Observed & Modeled Characteristics 1-3 May 2013 Upper Midwest Snowstorm Tom Hultquist - NOAA/NWS Twin Cities, MN University of Minnesota Ninth Northern

Observed & Modeled Characteristics1-3 May 2013 Upper Midwest Snowstorm

Tom Hultquist - NOAA/NWS Twin Cities, MN University of Minnesota

Ninth Northern Plains Winter Storm ConferenceSaint Cloud, MN 14-15 October 2014

Ninth Northern Plains Winter Storm Conference Saint Cloud, MN 14-15 October 2014

• Event Overview/Summary• Climatological Significance• Forecast Challenges• Reforecast Experiment

Outline

Observed & Modeled Characteristics 1-3 May 2013 Upper Midwest Snowstorm



Event Overview/Summary: Observed Snowfall

Location Snowfall (inches)Blooming Prairie, MN 18.0

Stockholm, WI 17.7

Goodhue, MN 17.5

Rice Lake, WI 17.0

Cameron, WI 16.0

Menomonie, WI 16.0

Ellsworth, WI 16.0

Ellendale, MN 15.8

Owatonna, MN 15.5

Dodge Center, MN 15.4

Rochester, MN 14.0

Ladysmith, WI 12.9

Albert Lea, MN 10.0

Eau Claire, WI 9.3



Event Overview/Summary: Synoptic Overview

Surface Evolution00Z 1 May 2013 - 12Z 3 May 2014




Surface Evolution12Z 1 May 2013 - 12Z 3 May 2014




850 mb Evolution00Z 1 May 2013 - 12Z 3 May 2014












Radar Evolution330 PM CDT 1 May 2013 – 1200 AM CDT 3 May 2014



• Some Minnesota Facts• Daily and monthly snowfall records were set in numerous

locations. The event went into the record books as depositing Minnesota's heaviest 24-hour May snowfall totals ever.•While May snowfalls are not uncommon in northern

Minnesota, heavy May snowfall in southern Minnesota is rare. A quick scan of all historical Minnesota May daily snowfall totals greater than or equal to 3.0 inches indicates that May 1938 may have been the last time any southern Minnesota observer reported snowfall totals of similar magnitude.

Climatological Significance



• Some Minnesota Facts (continued)•Minnesota's previous record statewide daily May

snowfall total was 12.0 inches. This threshold was reached twice: May 8, 1938 in Windom (Cottonwood County) and May 3, 1954 near Leonard (Clearwater County). The Minnesota State Climatology Office will now regard the May 2, 2013 snowfall measurement made in Dodge Center as the largest official 24-hour May snowfall total ever recorded in Minnesota. The Dodge Center snowfall observation made at 7:00 AM CDT on May 2 was 15.4 inches. More snow fell after observation time, adding up to a storm total of 17.2 inches.




• Some Minnesota Facts (continued)• A CoCoRaHS observer near Ellendale in Steele County

measured 17.3 inches of snow and this establishes a new Minnesota State Record for a three day snowfall in May. Ellendale's May monthly total also was 17.3 inches and this falls just short of Minnesota's all-time monthly May snowfall record of 17.8 inches set in Virginia (St. Louis County) in 1954.




• Eau Claire Tidbits• Set new snowfall record for May with 9.3”• Set new calendar day snowfall record for May with 8.7”

on May 2nd.• Set record daily snowfalls for May 2nd (8.7”) and 3rd (0.6”).• Set record low maximum temperature on May 2nd with a

high of 34°.




Climatological Significance: Standardized Anomalies

500 mb Heights18Z 1 May 2013 through 00Z 3 May 2014




Mean Sea-level Pressure18Z 1 May 2013 through 00Z 3 May 2014




850 mb Temperature18Z 1 May 2013 through 00Z 3 May 2014




Precipitable Water18Z 1 May 2013 through 00Z 3 May 2014



Climatological Significance: Historical Pattern Type

Hultquist & Schmit 2009



Climatological Significance: Historical Pattern Type

Gulf-inverted Trough Composite Mean Sea Level PressureT-48 through T+48



• Significant May snowfall is climatologically rare• Large scale pattern was not necessarily eye-catching

(standardized anomalies for large scale mass fields were not extreme)• However, interaction effects of non-anomalous fields

produced highly anomalous results.•Model forecasts underwent fairly significant shifts in

potential placement of heaviest precipitation during critical watch/warning phases of the event.• Precipitation-type forecasting was difficult, with results

hinging to a large extent on where the heaviest precipitation occurred.•Most significant snowfall occurred overnight May 1st through

the morning of May 2nd.

