Alert archive / Connecticut / Mesoscale Discussions in 2011

Mesoscale Discussion 9

January 7, 2011

The Storm Prediction Center issued this mesoscale discussion at Jan 7, 2011, 7:20 PM EST. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Jan 7, 2011, 7:20 PM EST (00:20 UTC)
Expired: Jan 7, 2011, 10:15 PM EST
In force: 3 hr
Issued by: the Storm Prediction Center

The radar

The Brookhaven radar (KOKX), 65 km from the middle of the area, began a volume at 00:23 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

Brookhaven, NY (KOKX), launched 00:00Z, 0.3 hours before the alert went out and 65 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: 510 m above ground
0-6 km bulk shear: 41 kt
0-1 km storm-relative helicity: 76 m²/s²
0-3 km storm-relative helicity: 123 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.

640 
ACUS11 KWNS 080020
SWOMCD
SPC MCD 080020 
RIZ000-CTZ000-NYZ000-080315-

MESOSCALE DISCUSSION 0009
NWS STORM PREDICTION CENTER NORMAN OK
0620 PM CST FRI JAN 07 2011

AREAS AFFECTED...PARTS OF NWRN...CENTRAL AND SOUTH CENTRAL CT AND
ERN LONG ISLAND

CONCERNING...HEAVY SNOW 

VALID 080020Z - 080315Z

MODERATE TO HEAVY SNOWFALL WITH RATES UP TO 1 INCH PER HOUR ARE 
POSSIBLE UNTIL 03-04Z ACROSS PARTS OF NWRN/CENTRAL THROUGH SOUTH
CENTRAL CT AND ERN LONG ISLAND.  TRENDS IN SURFACE OBSERVATIONS
SUGGEST THE HIGHER SNOWFALL RATES/LOWER VISIBILITIES HAVE BEEN
ACROSS CT.  IN ADDITION...THESE AREAS OF SNOW WILL CONTINUE TO
SPREAD INTO SERN CT AND SHOULD DIMINISH BY 06Z IN THAT AREA.

AT 2355Z...REGIONAL RADAR IMAGERY SHOWED TWO PRIMARY AREAS OF
PRECIPITATION /MAINLY IN THE FORM OF SNOW/ EXTENDING FROM S OF LONG
ISLAND NNWWD THROUGH CT AND THEN NWWD TO SERN NY...TO THE N OF KPOU.
THE LEADING BAND...NOW MOVING INTO SERN CT...IS ASSOCIATED WITH LOW
LEVEL WAA REGIME LOCATED N OF A BAROCLINIC ZONE WHICH EXTENDS FROM
CENTRAL/SERN NY THROUGH CT TO AN AREA OF LOW PRESSURE WELL OFF THE
MID ATLANTIC COAST /205 S KACK/.  MEANWHILE...THE SECOND BAND OF
SNOW WAS LOCATED ALONG A GENERALLY N-S FRONT MOVING EWD WITH THE
BACK EDGE OF THIS PRECIPITATION EXTENDING FROM NWRN-SOUTH CENTRAL
CT...ERN LONG ISLAND AND OFFSHORE TO 90 SSE KISP.

WATER VAPOR IMAGERY SHOWED A MIDLEVEL IMPULSE TRACKING NEWD ACROSS
CT/LONG ISLAND AT THIS TIME...WITH THIS FEATURE EXPECTED TO MOVE N
OF CT INTO VT/NH BY 06Z.  ASCENT WITH THIS FEATURE COMBINED WITH
ASCENT ALONG THE EWD MOVING FRONT AND LOW LEVEL WAA WILL SUPPORT
CONTINUED SNOW...SOME HIGHER RATES THROUGH MID-LATE EVENING.  ONCE
THE BACK EDGE OF PRECIPITATION MOVES THROUGH A GIVEN LOCATION...
SNOWFALL POTENTIAL SHOULD DIMINISH GREATLY...AND ESPECIALLY AS THE
MIDLEVEL FORCING MOVES AWAY FROM THIS REGION.

..PETERS.. 01/08/2011

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

ATTN...WFO...BOX...OKX...ALY...

LAT...LON   40827254 41307312 41637323 41807282 41757223 41667196
            41557177 41067174 40937201 40827254

Nearby

Mesoscale Discussions in Connecticut, 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.