Alert archive / Virginia / Mesoscale Discussions in 2016

Mesoscale Discussion 28

January 17, 2016Hertford County, Northampton County, North Carolina; 15 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Jan 17, 2016, 12:02 PM EST for Hertford County, Northampton County, North Carolina; 15 counties in Virginia. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jan 17, 2016, 12:02 PM EST (17:02 UTC)
Expired: Jan 17, 2016, 2:30 PM EST
In force: 2 hr
Issued by: the Storm Prediction Center

Counties Hertford County, NC, Northampton County, NC, City of Franklin, VA, City of Hampton, VA, City of Newport News, VA, City of Norfolk, VA, City of Poquoson, VA, City of Portsmouth, VA, City of Suffolk, VA, City of Williamsburg, VA, Gloucester County, VA, Isle of Wight County, VA, Mathews County, VA, Northampton County, VA, Southampton County, VA, Surry County, VA, York County, VA

The radar

The Norfolk radar (KAKQ), 35 km from the middle of the area, began a volume at 17:04 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

Wallops Is Stn, VA (KWAL), launched 12:00Z, 5.0 hours before the alert went out and 152 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: 1239 m above ground
0-6 km bulk shear: 78 kt
0-1 km storm-relative helicity: 58 m²/s²
0-3 km storm-relative helicity: 231 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

411 
ACUS11 KWNS 171702
SWOMCD
SPC MCD 171702 
VAZ000-NCZ000-171930-

MESOSCALE DISCUSSION 0028
NWS STORM PREDICTION CENTER NORMAN OK
1102 AM CST SUN JAN 17 2016

AREAS AFFECTED...SERN VA...NERN NC

CONCERNING...HEAVY SNOW 

VALID 171702Z - 171930Z

SUMMARY...LOCALLY HEAVY WET SNOW WITH RATES UP TO 1 IN/HR WILL
PERSIST FOR AN HOUR OR TWO BEFORE ENDING FROM W TO E...RESULTING IN
BRIEF ACCUMULATION WITH NEAR ISOTHERMAL LOW-LEVEL PROFILES NEAR
FREEZING.

DISCUSSION...RADAR TRENDS CONTINUE TO SHOW AN AREA OF BRIGHT BANDING
BETWEEN 2000-3000 FT AGL OFF THE AKQ RADAR WITH CORRELATION
COEFFICIENT PRODUCT DELINEATING A RAIN/RAIN-SNOW MIX TRANSITION ZONE
ROUGHLY NW OF AN NGU TO SFQ LINE AS OF 17Z. SE OF THIS LINE...MAINLY
RAIN IS EXPECTED EXCEPT FOR PERHAPS A BRIEF CHANGEOVER PRIOR TO THE
PRECIPITATION BAND WEAKENING.  NW OF THIS LINE...HEAVY WET SNOW
SHOULD PERSIST UNTIL RAPID DRYING FROM THE W EVENTUALLY SHUTS DOWN
THE DENDRITE PRODUCTION ALOFT.

..JEWELL.. 01/17/2016

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

ATTN...WFO...AKQ...RAH...

LAT...LON   37597551 37037609 36277697 36197708 36187733 36217746
            36337757 36657752 37137706 37407658 37587623 37687597
            37657568 37597551

Nearby

Mesoscale Discussions in Virginia, 2016 Mesoscale Discussions in North Carolina, 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.