10749- Challenges of Winter Weather Forecasting Monday 11 am · 2016 North American Snow Conference...
Transcript of 10749- Challenges of Winter Weather Forecasting Monday 11 am · 2016 North American Snow Conference...
2016 North American Snow Conference 5/23/16
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Challenges of Winter Weather Forecasting
Along the East Coast
Challenges of Winter Weather Forecasting Along the East Coast
Sara [email protected]
Sullivan Brown [email protected]
@WeatherorNotInc/WeatherOrNotInc
913.722.3955
Weather Basics
Challenges of Winter Weather Forecasting Along the East Coast
• Moisture + Lift
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Surface Lows
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Challenges of Winter Weather Forecasting Along the East Coast
Satellite ‐Water Vapor Imageryhttp://weather.cod.edu/satrad/
• Can view stability, moisture and lift
Challenges of Winter Weather Forecasting Along the East Coast
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Most lift occurs downstream from troughs of low pressure up to the nearest ridge. Moistureis shown by the whites and blues.
Trough of Low Pressure
Ridge of High Pressure
Challenges of Winter Weather Forecasting Along the East Coast
Satellite ‐Water Vapor Imagery
Radar|K|2 N0e D D6dD = Not as simple as it looks!
‐Same color can mean different things depending on the size of raindrops, time of year, and the temperature structure of the atmosphere.‐Bugs, birds, smoke, and even the ground can look like precipitation!
Light rain
Ground Clutter
Ground Clutter
Rain
Challenges of Winter Weather Forecasting Along the East Coast
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Dual‐PolProfessional meteorologists use dual‐pol products to help differentiate between precipitation types
Boston Radar‐ Base Reflectivity and Correlation Coefficient
February 5, 2016
Challenges of Winter Weather Forecasting Along the East Coast
Weather Symbols
Light Rain
Moderate Rain
Heavy Rain
Thunderstorms with rain
Light Snow
Moderate Snow
Heavy Snow
Thundersnow
Drizzle
Sleet
Freezing Rain
S
Liquid Frozen
Challenges of Winter Weather Forecasting Along the East Coast
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Anatomy of an Observation
Challenges of Winter Weather Forecasting Along the East Coast
BDL
Location
Click Here ‐ Station Plot Explanation
Surface Observations
• Meteorologists analyze moisture, temperature, pressure, fronts, ridges, troughs etc.
http://weather.rap.ucar.edu/surface/
Challenges of Winter Weather Forecasting Along the East Coast
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Real Time Weather Resources
Challenges of Winter Weather Forecasting Along the East Coast
Northeast Surface Plots
http://weather.rap.ucar.edu/surface/displaySfc.php?region=alb&endDate=20160509&endTime=‐1&duration=0
Any US Surface Plot
http://weather.rap.ucar.edu/surface/
Excellent Real‐time Wx Data
http://weather.rap.ucar.edu/
Environment Canada WX Data
http://weather.gc.ca/canada_e.html
RWIS Data
• Road Weather Information System
– Allows for real time observations of road temperatures and atmospheric conditions.
Challenges of Winter Weather Forecasting Along the East Coast
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850 MB Temp Decision Tree
≤ 0 degrees C 0 to 3 degrees C ≥ 3 degrees C
Rds <32 Rds >32
Snow that sticks Initial SnowMelts
If heavy or cold air coming in
If light and no cold air coming in
Snow may begin to stick
Slush or just wet
Rds <32 Rds >32
Mix that sticks Initial MixMelts
If heavy or cold air coming in
If light and no cold air coming in
Mix may begin to stick
Slush or just wet
Rds <32 Rds >32
Freezing Rain
If cold air coming in
If no cold air coming in
May become freezing rain
Plain Rain
Challenges of Winter Weather Forecasting Along the East Coast
Liquid to snow ratio?
‐ Normal liquid to snow ratio in Hartford, CT is 10:1(0.10” * 10) = 1.0” of snow(0.25” * 10) = 2.5” of snow
‐ If it’s colder (near 20F), a higher ratio is needed (15:1)(0.10” * 15) = 1.5” of snow(0.25” * 15) = 3.75” of snow
‐ Sleet accumulates at roughly 3.1 (cuts into accumulations)(0.05” * 3) = 0.15” of sleet(0.20” * 3) = 0.60” of sleet
Challenges of Winter Weather Forecasting Along the East Coast
(Click Here for YOUR area ratios)
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• Most common winter weather producer: Nor’ Easters
Challenges of Winter Weather Forecasting Along the East Coast
Kocin, P. J., and L. W. Ucellini, 2004: Northeast Snowstorms Vol 1. Overview. American Meteorological Society, 53‐54 pp.
Forecasting East Coast Weather
Forecasting East Coast Weather
• Determining Snow Gradients
• Blizzard Timing and Impacts
• Ice Storms
• Effects of High Tide during Nor’ Easters
Challenges of Winter Weather Forecasting Along the East Coast
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Northeast Snow Gradients
• Caused by localized areas of strong lift
– Fronts and Instability
• In some cases, 0‐12” of snow can occur across short
distances.
