Forecast Accuracy

I’ve been tracking accuracy of my forecasts for a few years but have never actually posted it online.  After getting tired of the “you guys are ALWAYS wrong” calls and emails, I figured it’s time to post the stats online:

The criteria:  I track low/high forecast temp for PDX (Portland International Airport), a central location in the metro area.  I track just my forecasts which are generally Monday-Friday.  The forecast must be within 3 degrees of the actual temp for the following calendar day.  For rainfall it’s a bit more straightforward;  if rain is forecast and it is too little to get measured at PDX I’m wrong.  Same with a no rain forecast and rain actually arrives.  In the comments section I give my thoughts and grade myself down if the numbers down seem to represent reality.  For example:  I say it’s going to rain tomorrow by late morning.  Then let’s say the rain doesn’t arrive until 11pm, leaving the day “rainy” in the climate stats, but to any normal person it didn’t REALLY rain.  Got to mark myself down some for that.  Or there is no category for “major screwups” (2-7″ unexpected snowfall 12/2009), which don’t really fall into rain/clouds or temp columns.

Chief Meteorologist Mark Nelsen

 

 

Dates	DAYS TRACKED	TEMP % CORRECT	RAIN % CORRECT	TOTAL % CORRECT	COMMENTS
2013
Jan 1-5	4 days	75%	100%	87%	Missed 1 low and 1 high.  Rain/clouds okay.
Jan 8-12	5 days	80%	100%	90%	Missed 1 low and 1 high.  Good snow dusting forecast.
Jan 15-19	5 days	50%	80%	65%	Flunked.  Chased low/high temps all week due to inversion…grrr!
Jan 21-25	5 days	70%	80%	75%	Freezing Rain forecast = Wrong!
Jan 29 – Feb 2	5 days	100%	100%	100%	Good week!  But boring weather.
Feb 5-8	4 days	80%	100%	90%	Missed one low temp
Feb 12-16	5 days	80%	100%	90%	Missed one low and one high
Feb 18-22	5 days	90%	100%	95%	Missed on high temp, rainy week = good forecast
Feb 25-1	-	-	-	-	Vacation
Mar 5-9	-	-	-	-	Vacation
Mar 12-16	5 days	90%	80%	85%	Good week, missed one low and one rain (none) day
Mar 19-23

 

 

 

 

 

 

 

 

 

 

 

 

 

2012

 

