Alert archive / Virginia / Mesoscale Discussions in 2016

Mesoscale Discussion 102

February 15, 20166 states

The Storm Prediction Center issued this mesoscale discussion at Feb 15, 2016, 1:46 PM EST for 6 states. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Feb 15, 2016, 1:46 PM EST (18:46 UTC)
Expired: Feb 15, 2016, 6:45 PM EST
In force: 5 hr
Issued by: the Storm Prediction Center

All 109 counties

Kent County, DE, New Castle County, DE, 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, Talbot County, MD, Camden County, NJ, Cumberland County, NJ, Essex County, NJ, Gloucester County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Morris County, NJ, Salem County, NJ, Somerset County, NJ, Union County, NJ, Warren County, NJ, Adams County, PA, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester 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, York County, PA, Albemarle County, VA, Alleghany County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Arlington County, VA, Augusta County, VA, Bath County, VA, Bedford County, VA, Botetourt County, VA, Buckingham County, VA, Caroline County, VA, Chesterfield County, VA, City of Alexandria, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Covington, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Harrisonburg, VA, City of Lexington, VA, City of Lynchburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Richmond, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Craig County, VA, Culpeper County, VA, Cumberland County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Frederick County, VA, Goochland County, VA, Greene County, VA, Hanover County, VA, Highland County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Loudoun County, VA, Louisa County, VA, Madison County, VA, Nelson County, VA, Orange County, VA, Page County, VA, Powhatan County, VA, Prince William County, VA, Rappahannock County, VA, Richmond County, VA, Rockbridge County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Westmoreland County, VA, Jefferson County, WV

The radar

The Sterling radar (KLWX), 31 km from the middle of the area, began a volume at 18:45 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

Washington/Dulle, VA (KIAD), launched 12:00Z, 6.8 hours before the alert went out and 25 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 704 m above ground
0-6 km bulk shear: 74 kt
0-1 km storm-relative helicity: 264 m²/s²
0-3 km storm-relative helicity: 340 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

165 
ACUS11 KWNS 151846
SWOMCD
SPC MCD 151846 
NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-DCZ000-WVZ000-152345-

MESOSCALE DISCUSSION 0102
NWS STORM PREDICTION CENTER NORMAN OK
1246 PM CST MON FEB 15 2016

AREAS AFFECTED...PORTIONS OF THE MID-ATLANTIC

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 151846Z - 152345Z

SUMMARY...WINTER MIXED PRECIPITATION WILL CONTINUE TO ADVANCE
NORTHWARD ACROSS THE MID-ATLANTIC REGION. A TRANSITION FROM SNOW TO
A PERIOD OF SLEET TO THEN FREEZING RAIN WILL OCCUR THROUGH THIS
AFTERNOON AND INTO THIS EVENING. FREEZING RAIN RATES UP TO SEVERAL
HUNDREDTHS OF AN INCH PER HOUR WILL BE POSSIBLE.

DISCUSSION...AS A MID-LEVEL IMPULSE ROUNDS THE BASE OF A BROAD
EASTERN U.S. TROUGH...A TIGHTENING HEIGHT GRADIENT ALOFT WILL
ENCOURAGE STRENGTHENING SWLY FLOW AND CONTINUED/INCREASING
ISENTROPIC ASCENT ACROSS MUCH OF THE MID-ATLANTIC REGION. AS A
RESULT...PRECIPITATION SHOULD CONTINUE TO EXPAND NORTHWARD TOWARDS
SOUTHERN NEW ENGLAND. IN CONJUNCTION WITH INCREASING WARM-AIR
ADVECTION ALOFT...A MELTING LAYER WILL CONTINUE TO PROGRESS QUICKLY
NORTH...RESULTING IN A CHANGE TO A BRIEF PERIOD OF SLEET...FOLLOWED
BY FREEZING RAIN THIS AFTERNOON INTO THIS EVENING. KDOX CC DATA
CURRENTLY DEPICT THE NORTHERN EXTENT OF THIS MELTING LAYER
STRETCHING FROM SOUTHERN DELAWARE W/NWWD TO NEAR DC. BASED ON KFCX
DATA...THIS TRANSITION ZONE THEN BENDS TO THE SOUTHWEST TOWARDS
LEWISBURG WV. EASTERN PORTIONS OF THIS TRANSITION ZONE WILL ADVANCE
MORE RAPIDLY N/NW OVER THE NEXT FEW HOURS...WITH FREEZING RAIN
LIKELY OVERSPREADING THE I-95 CORRIDOR FROM DC TO NYC OVER THE NEXT
FEW HOURS. INTO THIS EVENING...SNOW ACROSS SOUTHEASTERN PA WILL ALSO
TRANSITION TO MIXED PRECIPITATION AS THE MELTING LAYER PUSHES
FARTHER N/NW. FREEZING RAIN RATES UPWARDS OF SEVERAL HUNDREDTHS OF
AN INCH PER HOUR WILL BE POSSIBLE. CLOSER TO THE COAST...SFC
WARM-AIR ADVECTION WILL GRADUALLY RAISE TEMPS ABOVE
FREEZING...RESULTING IN A TRANSITION TO RAIN.

..PICCA.. 02/15/2016

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...OKX...PHI...BGM...AKQ...CTP...LWX...RNK...RLX...

LAT...LON   37538045 38597947 39517783 41237540 41117456 40797418
            40327434 39247516 37977637 37317769 37257970 37538045

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 15, 9:52 AM EST	Mesoscale Discussion	SPC	Saint Mary's, Somerset, Wicomico	4 hr
Feb 15, 6:19 PM EST	Mesoscale Discussion	SPC	Bergen, Passaic, Sussex	5 hr
Feb 15, 2:11 PM EST	Mesoscale Discussion	SPC	Amelia, Appomattox, Bedford, Bland, Botetourt, Brunswick and 32 more	4 hr

Nearby

Mesoscale Discussions in Virginia, 2016 Mesoscale Discussions in Maryland, 2016 Mesoscale Discussions in Pennsylvania, 2016 Every mesoscale discussion in 2016

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.