Challenges of Winter Weather Forecasting Along the East Coast
Challenges of Winter Weather Forecasting Along the East Coast
February 5, 2016
Methuen, MA
Shrewsbury, MA
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February 5, 2016
Challenges of Winter Weather Forecasting Along the East Coast
• Band of moderate to heavy snow through New England
• Heavy, wet snow caused afternoon rush problems
• Downed trees, power outages, fatalities
• Deepening system and strong front in mid‐levels (850mb/~4000’) enhanced lift
• Heaviest snow fell under mid‐level front
• North (cool side) sees minimal lift, lesser snow accumulations
Challenges of Winter Weather Forecasting Along the East Coast
Concord, NH 4.3” Greenfield, MA 4.5” Ashland, NH 1.0”
Andover, MA 8.5” Petersham, MA 7.0” Laconia, NH 5.0”
Distance 42 Mi. Distance 22 Mi. Distance 14 Mi.
Snow Gradients
February 5, 2016
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Challenges of Winter Weather Forecasting Along the East Coast
February 4th 1pm
Developing mid‐level front (4000’)
http://www.spc.noaa.gov/exper/mesoanalysis/new/viewsector.php?sector=19&parm=pmsl#
21° Burlington, VT46° Cape Cod, MA
Challenges of Winter Weather Forecasting Along the East Coast
February 4th 1pm
• Very mild prior to event• Cold air slowly arriving from NW
Surface Plot
Surface Reanalysis Data
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Challenges of Winter Weather Forecasting Along the East Coast
February 5th 7am
Strong mid‐level front across southern New England
http://www.spc.noaa.gov/exper/mesoanalysis/new/viewsector.php?sector=19&parm=pmsl#
Challenges of Winter Weather Forecasting Along the East Coast
February 5th 7am
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• Deepening system off of coast• Northwest wind pulling cold air into region• Warm temps = Lower snow ratio 6:1
Surface Reanalysis Data
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Challenges of Winter Weather Forecasting Along the East Coast
February 5th 1pm
Front departing; dry, cold air arriving
http://www.spc.noaa.gov/exper/mesoanalysis/new/viewsector.php?sector=19&parm=pmsl#
Challenges of Winter Weather Forecasting Along the East Coast
February 5th 1pm
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• Low Moving NE• Snow Departing NW‐SE
Surface Reanalysis Data
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Challenges of Winter Weather Forecasting Along the East Coast
February 5, 2:03pm
Heavy Snow
Very Light Snow/Flurries
February 5, 7:03am
Light and Fine Snow
Boston Radar: Base reflectivity shown
Challenges of Winter Weather Forecasting Along the East Coast
Snow Gradients: What to Look/Listen For
Cold air in place ahead of event
Strong mid‐level front (temperature differences)
Check surface plot for snow enhancement possibilities as well
Rapid precip shut‐off (previous slide)
To find mid‐level fronts (850mb analysis): Click Here
To find surface fronts: Click Here
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Blizzards Qualifications:
• Snow/blowing snow ≤ ¼ mile visibility 3+ hrs
and
• Sustained winds or frequent gusts ≥ 35 mph
Challenges of Winter Weather Forecasting Along the East Coast
Blizzard of 2016
Challenges of Winter Weather Forecasting Along the East Coast
Union City, NJ
New York City
Maximum Amounts • Allentown, PA 31.9”• Kennedy Airport, NY 30.5”• Washington D.C. 29.3”• Newark, NJ 28.1”• Central Park, NY 26.8”• Philadelphia, PA 22.4”
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Challenges of Winter Weather Forecasting Along the East Coast
• Deepening (intensifying) low pressure to the south coupled with high pressure to the north.
• This creates a strong pressure gradient and strong winds.
• Abundant moisture wrapped into the low pressure system.