Dates	DAYS TRACKED	TEMP % CORRECT	RAIN % CORRECT	TOTAL % CORRECT	COMMENTS
2012
Jan 3-7	5 days	70%	100%	82%	Missed 3 of 10 lows/highs, rain okay
Jan 10-16	7 days	86%	100%	93%	Good week, hit weekend snow forecast well (not much in showers).
Jan 17-21	5 days	80%	90%	85%	Missed two highs, snow forecast okay, but not perfect.
Jan 24-28	5 days	60%	100%	80%	Missed 4 highs and lows…warm south wind & cold east wind battle messed me up.
Jan 31 – Feb 4	5 days	90%	100%	95%	Only missed 1 high!  A good week
Feb 8-10	3 days	67%	100%	83%	Bad week for temps, much warmer than expected.  Clouds & rain were good.
Feb 14-18	5 days	90%	100%	95%	Missed one low, otherwise great.  Fine on clouds & rain.
Feb 22-26	5 days	70%	100%	85%	Missed two lows and one high.  Challenging snow forecast turned out great though!
Feb 28 –Mar 5	5 days	80%	100%	90%	Missed two low temps, rain/snow forecasts went well!
Mar 6-10	5 days	90%	100%	95%	Good forecasts, missed first 66 day of spring, no complaints
Mar 13-16	4 days	80%	100%	90%	Missed 1 high temp, good rain/snow forecasts
Mar 19-30					Vacation
Apr 4-8	5 days	70%	100%	85%	Missed 3 highs/low, rain/clouds forecast okay.
Apr 10-14	5 days	90%	80%	85%	Missed one high and one day it rained all day instead of P.M. only.
Apr 17-21	5 days	80%	80%	80%	Missed two high temps, one day cloudier and cooler than expected
Apr 24-28	5 days	90%	80%	85%	Missed one low and one rain day
May 1-5	5 days	100%	90%	95%	Nailed all temps, but one day’s clouds and sprinkles weren’t expected
May 7-12	5 days	100%	100%	100%	Perfect!
May 14-18	Vacation
May 22-26	5 days	80%	80%	80%	Missed two high temps and big thunderstorm Saturday evening
May 29-Jun 2	5 days	90%	100%	95%	Missed one low..dry Starlight Parade!
Jun 5-9	5 days	80%	100%	90%	Missed 2 high temps, rain & sun forecast was good
Jun 11-19	Vacation
Jun 21-23	3 days	100%	100%	100%	Good short week, one nice sunny day
Jun 26-30	5 days	100%	80%	90%	Missed one rain day, otherwise good
Jul 2-6	4 days	100%	100%	100%	Great 4th of July Week!
Jul 9-13	Vacation
Jul 17-20	4 days	80%	100%	90%	Missed one high temp (too many clouds)
Jul 23 – Aug 3	Vacation
Aug 4-10	7 days	93%	86%	90%	Missed one day (clouds all day) and one high temp
Aug 13-17	Vacation
Aug 20-24	Wx Conf
Aug 27-31	5 days	90%	100%	95%	Easy forecast, sunny most days, missed one low temp
Sept 5-8	3 days	83%	67%	75%	Missed a high temp and surprise t’storms in Portland late afternoon.
Sept 12-16	5 days	90%	100%	95%	Missed on high temp (too cool)
Sept 25-28	4 days	75%	75%	75%	Missed one high and one low, plus too cloudy/wet of a forecast one day
Oct 2-5	4 days	75%	100%	87%	Missed two low temps, annoying east wind dropped off = cold.
Oct 9-12	4 days	75%	100%	87%	Missed two high temps, bad week
Oct 16-20	5 days	90%	100%	95%	Missed on high temp, good week otherwise
Oct 23-27	5 days	80%	100%	90%	Missed one high and low…warm south wind arrived too early
Oct 30-2	4 days	100%	100%	100%	100%!!!  Temps all within 3 degrees, off/on rain all week well forecast
Nov 6-9	4 days	63%	80%	71%	Yikes!  A brutal week, missed almost half the temps
Nov 12-15	4 days	100%	80%	90%	Temps perfect, but fog didn’t clear off in a reasonable fashion one day.
Nov 20-26	5 days	80%	100%	90%	One high and one low missed, rain okay
Nov 28-Dec2	5 days	90%	100%	95%	Missed on high temp, otherwise a good week.
Dec 4-7	4 days	62.5%	100%	81%	Bad week, missed 3 low/high temps, rain/clouds okay.
Dec 11-15	5 days	70%	80%	75%	Major miss, forecast big windstorm; it didn’t show up
Dec 18-22	Vacation
Dec 26-30	5 days	80%	100%	90%	Missed one high/low, very dry week.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Pre-2012

