An Overview of the AMS Chapter/Iowa Forecast Contest (AFC)

Jeremy Grams

AMS/Iowa Forecast Contest An advanced forecast contest for ISU. Forecast different elements.

– Public: Max/Min Temps, POPs, QPF, QSF

– Aviation: Ceilings, Visibilities, and Winds.

Forecast for various days (from day 1 to 7). Square the error scoring system. Forecast again all MOS and the NWS. Forecast across central Iowa.

– 4 days per week (Mon. - Thurs.)

– Must complete 12 of the 21, 2-week & 1-week periods.

– Year-end tournament in late summer.

Schedule Sep. 12th - Sep. 22nd Des Moines Day 1 T/P/Q Sep. 26th - Oct. 6th Ames Day 2 T/P/Q Oct. 10th - Oct. 20th Ottumwa Day 2.5 T/P/Q Oct. 24th - Nov. 3rd Estherville Day 7/6/5/4 T/P Nov. 7th - Nov. 17th Marshalltown Day 1 T/P/Q/S Nov. 28th - Dec. 8th Waterloo Day 1 W/C/V Dec. 19th - Dec. 22nd AMW & DSM Day 2 T/P/Q/S Jan. 9th - Jan. 19th Mason City Day 1 T/P/Q/S Jan. 23rd - Feb. 2nd Lamoni Day 5 T/P Feb. 6th - Feb. 16th Marshalltown Day 4/3/2/1 T/P/Q/S Feb. 20th - Mar. 2nd Ottumwa Day 1 W/C/V

Schedule Mar. 6th - Mar. 9th Mason City Day 1 & 2 T/P/Q/S Mar. 20th - Mar. 30th Des Moines Day 2 T/P/Q/S Apr. 3rd - Apr. 13th Marshalltown Day 7/6/5/4 T/P Apr. 17th - Apr. 27th Estherville Day 1 T/P/Q May 8th - May 11th ALO & OTM Day 1 T/P/Q May 15th - May 25th Lamoni Day 2.5 T/P/Q Jun. 5th - Jun. 15th Mason City Day 1 W/C/V Jun. 19th - Jun. 29th Ames Day 1 T/P/Q Jul. 10th - Jul. 20th Des Moines Day 4/3/2/1 T/P/Q Jul. 24th - Aug. 3rd Waterloo Day 2 T/P/Q Aug. 7th - Aug. 17th ***Tournament***

Forecast Interval Forecast submitted by 2330z (6:30 pm CDT). Temperature

– Min between 01z to 14z. – Max between 13z to 01z.

Precipitation– 00z to 12z and 12z to 00z.

Wind Speed– Highest sustained from 03z to 18z.

Ceiling and Visibility– Minimum prevailing between 03z to 18z.

Forecast Elements All elements but temperature are categorized. POP – Cat 0 to 10 (0-100%). QPF QSF

– 0 -- 0.00" or trace 0 -- 0.0" or trace

– 1 -- 0.01 to 0.09“ 1 -- 0.1 to 1.9"

– 2 -- 0.10 to 0.24" 2 -- 2.0 to 3.9"

– 3 -- 0.25 to 0.49" 4 -- 4.0 to 5.9"

– 4 -- 0.50 to 0.99" 6 -- 6.0 to 7.9"

– 5 -- 1.00 to 1.99" 8 -- >= 8.0"

– 6 -- >= 2.00"

Forecast Elements HWS LRC

– 1 -- 0 to 3 kts 1 -- < 200 feet

– 2 -- 4 to 7 kts 2 -- 200 to 400 feet

– 3 -- 8 to 11 kts 3 -- 500 to 900 feet

– 4 -- 12 to 15 kts 4 -- 1000 to 1900 feet

– 5 -- 16 to 19 kts 5 -- 2000 to 3000 feet

– 6 -- 20 to 23 kts 6 -- 3100 to 6500 feet

– 7 -- 24 to 27 kts 7 -- 6600 to 12000 feet

– 8 -- >= 28.0 kts 8 -- >= 12000 feet or no ceiling

LRV– 1 -- < 0.5 miles 5 -- 3.0 to 5.4 miles

– 2 -- 0.5 to 0.9 miles 6 -- 5.5 to 6.4 miles

– 3 -- 1.0 to 1.9 miles 7 -- >= 6.5 miles

– 4 -- 2.0 to 2.9 miles

Verification All sites verified at airports with NWS/FAA

ASOS. POP

– Verified as 0 for no precip or trace.– Verified as 100 for 0.01” or greater.

Snowfall will be at the official NWS coop site for that city.

Anytime snow or sleet is reported by ASOS.– NWS coop sites will be used.

Verification Highest wind speed

– Highest sustained speed reported at any hourly or special observation.

Gusts are not verified.

Lowest ceiling and visibility– Any observation (hourly or special)– If variable, will use only prevailing.

Scoring Squaring the errors for differentiation.

– Divide by normalization factor. Temperature

– 1 degF = 1 errors divide by 5 = 0.2– 5 degF = 25 errors divide by 5 = 5.0– 15 degF = 225 errors divide by 5 = 45.0

POP– 10% = 1 errors divide by 2.5 = 0.4 – 50% = 25 errors divide by 2.5 = 10.0 – 100% = 100 errors divide by 2.5 = 40.0

Scoring QPF/QSF

– 1 cat = 1 errors divide by 0.5 = 2.0 – 3 cat = 9 errors divide by 0.5 = 18.0 – 5 cat = 25 errors divide by 0.5 = 50.0

HWS/LRC/LRV– 1 cat = 1 errors divide by 1 = 1.0 – 3 cat = 9 errors divide by 1 = 9.0 – 6 cat = 36 errors divide by 1 = 36.0

Normalized Scores All scores are normalized at the end of the

period.– Since not all forecasters will attempt the same

cities. Normalized score =

– [(raw score -mean)*10]/S + 80. Mean is average of all forecasts. S is standard deviation of all forecasts.

The lower your score is, the more accurate you are relative to other forecasters.

Absences Must forecast 6 of the 8 days in a period. Miss a forecast

– Assigned consensus MOS. If you know you will be absent.

– You can email me with the specific MOS or combo you want.

MOS GFS

– MAV – short-term – MEX – long-term – MEC – long-term ensemble

Eta– MET – short-term

NGM– FWC – short-term

CMO & MAVMET– Consensus of above models.

NWS Their forecasts through 2340z. Point Forecast Matrix (PFM).

– For Temperature, POP, QPF, QSF, and HWS. Terminal Aerodrome Forecast (TAF).

– For HWS, LRC, and LRV.

Year-End Tournament Head-to-head battles between forecasters.

– Will play only against another forecaster.– Winners move on to play other winners, while

losers play other losers. Seeding based on regular season scores.

How to Sign Up Will need to register with username and

password.– http://www.meteor.iastate.edu/~miraje/AFC/

Click the “Add Yourself” link on the top of the page.– http://www.weatherforecastforyou.com/AFC/add.php

Please keep your username to 8 characters and all lower-case.

Your password will be encrypted in a database, so if you forget your password send me an email.

Questions Web Site:

– http://www.meteor.iastate.edu/ams/ Click on AMS Forecast Contest link

Email:– Jeremy Grams (jgrams@iastate.edu)