Alert archive / Virginia / Mesoscale Discussions in 2011

Mesoscale Discussion 50

January 26, 20117 states

The Storm Prediction Center issued this mesoscale discussion at Jan 26, 2011, 2:19 PM EST for 7 states. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Jan 26, 2011, 2:19 PM EST (19:19 UTC)
Expired: Jan 26, 2011, 8:15 PM EST
In force: 6 hr
Issued by: the Storm Prediction Center

All 79 counties

Kent County, DE, New Castle County, DE, Sussex 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, Wicomico County, MD, Atlantic 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, Salem County, NJ, Somerset County, NJ, Union County, NJ, Warren County, NJ, Bronx County, NY, Kings County, NY, Nassau County, NY, New York County, NY, Queens County, NY, Richmond County, NY, Adams County, PA, Berks County, PA, Bucks County, PA, Chester County, PA, Delaware County, PA, Lancaster County, PA, Montgomery County, PA, Philadelphia 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, Clarke County, VA, Culpeper County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, King George County, VA, King William County, VA, Loudoun County, VA, Louisa County, VA, Orange County, VA, Prince William County, VA, Richmond County, VA, Spotsylvania County, VA, Stafford County, VA, Westmoreland County, VA, Jefferson County, WV

The radar

The Dover AFB radar (KDOX), 80 km from the middle of the area, began a volume at 19:23 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

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 7.3 hours before the alert went out and 12 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: 435 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 121 m²/s²
0-3 km storm-relative helicity: 160 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

895 
ACUS11 KWNS 261919
SWOMCD
SPC MCD 261919 
NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-DCZ000-WVZ000-270115-

MESOSCALE DISCUSSION 0050
NWS STORM PREDICTION CENTER NORMAN OK
0119 PM CST WED JAN 26 2011

AREAS AFFECTED...NERN VA...WASHINGTON DC...CNTRL/NRN MD...MUCH OF
DE...SERN PA...MUCH OF NJ...NEW YORK CITY METRO AREA AND WRN LONG
ISLAND

CONCERNING...HEAVY SNOW 

VALID 261919Z - 270115Z

SNOWFALL WILL SPREAD INTO NERN VA...WASHINGTON DC...AND CNTRL/NRN MD
DURING THE 21-00Z TIME PERIOD...WITH RATES OF 1 IN/HR PROBABLE...AND
LOCALLY EXCEEDING 2 IN/HR FOR A BRIEF PERIOD OF TIME. SNOWFALL RATES
OF 1-2 IN/HR WILL THEN SPREAD NEWD ACROSS DE...SERN PA...MUCH OF
NJ...THE NEW YORK CITY METRO AREA AND WRN LONG ISLAND BY 00-03Z.

A PROGRESSIVE UPPER-LEVEL TROUGH LOCATED OVER THE WRN CAROLINAS AT
18Z IS FORECAST TO TAKE ON A NEGATIVE TILT AS IT EJECTS NEWD ACROSS
THE MID ATLANTIC COAST THIS EVENING. AS THIS OCCURS...OFFSHORE
SURFACE CYCLONE WILL MOVE NEWD TOWARD A POSITION S-SE OF LONG ISLAND
BY 03Z. MODEL FORECAST SOUNDINGS INDICATE THERMODYNAMIC PROFILES
ALONG AND S OF A LINE FROM NRN VA TO CNTRL NJ WILL INITIALLY SUPPORT
RAIN /POSSIBLY MIXED WITH FREEZING RAIN AND SLEET/. HOWEVER...THE
COMBINATION OF STRONG DEEP LAYER ASCENT AND STRENGTHENING LOW-LEVEL
CAA OCCURRING IN THE WAKE OF THE DEPARTING SURFACE LOW WILL FAVOR A
QUICK TRANSITION TO SNOW AS THE PRIMARY SHIELD OF PRECIPITATION
TRANSLATES NEWD DURING THE LATE AFTERNOON INTO THE EARLY NIGHT.

MODEL GUIDANCE INDICATES STRONG SYNOPTIC-SCALE ASCENT WILL BECOME
JUXTAPOSED WITH A ZONE OF STRENGTHENING LOW-MIDLEVEL FRONTOGENESIS
ALIGNED FROM NERN VA NEWD INTO NEW ENGLAND...AIDING IN INTENSE UVV/S
THROUGH THE DENDRITIC GROWTH ZONE. PRECIPITATION RATES MAY BE
FURTHER ENHANCED BY WEAK CONVECTIVE INSTABILITY ROOTED IN THE
700-600 MB LAYER. HEAVY SNOWFALL RATES ARE EXPECTED TO DEVELOP OVER
NERN VA...WASHINGTON DC...AND CNTRL/NRN MD BY 21-00Z. AS THE UPPER
TROUGH MOVES TOWARD THE MID ATLANTIC COAST DURING THE 00-03Z TIME
PERIOD...STRONG ASCENT ACCOMPANIED BY THE DEVELOPMENT OF HEAVY
SNOWFALL RATES WILL SPREAD NEWD ACROSS DE...SERN PA...NJ...AND
EVENTUALLY THE NEW YORK CITY METRO AREA AND WRN LONG ISLAND.

..GARNER.. 01/26/2011

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

ATTN...WFO...OKX...PHI...AKQ...CTP...LWX...

LAT...LON   38957818 39757748 40857507 40997375 40667332 39697391
            38477507 37657708 37937810 38957818

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 26, 7:30 AM EST	Mesoscale Discussion	SPC	Allegany, Garrett, Washington	5 hr
Jan 26, 11:19 AM EST	Mesoscale Discussion	SPC	Garrett	4 hr
Jan 26, 11:12 AM EST	Mesoscale Discussion	SPC	Bergen, Essex, Hudson, Hunterdon, Mercer, Middlesex and 5 more	4 hr

Nearby

Mesoscale Discussions in Virginia, 2011 Mesoscale Discussions in Maryland, 2011 Mesoscale Discussions in New Jersey, 2011 Every 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.