1 the historic ice storm of january 26-28, 2009. 2 outline brief review of the stormbrief review of...

1

The Historic Ice Storm of January 26-28, 2009


2



OUTLINEOUTLINE

• Brief review of the stormBrief review of the storm

• Review of the environment and forcing (Why was it so Review of the environment and forcing (Why was it so bad?)bad?)

• Latent heating just about saves the day!Latent heating just about saves the day!

• Signs of a big event – forecast confidence issuesSigns of a big event – forecast confidence issues

3



4



5



6



UNIQUE IMPACTUNIQUE IMPACT(THIS TIME IT WAS PERSONAL)(THIS TIME IT WAS PERSONAL)

• The ice storm impacted each and every one of our The ice storm impacted each and every one of our staff significantly.staff significantly.

• I was without power for 17 days! (I live within a I was without power for 17 days! (I live within a mile of the mall in Paducah, and had no specific mile of the mall in Paducah, and had no specific trauma to my house.)trauma to my house.) • Kids in school for a full week without power at the Kids in school for a full week without power at the house.house.

7

January 26-28, 2009 Ice Storm Radar


KPAH Reflectivity & METARs

6 PM Monday 12 AM Tuesday

8



KPAH Reflectivity & METARs

6 AM Tuesday 12 PM Tuesday

9

January 26-28, 2009 Ice StormEnvironment 6 PM Friday (23rd)January 26-28, 2009 Ice Storm

Environment 6 PM Friday (23rd)

10

January 26-28, 2009 Ice Storm Environment 6 PM Monday

January 26-28, 2009 Ice Storm Environment 6 PM Monday

11

January 26-28, 2009 Ice Storm Environment 12 AM Tuesday


12



13

January 26-28, 2009 Ice Storm Environment 12 PM Tuesday


14



15

January 26-28, 2009 Ice Storm Environment 6 AM WednesdayJanuary 26-28, 2009 Ice Storm Environment 6 AM Wednesday

16

January 26-28, 2009 Ice Storm Environment


850-700mbTheta-e Conv.

800mb Wind

6 PM Monday

17




800mb Wind

12 AM Tuesday

18




800mb Wind

6 AMTuesday

19




800mb Wind

12PM Tuesday

20




800mb Wind

6 PM Tuesday

21




800mb Wind

12 AMWednesday

22



Sounding At

KPAH

6 PM Monday

23



Sounding At

KPAH

12 AMTuesday

24



Sounding At

KPAH

6 AM Tuesday

25



Sounding At

KPAH

12 PM Tuesday

26



Sounding At

KPAH

6 PM Tuesday

27



Sounding At

KPAH

12 AMWednesday

28



• Classic freezing rain soundings, with a warm layer atop a sub-freezing layer at the surface.

• Lack of instability prolonged and persistent light to moderate rain rates efficient accretion.

• Latent heating sudden warming Monday night, with surface temperatures near the freezing mark.

29

January 26-28, 2009 Ice Storm Latent Heat Concerns

January 26-28, 2009 Ice Storm Latent Heat Concerns

KPAH & METARs -- 27 JAN 2009

10 AM

12 AM

2 AM

30

January 26-28, 2009 Ice Storm The Perfect Storm

January 26-28, 2009 Ice Storm The Perfect Storm

• Sub-freezing air in place for over 72 hours before storm.

• Persistent southwest flow aloft with cool northeast flow at the surface.

• Persistent low-level forcing for lift, with lots of moisture streaming into the region.

• No instability lighter rain rates efficient icing

• Latent heating continuously offset by cool northeast surface flow. Temperatures staying at or below freezing.

31

January 26-28, 2009 Ice Storm Forecast Confidence

January 26-28, 2009 Ice Storm Forecast Confidence

1. Persistent trends in successive runs of a single model. 24+ hours of consistency leads to increased confidence.

2. Personal experience can lead to forecast confidence. “I’ve seen this many times.” – pattern recognition.

3. Clustering of the operational models around a common solution.

4. #3 is a baby step toward Ensemble Forecast Systems.

