Kansas City Winter Weather Climate Review

October 28, 2008

Created by: Mike JulyPresented by: Matthew Dux

Layout of Presentation

Review Kansas City Snow Climatology

Review Synoptic Patterns Conducive to Heavy Snow

Review Freezing Rain Climatology

There have been 1835 measurable snow events (roughly 15/yr) at the official Kansas City reporting site since 1888. Of those, only 144 events (7.8% or approximately once per season) where 4 or more inches of snow fell and only 57 events (3.1% or once every 2 seasons) where 6 or more inches of snow fell on a calendar day.

0

100

200

300

400

500

Oct Nov Dec Jan Feb Mar Apr

24 hr KC Snowfall (1888 thru Sep 2008)

>= 0.1 >= 2.0 >= 4.0 >= 6.0

•1835 Snow Events• 15 /year

•144 Events ~ >4”snow

• ~1 /season

•57 Events ~ >6” snow

• ~1 /2 seasons1634 Snow Events < 4”

30 Year Snow Climatology (1971-2000) 30 Year Snow Climatology (1971-2000)

Four Primary Patterns Favorable for Heavy Snowfall in the EAX CWA Four Primary Patterns Favorable for Heavy Snowfall in the EAX CWA

Northwest Flow System or “Clipper” Southwest Low Progressive Short Wave Trough Deepening Low

Northwest Flow System or “Clipper”

Four Primary Patterns Favorable for Heavy Snowfall in the EAX CWA

Southwest Low

Four Primary Patterns Favorable for Heavy Snowfall in the EAX CWA

Progressive Short Wave Trough

Four Primary Patterns Favorable for Heavy Snowfall in the EAX CWA

Four Primary Patterns Favorable for Heavy Snowfall in the EAX CWADeepening Low

Freezing Rain/Freezing Precipitation Climatology

30 yr average (1971-2000) – 3.2 events/yr 30 yr average (1948-1977) – 3.2 events/yr 53 yr average (1948-2000) – 3.2 events/yr

Seasonal Frequency 1948-2000

Dec-Feb72%

Rest of the Season

28%

FZRA events peak inDecember/January

Kansas City

December, January andFebruary have an equaldistribution of FZRAevents

Seasonal Frequency 1971-2000

Dec-Feb74%

Rest of the Season

26%

92% chance FZRA will occur in during the cold season (Nov-Mar). 83% chance FZRA will occur on 1 to 5 days per cold season. 58% chance FZRA will occur on 2 to 4 days (annual avg 3.2/cold season)

0

2

4

6

8

10

12

14

Number of

Seasons

0 1 2 3 4 5 6 7 8 9 10

# of FZRA Events

KC Seasonal Distribution (1948-2000)

(1971-2000) – 3.2 days/yr (1948-1977) – 3.2 days/yr (not shown) (1948-2000) – 3.2 days/yr

Kansas City Averages Kansas City Averages

Annual Mean Freezing Precipitation Days (FZRA & FZDZ)

Annual Mean Freezing Precipitation Days (FZRA & FZDZ)

Monthly Frequency of FZRA/FZDZ Monthly Frequency of FZRA/FZDZ

Primary Weather Patterns Associated with Freezing PrecipitationPrimary Weather Patterns Associated with Freezing Precipitation

Studies by Bennett (1958), Changnon (2003)and Rauber, et al (2001) came to very similarconclusions………

1) Arctic Fronts account for 42%2) Warm Front / Occlusion – 19%3) Cyclone/Anticyclone – 26%

• Pattern 3 most severe due to heavy icing plus high winds.• Area of FZRA/FZDZ is typically narrow and just north of 0C surface isotherm.

1 2

3

Summary/Other Important ItemsFZDZ occurs much more frequently than FZRA.

In KC freezing rain peaks in Dec/Jan.

Three primary weather patterns account for the vast majority of all freezing precipitation in Kansas City (possibly as high as 90%).

Between 1 and 5 freezing rain events per cold season with an annual average of 3.2/season.

Around 80% of all FZRA events occur with 2m temperatures within a tight range (28-32F) whereas the vast majority of FZDZ events occur within a much broader range (21-32F).

The Freezing Precipitation Frequency graphics from NCDC look suspect….especially for December.