Alert archive / Pennsylvania / Mesoscale Discussions in 2007

Mesoscale Discussion 166

February 14, 20077 states

The Storm Prediction Center issued this mesoscale discussion at Feb 14, 2007, 2:03 AM EST for 7 states. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Feb 14, 2007, 2:03 AM EST (07:03 UTC)
Expired: Feb 14, 2007, 7:00 AM EST
In force: 5 hr
Issued by: the Storm Prediction Center

All 103 counties

New Castle County, DE, Allegany County, MD, Baltimore County, MD, Carroll County, MD, Cecil County, MD, City of Baltimore, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Montgomery County, MD, Washington County, MD, Bergen County, NJ, Essex County, NJ, Hudson County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Morris County, NJ, Passaic County, NJ, Somerset County, NJ, Sussex County, NJ, Union County, NJ, Warren County, NJ, Bronx County, NY, Dutchess County, NY, Kings County, NY, Nassau County, NY, New York County, NY, Orange County, NY, Putnam County, NY, Queens County, NY, Richmond County, NY, Rockland County, NY, Sullivan County, NY, Westchester County, NY, Adams County, PA, Bedford County, PA, Berks County, PA, Blair County, PA, Bucks County, PA, Carbon County, PA, Centre County, PA, Chester County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Delaware County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Juniata County, PA, Lackawanna County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Luzerne County, PA, Mifflin County, PA, Monroe County, PA, Montgomery County, PA, Montour County, PA, Northampton County, PA, Northumberland County, PA, Perry County, PA, Philadelphia County, PA, Pike County, PA, Schuylkill County, PA, Snyder County, PA, Union County, PA, Wayne County, PA, York County, PA, Albemarle County, VA, Arlington County, VA, City of Alexandria, VA, City of Charlottesville, VA, City of Fairfax, VA, City of Falls Church, VA, City of Harrisonburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, Greene County, VA, Loudoun County, VA, Madison County, VA, Orange County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Rockingham County, VA, Shenandoah County, VA, Stafford County, VA, Warren County, VA, Berkeley County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Morgan County, WV

The radar

The Philadelphia radar (KDIX), 130 km from the middle of the area, began a volume at 07:04 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 00:00Z, 7.1 hours before the alert went out and 212 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: 527 m above ground
0-6 km bulk shear: 58 kt
0-1 km storm-relative helicity: 493 m²/s²
0-3 km storm-relative helicity: 1153 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.

000 
ACUS11 KWNS 140703
SWOMCD
SPC MCD 140703 
NYZ000-CTZ000-NJZ000-PAZ000-DEZ000-MDZ000-DCZ000-VAZ000-WVZ000-141200-

MESOSCALE DISCUSSION 0166
NWS STORM PREDICTION CENTER NORMAN OK
0103 AM CST WED FEB 14 2007

AREAS AFFECTED...MUCH OF NY INTO VT

CONCERNING...HEAVY SNOW 

VALID 140703Z - 141200Z

SNOW IS EXPECTED TO STEADILY INCREASE/DEVELOP EAST-NORTHEAST
OVERNIGHT ACROSS MUCH OF UPSTATE NY INTO VT...WITH RATES OF 1-2
IN/HR BECOMING LIKELY THROUGH EARLY MORNING.

WATER VAPOR IMAGERY DEPICTS VORTICITY MAXIMA TRANSITIONING EASTWARD
ACROSS THE OHIO VALLEY...WITH ONSET OF STRONG CYCLOGENESIS IMPLIED
ALONG THE MID ATLANTIC STATES PER BAROCLINIC LEAF SEEN IN INFRARED
SATELLITE AND STRONG PRESSURE FALLS OBSERVED VIA SURFACE DATA. DEEP
LAYER FORCING FOR ASCENT...LARGELY ATTRIBUTABLE TO ENTRANCE REGION
OF UPPER JET AND VERY STRONG LOW LEVEL WARM ADVECTION/ISENTROPIC
ASCENT...WILL CONTINUE TO INCREASE/DEVELOP EAST-NORTHEAST ACROSS
UPSTATE NY INTO WESTERN NEW ENGLAND THROUGH EARLY MORNING. 

00Z NAM/WRF-NMM 4KM FORECAST SOUNDINGS PORTRAY MODERATE TO STRONG
UPWARD OMEGA COINCIDENT WITH A DEEP DENDRITIC LAYER THROUGH EARLY
MORNING...ATOP A NEARLY ISOTHERMAL LAYER WITHIN THE LOWEST 3 KM/700
MB AND BELOW...SIMILAR TO WET BULB PROFILES FROM OBSERVED 00Z
ALBANY/BUFFALO RAOBS. FURTHERMORE...MODEL DIAGNOSTICS SUGGEST
SLANTWISE CONVECTION MAY BECOME MORE LIKELY THROUGH EARLY
MORNING...WHICH WOULD LEAD TO THE POSSIBILITY OF ENHANCED BANDING
AMIDST STRONG LOW TO MID LEVEL FRONTOGENETICAL FORCING /LARGELY
ORIENTED WSW-ENE/. WELL SUPPORTED BY LATEST SPC SHORT RANGE ENSEMBLE
GUIDANCE...SNOW RATES SHOULD STEADILY INCREASE ACROSS MUCH OF
UPSTATE NY AND EVENTUALLY INTO VT THROUGH DAYBREAK...WITH 1-2 IN/HR
RATES BECOMING COMMON.

..GUYER.. 02/14/2007

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

ATTN...WFO...BOX...OKX...ALY...PHI...BGM...AKQ...CTP...LWX...RNK...

41947417 41947341 41727298 41497286 40917319 40407407
39967485 39607560 38997670 38337756 37647857 37987907
38947910 40417844 41057773 41307688 41527600 41707509

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 14, 2:04 AM EST	Mesoscale Discussion	SPC		5 hr
Feb 14, 2:49 AM EST	Mesoscale Discussion	SPC		5 hr
Feb 14, 7:34 AM EST	Mesoscale Discussion	SPC		4 hr
Feb 13, 8:52 PM EST	Mesoscale Discussion	SPC	Garrett	5 hr
Feb 13, 8:08 PM EST	Mesoscale Discussion	SPC	Allegany, Broome, Cattaraugus, Cayuga, Chautauqua, Chemung and 19 more	5 hr
Feb 14, 12:57 AM EST	Mesoscale Discussion	SPC	Allegany, Cattaraugus, Cayuga, Chenango, Cortland, Erie and 27 more	5 hr
Feb 14, 1:15 PM EST	Mesoscale Discussion	SPC	Albany, Broome, Chenango, Clinton, Columbia, Delaware and 17 more	6 hr

Nearby

Mesoscale Discussions in Pennsylvania, 2007 Mesoscale Discussions in Virginia, 2007 Mesoscale Discussions in New Jersey, 2007 Every mesoscale discussion in 2007

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.