IOWANick Marguccio

Brian WalderLiz Cosgrove

“America’s Heartland””

Topography- “An Inclined Plane”

What We Were Concerned About

• Start as rain, change to mix or ice, changeover to snow. (esp in the north)

• Negative tilt late?• Winds?• Temperatures above 40?

Start of the Forecasting Period18z

(Courtesy of the HPC)

12Z GFS for 18z

NEXRAD for 18z

Surface 18z

Towards the Middle3z

12z GFS for 03z

NEXRAD for 03z

Surface 03z

End of our Period12z

12z GFS for 12z

NEXRAD for 12z

Surface 12z

What Can We Can Eliminate

• Eliminated From Beginning:– Moderate Snow, Heavy Snow, Very Heavy Snow,

Blizzard, Blowing Snow, Blowing & Drifting Dust, Smoke, Wind Chill, Extreme Wind Chill, Any Type of Flood, and Severe Thunderstorm

After Looking Through Observations…

• We Eliminated:– Snow Squall, Freezing Rain, Sleet, Ice Storm, Ice

Pellets, Severe Winds, Lightning and Thunderstorm

What Verified Was….

Questionable Obs?Webster City, KEBS Zone 36

SKEW-T

Verification

COCORAHS

Dense Fog

KMCW (Zone 17)

Frost/FreezeStation KDEH, Zone 10

How We Verified High Winds

• At Clarion, IA: Zone 25– KCAV 201855Z AUTO 13021G30KT 10SM SCT043

08/M03 A2986 RMK AO2

Verifying 40 Degrees

20Z Feb 20th

MesoNet Site Data

RDC14 (Zone 10)

Recap…

• Verification Summary:• 40 degrees – All zones• Flurries- 6-11, 16-19, 25-30, 36-42, 49-55, 62-68• Snow shower - 6-11, 16-19, 25-30, 36-42, 49-55, 63-68• Light snow – 19, 28, 29, 39, 66• High Winds – 17, 25-27 ,36-39, 48- 51, 60, 61• Dense Fog – 17, 18, 39, 40, 42, 68• Freeze/Frost – 10, 29, 40, 42, 54• Liquid over .25 – 66, 67, 68

Lessons Learned

• Lessons Learned:• - Check soundings to determine the depth cold and

warm layers aloft. This helps in forecasting precip type. • - Make sure to look at ensembles. They did a good

job with precip type.• - High-Res models are good and can lead you in the

right direction, but don’t take them as gospel.• - Don’t get too focused on zones reaching a certain

temperature (in this case 40) that you forget to consider freeze/frost.