the 2011 groundhog day blizzard: a synoptic and mesoscale overview
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Stephen Rodriguez, Jr. National Weather Service Chicago, IL. The 2011 Groundhog Day Blizzard: A Synoptic and Mesoscale overview. Introduction. Brief background. Purpose of Study. Synoptic background and forcing mechanisms. Synoptic/ Mesoscale features: Moisture, Forcing, Instability. - PowerPoint PPT PresentationTRANSCRIPT
THE 2011 GROUNDHOG DAY BLIZZARD: A
SYNOPTIC AND MESOSCALE OVERVIEW
Stephen Rodriguez, Jr.National Weather Service Chicago, IL
Introduction Brief background. Purpose of Study. Synoptic background and forcing
mechanisms. Synoptic/Mesoscale features: Moisture,
Forcing, Instability. Conclusions.
Radar Storm Evolution
Observed Snowfall Totals
CHICAGO
Wind Gusts/Visbys/Lightning
1/4 MILEVISBYS.
65 STRIKES!
Purpose of Study Synoptic/Mesoscale Overview. Pattern Recognition/Conceptual Models. “How to Forecast” Blizzards? What are we forecasting?
Purpose - NWS Blizzard Definition Sustained wind or frequent gusts to 35
miles an hour or greater; and Considerable falling and/or blowing
snow (i.e., reducing visibility frequently to less than ¼ mile).
For a period of 3 hours or longer.
Purpose - Blizzard Elements Heavy snowfall. Snow efficiency. Strong winds.
Synoptic Overview
300 MB02/02/1100Z
Synoptic Overview
700 MB02/02/1100Z
Synoptic Overview
850 MB02/02/1100Z
Synoptic Overview
SFC02/02/1100Z
Synoptic Overview
02/02/00 00ZROAB KDVN
00Z
Low/Isallobaric Component
03Z06Z
Well-Mixed Environment
04Z RUCSounding
Moisture
850 MBMoistureTransport
Moisture
TROWAL structureidentifiable by02Z-3Z.
CHICAGO
Forcing - Deformation
Forcing - Isentropic Lift22Z/00Z/02ZRUC 290K
Persistent isentropiclift from lateafternoon throughlate evening.
CHICAGO
Forcing - Frontogenesis
RUC 02Z
ORDMSN EVV
Instability - EPV
ORD EVVMSN
RUC 02Z
Instability – CAPE/Lapse Rates
04Z RUCSounding
NORTHCENTRALILLINOIS
Snow Efficiency
NORTHCENTRALILLINOIS
00Z-03Z
Conclusions - Review Copious amounts of moisture. Persistent strong forcing due to both
synoptic/meso forcing mechanisms. Instability – an added benefit. Snow efficiency.
Conclusions – Key Factors Heavy Snowfall – Yes! Snow efficiency – Yes! Strong winds – Yes! Yes! Yes!!!
Blizzard Climatology
Conclusions – Lessons Learned Stick to “base” data. Pattern Recognition of three elements. All come together – Blizzard.
Questions? References: NOAA/NWS/Storm Prediction Center Schwartz, 2001.