january 10-11 2009: the winter storm that “clipped” the tri-state

January 10-11 2009: January 10-11 2009: The Winter Storm that “Clipped” The Winter Storm that “Clipped”

the Tri-Statethe Tri-State

Patrick Maloit

Richard Castro

NOAA/NWS

Upton, NY

OverviewOverview

• Warning Decision Making ProcessWarning Decision Making Process• 12z cycle 9 January12z cycle 9 January

• 00z cycle 10 January – what changed00z cycle 10 January – what changed

• 12z cycle 10 January – what changed12z cycle 10 January – what changed

• What Actually Happened ?What Actually Happened ?

Warning Decision Making Warning Decision Making ProcessProcess

• How soon is too soon for a How soon is too soon for a warning?warning?• Is the event on a weekend? Is the event on a weekend?

• Once a watch/warning is up, how Once a watch/warning is up, how much do you change it?much do you change it?• How much and what has changed How much and what has changed

from the previous thinkingfrom the previous thinking

Warning Decision Making Warning Decision Making ProcessProcess

• Looking at the dataLooking at the data• Are the features well captured Are the features well captured

by the observational network?by the observational network?

• Model comparison/confidenceModel comparison/confidence• All about similarities and All about similarities and

differencesdifferences

12z Cycle on Friday January 9, 2009

Water Vapor, and 500 mb Heights and Vorticity 12z 9 Jan 2009

GFS/ECMWF/NAM 500 Hgt 12z 9 Jan

Fri12z Jan 9

Sat0z Jan 10


Sat12z Jan 10

Sun0z Jan 11


Sun12z Jan 12

GFS/ECMWF/NAM MSLP 12z 9 Jan

Fri12z Jan 9

Sat0z Jan 10


Sat12z Jan 10

Sun0z Jan 11


Sun12z Jan 12

ECMWF 500 MB Hgt/Vort and 300 mb PV - 12z 9 Jan

Sat12z Jan 10


Sun00z Jan 11


Sun12z Jan 11


Sun00z Jan 11

Sun06z Jan 11


Sun12z Jan 11

GFS/ECMWF/NAM 850 Temp 12z 9 Jan

Sun00z Jan 11

Sun06z Jan 11


Sun12z Jan 11

NAM Time/Hgt - LGA 12z 9 Jan

NAM Time/Hgt - JFK 12z 9 Jan

GFS/ECMWF/NAM 24 Hr QPF 12z 9 Jan

Sun12z Jan 11

The Afternoon Forecast – 9th• Already had Watch in effect for entire

CWA

• The fact it was a weekend necessitated going to Warnings this package

• Thermal Profile was warning/advisory line delineator

Snowfall Forecast pm of 9th

The Afternoon Forecast – 9th• Winter Storm Warnings

–All of Southern Connecticut, The Lower Hudson Valley, Northeast New Jersey, Nassau County, Northern Suffolk County, NW City Boroughs (including Queens)

• Winter Weather Advisories–Southern Suffolk County and Brooklyn + Staten

Island

00z Cycle on January 10, 2009

Water Vapor, and 500 mb Heights and Vorticity 00z 10 Jan 2009


Sun12z Jan 11


Sun00z Jan 11

Sun12z Jan 11


Sun06z Jan 11


Sun12z Jan 11

The Morning Forecast – 10th• Based on thermal profiles, adjusted all

Long Island and NYC, as well as Southern NE NJ Zones to an Advisory

• Warmer thermal profile also resulted in slight decrease in amounts

Snowfall Forecast am of 10th

The Morning Forecast – 10th• Winter Storm Warnings

–All of Southern Connecticut, The Lower Hudson Valley, Northern Northeast New Jersey

• Winter Weather Advisories–NYC, Long Island, Southern Northeast New Jersey

january 10-11 2009: the winter storm that “clipped” the tri-state

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