Forecast Challenges



Forecast Challenges: Day 2/3 vs Day 1/2 Forecasts

GFS 36-hour Forecast MSLP00 UTC 2 May 2013


































• Operational models struggled with precipitation placement leading up to the event, with a general shift eastward.• Solutions came into good agreement within 12-24 hours of

the event as upstream precipitation developed and location of precipitation axis became established.• Longer range solutions were too broad and diffuse with

forcing and resulting precipitation in comparison to shorter range runs of the same models.

Reforecast Experiment



• Reforecasts of the event were conducted to investigate how forcing evolved in consecutive simulations as the event time drew closer.• In addition, runs were conducted at varying grid resolutions

to evaluate how increased resolution would have impacted forecasts.





• WRF-ARW 3.4• GFS Initial & Boundary Conditions

• 12Z 30 April, 00Z 1 May, and 12Z 1 May initial times

• 64 km > 16 km > 4 km grid configurations• 9 Simulations• 60 Vertical Levels• Kain-Fritsch used in 64 km and 16 km

grids• WSM6 Single-moment 6-class

Microphysics Scheme• Quasi-normal Scale Elimination (QNSE)

PBL Scheme• Noah Land Surface Model w/QNSE

Monin-Obukhov Similarity Theory Surface Layer Scheme• RRTMG Long Wave Radiation Scheme• RRTMG Shortwave Radiation Scheme

Model Configuration



Reforecast Experiment: 64 km vs 16 km

36-hour Precipitation Ending 00Z 3 May 2014

60-hour Forecast

60-hour Forecast

48-hour Forecast

48-hour Forecast

36-hour Forecast

36-hour Forecast

64 km

16 km



Reforecast Experiment: 64 km vs 16 km

60-hour Forecast 48-hour Forecast 36-hour Forecast

36-hour Precipitation Difference Ending 00Z 3 May 2014

60-hour Forecast48-hour Forecast36-hour Forecast



Reforecast Experiment: So, what might be going on?44-hour Forecast

64 km vs 16 km Potential Temperature at 08Z 2 May 2014

subtle but important

differences with the 16 km solution




16 km Pot Temp & Pot Vorticity at 08Z 2 May 2014

potential vorticity generation is an

indication of latent heat

release in the model solution




64 km 2-D Frontogenesis at 08Z 2 May 2014

44-hour Forecast

16 km 2-D Frontogenesis at 08Z 2 May 2014




64 km & 16 km Omega at 08Z 2 May 2014

16 km solution more narrowly

focused and equatorward




64 km Geostrophic Saturated EPV & Theta-E Lapse Rateat 08Z 2 May 2014

64 km solution did provide

ingredients and a hint of what could occur



Reforecast Experiment: Resolution vs Precip-type 20-hour Forecast

64 km Precip-type at 08Z 2 May 2014

20-hour Forecast


20-hour Forecast



•Was a historic and challenging event.• Forecast challenges arose due to anomalous nature of event,

inconsistent model behavior, narrow axis of heavy precipitation, and precipitation-type issues.• Improvement in guidance as event drew closer in time was

likely only partially due to initial condition uncertainties. Model resolution, and the ability to accurately forecast heavy/convective precipitation at longer lead times, likely played a role in model performance.• Sets the stage for additional experiments and evaluation.• HopWRF-TS now being run at MPX to provide forecasters

with enhanced resolution guidance over a forecaster-specified 36-hour time window between 0 and 174 hours.• GFS resolution upgrade coming around the holidays

(increase from ~27 km to ~10 km)

Concluding Thoughts


Documents

Observed & Modeled Characteristics 1-3 May 2013 Upper Midwest Snowstorm Tom Hultquist - NOAA/NWS Twin Cities, MN University of Minnesota Ninth Northern