Alert archive / Pennsylvania / Mesoscale Discussions in 2004

Mesoscale Discussion 90

February 5, 20046 states

The Storm Prediction Center issued this mesoscale discussion at Feb 5, 2004, 4:41 PM EST for 6 states. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Feb 5, 2004, 4:41 PM EST (21:41 UTC)
Expired: Feb 5, 2004, 10:45 PM EST
In force: 6 hr
Issued by: the Storm Prediction Center

All 78 counties

Allegany County, MD, Frederick County, MD, Garrett County, MD, Montgomery County, MD, Washington County, MD, Cattaraugus County, NY, Mahoning County, OH, Trumbull County, OH, Adams County, PA, Allegheny County, PA, Armstrong County, PA, Beaver County, PA, Bedford County, PA, Blair County, PA, Butler County, PA, Cambria County, PA, Cameron County, PA, Centre County, PA, Clarion County, PA, Clearfield County, PA, Clinton County, PA, Crawford County, PA, Cumberland County, PA, Elk County, PA, Fayette County, PA, Forest County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Indiana County, PA, Jefferson County, PA, Juniata County, PA, Lawrence County, PA, McKean County, PA, Mercer County, PA, Mifflin County, PA, Perry County, PA, Potter County, PA, Somerset County, PA, Venango County, PA, Warren County, PA, Washington County, PA, Westmoreland County, PA, Arlington County, 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 Winchester, VA, Clarke County, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, Greene County, VA, Loudoun County, VA, Louisa County, VA, Madison County, VA, Orange County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Berkeley County, WV, Grant County, WV, Hampshire County, WV, Hancock County, WV, Hardy County, WV, Jefferson County, WV, Mineral County, WV, Morgan County, WV, Preston County, WV, Tucker County, WV

The radar

The State College radar (KCCX), 132 km from the middle of the area, began a volume at 21:42 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, 9.7 hours before the alert went out and 141 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: 2189 m above ground
0-6 km bulk shear: 53 kt
0-1 km storm-relative helicity: -13 m²/s²
0-3 km storm-relative helicity: 125 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.

884 
ACUS11 KWNS 052142
SWOMCD
SPC MCD 052141 
PAZ000-MDZ000-DCZ000-VAZ000-NYZ000-WVZ000-OHZ000-060345-

MESOSCALE DISCUSSION 0090
NWS STORM PREDICTION CENTER NORMAN OK
0341 PM CST THU FEB 05 2004

AREAS AFFECTED...MUCH OF NERN OH...WRN/CENTRAL PA...SWRN NY...FAR
ERN WV/NRN VA AND WRN/NRN MD

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 052141Z - 060345Z

FREEZING RAIN/SLEET AND SNOW ACCUMULATIONS WILL BEGIN AFFECTING THE
AREA OVER THE NEXT 2-4 HOURS FROM SW TO NE. THE LEADING EDGE OF THE
MDT-HVY FREEZING RAIN SHOULD PROGRESS TO AN AXIS FROM FAR NWRN VA TO
NERN OH BY 06/06Z. AHEAD OF THE FREEZING RAIN...A MIX OF MODERATE TO
HEAVY SNOW/SLEET WILL DEVELOP NEWD ACROSS SWRN NY...CENTRAL PA AND
NRN VA/MD OVER THE NEXT 3-5 HOURS. HOURLY LIQUID EQUIVALENT
ACCUMULATIONS AROUND 0.10 IN. WILL BE LIKELY.

A VERY STRONG WAA PROFILE EVIDENT BY REGIONAL VWP/S WAS SUPPORTING
STRONG MOISTURE ADVECTION AND LOW-MID LEVEL LIFT FROM SW-NE ACROSS
THE UPPER OHIO VALLEY/CENTRAL APPALACHIANS. LOW LEVELS PRESENTLY
REMAIN RELATIVELY DRY OVER MUCH OF PA/SWRN NY INTO NRN VA/MD...IN
CLOSE PROXIMITY TO 1036 MB HIGH CENTER OVER CENTRAL/ERN PA AT
05/21Z. HOWEVER ...THE STRENGTH OF THE LOW LEVEL WAA...AND LACK OF A
WLY COMPONENT TO THE LOW LEVEL FLOW WILL ALLOW FOR FAIRLY RAPID
MOISTENING OF LOW LEVELS IN THE NEXT FEW HOURS EAST OF THE
APPALACHIAN MTNS. ADDITIONALLY...AN ELEVATED WARM LAYER WILL
CONTINUE TO ADVANCE NWD...LIKELY SLOWING WITH TIME DUE TO COOLING
ASSOCIATED WITH STRONG MID-LEVEL VERTICAL MOTION. AS THIS ELEVATED
WARM LAYER SHIFTS NWD...MODERATE TO HEAVY SNOW LIKELY TO DEVELOP
OVER NWRN-CENTRAL PA SEWD INTO NRN VA AND NRN/WRN MD BETWEEN 05/23Z
AND 06/02Z.  THIS WILL QUICKLY CHANGE OVER TO MODERATE TO HEAVY
SLEET AFTER 06/02Z. AS THE ELEVATED WARM LAYER CONTINUES TO
DEEPEN...MODERATE TO HEAVY SLEET WILL MIX WITH AND CHANGE OVER TO
FREEZING RAIN FROM SW TO NE LATER THIS EVENING.

..CROSBIE.. 02/05/2004

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

ATTN...WFO...AKQ...BUF...CTP...LWX...PBZ...RLX...CLE...

39037962 41308112 42677855 41177736 40007715 39007697
37937786 38307904

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 5, 11:16 AM EST	Mesoscale Discussion	SPC	Adams, Athens, Auglaize, Belmont, Brown, Butler and 49 more	6 hr

Nearby

Mesoscale Discussions in Pennsylvania, 2004 Mesoscale Discussions in Virginia, 2004 Mesoscale Discussions in West Virginia, 2004 Every mesoscale discussion in 2004

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.