Gabriel Lojero, Mike Thomas, and Nick Gliozzi,

Lessons Learned

HPC Surface Analysis, Monday 12Z

Forecast Concern- Precip Type850 mb Analysis, Monday 12z

Forecast Concern- Precip Type850 mb Analysis, Tuesday 00z

National Radar 11:30Z

National Radar 18:30Z

National Radar 00:30Z

Verification Procedure• Eliminated all Zero Categories - Easy: Dust (14), smoke (16), Wind Chill(18,19), Flood Categories (21-24), Big Snows (5,6,7,8), and Severe Weather(27), and IceStorm (11) - Lightning (25) was ruled out based on PSU lightining data on ewall - Visibilities from ASOS reports were > 0.5 mile (17)

Verification Procedure The Search for High and Severe Winds - used Mesonet and ASOS reports and none reported winds greater than 15 kts so Snow Squall (3), High Winds (12), and Severe Winds (13) were neglected. - Even though there were 50-60kt winds at 850 mb, the layer between the surface and 850 mb was stable, not conducive for mixing to the surface.

Verifying Snow Totals

• Flurries: 18z 13th – 12z 14th using NOHRSC interactive snow information and metars

• Snow Shower and Light Snow 12z 13th – 12z 14th with same method

• Were there moderate snow totals?• Eliminated Snow Squall, Heavy Snow, Very Heavy

Snow, and Blizzard based on snow totals and other criteria

Verifying Snow Totals

• 12z 13th – 12z 14th

• NOHRSC interactive snow information

Flurries• All zones that received measurable snowfall and zones

that traced snow after 18z using NOHRSC and metars

Snow Shower• Verified using NOHRSC 12z-12z

Light Snow• Verified using NOHRSC 12z-12z

Was there Moderate Snow?

Was there Moderate Snow? (Cont.)

SLEET

Where was there sleet?

Trained spotter reports sleet.

KLRF reported ice pellets.

KPOF, just across border, reported ice pellets.

Confirming Sleet: Theory KSRC

KARG

KHKA

Confirming Sleet: Theory

Where was there sleet?

Theory Confirmed

Sleet Verification

FREEZING RAIN

Where was there Freezing Rain?

Trained spotter reports FR.

KLIT reported FR.

KPOF, just across border, reported FR.

KRUE in zone 22 reported FR.

KMEM reported FR

Where was there Freezing Rain?

Theory Confirmed

Freezing Rain Verification

Freeze/Frost• Verified using METARS

Verification Procedure• Searching for Precipitation >= 0.5 inches

Verification Procedure Precip >= 0.50 Inches Verification

• Zones 23-24, 32-33, 44, 63-64, 68-69, and 73-75

T>40 F

39

39

39

39

41

41

41

43

40

40

T>40 F Verification

Lessons Learned

• Always look at a sounding to analyze stability parameter to determine if strong winds from aloft can mix down to the surface.

• Always look at observations first to determine the most likely precipitation type during a future time period.

• Verifying Precipitation amount: Mesonet and Cocorahs• ASOS stations do not have a brain (UP = Unknown

Precipitation) . Our job to go through the data to determine what actually happened.

• You can use soundings and visibilities to get a good idea of the type of precipitation.

• GARP = Confusing interface...but great data.