DISCUSSION...Thunderstorm coverage has increased along an eastward
moving cold front over the past 1-2 hours across VA into central NJ.
A few instances of severe hail have been noted, but wind damage
reports have been more common with this activity. Overall,
instability and deep-layer shear remain favorable for organized
convection in the near-term as sampled by the 00Z IAD sounding.
Storm modes will likely continue to gradually grow upscale with
strong, more consolidated outflows possible, which will pose a risk
for damaging winds. Temperatures across the region have begun to
cool with the loss of daytime heating, which is slowly increasing
mixed-layer inhibition and reducing MLCAPE. However, cool
temperatures in the 700-500 mb layer and strong forcing along the
cold front should continue to support thunderstorms into the late
evening hours.

..Moore.. 06/15/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...PHI...AKQ...LWX...

LAT...LON   38827793 39267642 39717532 40167432 40117389 39687405
            39117460 38697484 38257516 37997543 38037626 38347699
            38487794 38827793

Nearby

Mesoscale Discussions in Maryland, 2021 Mesoscale Discussions in Virginia, 2021 Mesoscale Discussions in New Jersey, 2021 Every 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.