Blizzard of 2016
Credit: Paul J Kocin – Nov. 1983
For more information: Click Here
Blizzard of 2016
Challenges of Winter Weather Forecasting Along the East Coast
7am 1/22 7am 1/22
L
H
Snow
Surface Plots Surface Reanalysis Data
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1am 1/23
Blizzard of 2016
Challenges of Winter Weather Forecasting Along the East Coast
1am 1/231am 1/23
LH
Surface Plots
Snow
Snow+ Wind ≥ 20 mph (likely higher)
Surface Reanalysis Data
7am 1/23
Blizzard of 2016
Challenges of Winter Weather Forecasting Along the East Coast
7am 1/23
L
H Snow
Snow + Wind ≥ 20mph (likely higher)
Surface Plots Surface Reanalysis Data
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Blizzard of 2016
Challenges of Winter Weather Forecasting Along the East Coast
7pm 1/23
L
H
7pm 1/23
Snow
Snow + Wind ≥ 20mph (likely higher)
Surface Plots Surface Reanalysis Data
1am 1/24
Blizzard of 2016
Challenges of Winter Weather Forecasting Along the East Coast
L
H
1am 1/24
Snow
Snow + Wind ≥ 20mph (likely higher)
Surface Plots Surface Reanalysis Data
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Blizzard of 2016
Challenges of Winter Weather Forecasting Along the East Coast
Challenges of Winter Weather Forecasting Along the East Coast
Blizzard: What to Look/Listen For
Strong High to the north, cold air in place
Low pressure likely strengthening
Big pressure difference over short distance
Strong Atlantic moisture getting wrapped into the storm
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Typical East Coast Ice Storm Setups
Arctic Front W/ High Pressure Cold‐Air Damming
Cold Air Trapping Cold‐Air Damming With Cyclone
Challenges of Winter Weather Forecasting Along the East Coast
A Synoptic Weather Pattern and Sounding‐Based Climatology of Freezing Precipitation in the United States East of the Rocky MountainsRobert M. Rauber, Larry S. Olthoff, Mohan K. Ramamurthy, Dianne Miller, and Kenneth E. Kunkel Journal of Applied Meteorology 2001 40:10, 1724‐1747
December 11‐12, 2008 Ice Storm
Cold‐Air Damming With a Cyclone Event
Challenges of Winter Weather Forecasting Along the East Coast
Worcester, MAWestminster, MA
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December 11‐12, 2008 Ice Storm
• Hardest hit: Interior New England
• Ice: 1/2‐1” Iso. 1.5”
• 500,000 without power
• Massive debris removal
Challenges of Winter Weather Forecasting Along the East Coast
Cold‐Air Damming With Cyclone
Challenges of Winter Weather Forecasting Along the East Coast
• Dry and cool northeast winds at surface kept cold in place for major freezing rain event.
• Strong surge of moisture/rain over the top of surface cold.
• Surface temperatures were marginal 29‐32°, but a cooling effect caused by falling precipitation at the surface allowed for major event.
• Most icing occurred overnight.
December 11‐12, 2008 Ice Storm
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December 11th 7am
Challenges of Winter Weather Forecasting Along the East Coast
Moisture
L
Cold Air DammingMid‐level Surface
Surface Plots
December 11th 7am
Challenges of Winter Weather Forecasting Along the East Coast
Surface Reanalysis Data
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December 11th 7pm
Challenges of Winter Weather Forecasting Along the East Coast
Moisture
L
Cold Air Damming
Mid‐level Surface
Moist
Surface Plots
December 11th 7pm
Challenges of Winter Weather Forecasting Along the East Coast
• Cold dry air streaming southward• Warm side all rain• Front stalling
Surface Reanalysis Data
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December 12th 7am
Challenges of Winter Weather Forecasting Along the East Coast
Moisture
L
Mid‐level Surface
Surface Plots
December 12th 7am
Challenges of Winter Weather Forecasting Along the East Coast
L
• Front still stalled• Cold air dammed most of MA,
NH, VT, ME• Cooling effect of rain built ice• Valleys stay coolest longest
?
Surface Reanalysis Data
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Challenges of Winter Weather Forecasting Along the East Coast
Strong High to north allowing cold to set in
Surface front between cold and warm for Low to “ride” along.
Developing system pulling warm, moist Atlantic air north over surface cold.
Valley effects
For more information: Click Here
Ice Storm: What to Look/Listen For
High Tide Impacts During Nor‘Easters
• Strong winds and low pressure drive water levels up.
• Strong wind + low pressure + high tide = Maximum Storm Surge
Challenges of Winter Weather Forecasting Along the East Coast
For more info: http://www.nws.noaa.gov/om/hurricane/resources/surge_intro.pdf
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Challenges of Winter Weather Forecasting Along the East Coast
High Tide Impacts During Nor‘Easters Scituate, MAJanuary 2015 Scituate, MA
January 2014
Basic Ops Decision Tree
Snow Gradient Blizzard Ice Storm
Weak Front & Instability
Strong Mid‐Level Front & Instability
Low snow amounts
High snow amounts
Wide Convergence
Zone
Narrow Convergence
Zone
Consistent Snow Depths
Steep Snow Gradient
Weak High Pressure ‐North
Strong High Pressure ‐North
+ Weak Low + Little Moisture
Blizzard Conditions
Weak High Pressure
Strong High Pressure
+Limited moisture + Air
>32
No Icing
Dry/Cool NE Surface Winds
Moisture pulled in from
Atlantic
Challenges of Winter Weather Forecasting Along the East Coast
Plan B: heavy snow, short warning
Routine Ops
Non‐Extreme Event
Strong Low + Excessive Moisture
Steep Pressure Gradient
Additional Plan: destructive winds, debris removal, brutal plowing conditions
Rain overtops surface cold
Icing likely
Plan: Debris removal, power outages, borderline RWIS
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Challenges of Winter Weather Forecasting
Along the East Coast
Challenges of Winter Weather Forecasting Along the East Coast
Sara [email protected]
Sullivan Brown [email protected]
@WeatherorNotInc/WeatherOrNotInc
913.722.3955
Colder AirT=25
Warmer AirT = 65Td = 40
T = 20Td = 20
Cold front
Cold Fronts
Challenges of Winter Weather Forecasting Along the East Coast
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Warm Fronts (Warm Air Advection)
Colder AirT=25
Warmer Air
T = 45Td = 40
T = 20Td = 20
Warm front
Challenges of Winter Weather Forecasting Along the East Coast