32

January 26-28, 2009 Ice StormForecast Confidence

January 26-28, 2009 Ice StormForecast Confidence

33



34

January 26-28, 2009 Ice Storm Forecast Confidence Long Term


• Noticed this pattern on 4 runs of the GFS over a 2 day period. European model very similar.

• Recognized the pattern as one that could lead to an unpleasant winter scenario for our area.

• Aware that these models typically depict major large-scale events very well and very early (7-10days out).

35



ILZ094-KYZ005>009-011-211030-MASSAC-MCCRACKEN-GRAVES-LIVINGSTON-MARSHALL-CALLOWAY-LYON-INCLUDING THE CITIES OF...METROPOLIS...PADUCAH...MAYFIELD...SMITHLAND...BENTON...MURRAY...EDDYVILLE302 PM CST TUE JAN 20 2009

.MONDAY THROUGH TUESDAY...MOSTLY CLOUDY WITH A 40 PERCENT CHANCEOF RAIN OR SNOW. HIGHS IN THE UPPER 30S. LOWS IN THE UPPER 20S.

HAZARDOUS WEATHER OUTLOOKNATIONAL WEATHER SERVICE PADUCAH KY324 PM CST TUE JAN 20 2009

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

A SIGNIFICANT WINTRY PRECIPITATION EVENT IS POSSIBLE DURING THE FIRSTHALF OF NEXT WEEK

AREA FORECAST DISCUSSIONNATIONAL WEATHER SERVICE PADUCAH KY125 PM CST TUE JAN 20 2009 .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...SIGNIFICANT WINTRY PRECIPITATION LOOKING MORE LIKELY AT SOME POINT THE FIRST HALF OF NEXT WEEK.

36

January 26-28, 2009 Ice Storm Signs of a Big Event


37



38



39

January 26-28, 2009 Ice Storm Forecast Confidence Short Term

January 26-28, 2009 Ice Storm Forecast Confidence Short Term

• Successive model cycles with good clustering of major

liquid-equivalent precipitation.

• The models did not generate enough precipitation, but the inter-model consistency and consistent trend toward the extreme, increased confidence that a major event was about to unfold.

• The only question at this point, was just how bad would it be?

40

January 26-28, 2009 Ice Storm Short-Range Ensemble ForecastsJanuary 26-28, 2009 Ice Storm

Short-Range Ensemble Forecasts

• Consists of 21 individual models or model runs.

• Consists of models with different numerical guts, or the same models using slightly different observations.

• Statistics such as the mean and standard deviation can be used to quantify the variability in the forecast.

• How quickly the model forecasts diverge with time gives a direct measure of how predictable the evolution of the current environment is.

41

January 26-28, 2009 Ice Storm Short-Range Ensemble ForecastJanuary 26-28, 2009 Ice Storm Short-Range Ensemble Forecast

Leads directly to probabilistic forecasts of certain events.

-- How many members are below freezing at a certain level?

-- How many members generate a certain amount or type of precipitation?

-- How many members have winds above a certain level?

42

January 26-28, 2009 Ice Storm SREF Signs of a Big Event


SREF9 AM

Monday

Chance of FZRA

& 1”/24 hrs QPF

Valid 6 PM Tuesday

43



SREF9 AM

Monday

Chance of FZRA

& 2”/24 hrs QPF

Valid 12 AM Wednesday

44



SREF9 AM

Monday

Chance of T< 0C

@ Surface & 850mb

Valid 6 AM Tuesday

45



SREF9 AM

Monday

Mean Precipitable

Water & Showalter

Index

Valid 6 AM Tuesday

46



• The GFS and ECMWF nailed the synoptic setting for the event 7 days ahead of time.

• Model QPFs averaging ~2.5”.

• Strong signal for 1” and 2” 24 hour QPFs in the SREF.

• Extreme QPF collocated with high probability of freezing rain in SREF.

• SREF Mean indicating 250% of normal precipitable water with no instability.

47

Will it ever happen again?

Not likely, but…..

It could happen this season or next!



1 the historic ice storm of january 26-28, 2009. 2 outline brief review of the stormbrief review of...

Documents