2011	FCST DAYS	TEMPS CORRECT	RAIN & CLOUDS CORRECT	FINAL GRADE	COMMENTS
Jan 3-9	5 days	60%	100%	80%	Missed 2 lows, 2 highs…I hate east wind.
Jan 10-14	5 days	80%	80%	80%	Dry one day w/rain fcst.  Missed one high & one low
Jan 17-20	4 days	88%	100%	94%	Missed one high temp
Jan 24-27	4 days	88%	80%	84%	Missed one high temp and forecast rain when only a sprinkle or two fell.
Jan 31-Feb 7	5 days	90%	100%	95%	Only missed one low temp by 4 deg.
Feb 8-11	4 days	80%	100%	90%	Missed one low temp…good week
Feb 15-19	5 days	70%	80%	75%	Rough week, missed 3 highs/lows and one wet day when expected dry.
Feb 22-26	5 days	100%	100%	100%	Snow & cold week…100% highs and hit snow amounts well!
March 1-3, 6-7	5 days	70%	100%	85%	Missed two lows and one high…dog chasing it’s tail while forecasting?
March 8-11	4 days	62%	100%	81%	Missed almost ½ of highs & lows…rain forecast perfect though.
March 15-19	5 days	80%	100%	90%	Missed one low and one high…rained every day!
March 22-26					Vacation
Mar 29-Apr 2					Vacation
April 5-9	5 days	80%	80%	80%	Missed two lows, and one dry day not expected.
April 12-16	5 days	80%	80%	80%	Clouds/Showers Saturday, bad forecast.  Missed high & low too!
April 20-23	4 days	75%	100%	87%	Missed two low temperatures
April 26-30	5 days	90%	80%	85%	One day w/no rain when forecast.  Too cool for one high temp.
May 10-14	5 days	70%	100%	85%	Missed one high and 2 lows
May 17-20	4 days	100%	100%	100%	Excellent week, everything worked out right!
May 25-29	5 days	80%	90%	85%	Missed one low, one high, and slightly missed a showery day (drier than expected)
May 31-Jun 4	5 days	100%	100%	100%	A great week!  No missed temps, plus accurate forecast of first real warm weather (timing & temps)
June 5-10	5 days	80%	100%	90%	Missed two high temps, forecast too warm.
June 14-17	4 days	75%	100%	87%	Missed a low by…well…7 degrees!  Otherwise a good week.
June 20-24					At Weather Conference
Jun 28-Jul2	4 days	83%	100%	92%	Only missed one high by one degree, good otherwise
July 6-8	3 days	67%	100%	84%	Ouch…missed a high and low
July 9-17					Vacation
July 19, 21, 22	3 days	67%	100%	84%	Missed a low and just barely a high.  Showers in mid July!
July 22-Aug 7					Vacation
Aug 8-12	5 days	70%	80%	75%	Challenging marine layer!  Missed 3 lows/highs, plus cloudy day.
Aug 16-19	4 days	100%	100%	100%	Perfect week!
Aug 23-27					Vacation
Aug 30-Sep 3	5 days	100%	100%	100%	Perfect week!
Sept 6-10	5 days	80%	100%	90%	Missed one high and one low.  Clouds/rain forecast was “spot on”
Sept 13-17	5 days	30%	60%	45%	Worst Ever!  Missed numerous highs/lows due to marine clouds, then unexpected rain.
Sept 20-25	6 days	83%	100%	92%	Much better.  Just missed two low temps by more than 3 degrees.
Sept 27-Oct 1	5 days	80%	80%	80%	Missed one high and one low (out of 10), rained one day (not fcst)
Missing
Oct 18-23	6 days	58%	83%	71%	Bad week, missed 5 of 6 lows (warm nights).  Clouds/precip fcst okay.
Oct 25-28	4 days	100%	100%	100%	Yes!  Finally a good week; good forecasting.
Nov 1-5	5 days	60%	80%	70%	Missed 4 of 10 temps…ugh!  One cloud/rain day was missed.
Nov 8-12	6 days	83%	100%	92%	A good week, extra work day
Nov 15-19	5 days	70%	100%	87%	Inversion screwed up high temps on 2 days, one low temp missed
Nov 22-23, 26	3 days	83%	100%	92%	Missed one low temperature
Nov-Dec 29-4	5 days	80%	90%	85%	Missed two high temps (too much fog), and one day fog barely burned off.
Dec 6-7, 12	3 days	67%	100%	83%	Missed one high and low temp, clouds/rain okay.
Dec 27-Jan2	6 days	91%	100%	95%	Missed one high temp

Dates	DAYS TRACKED	TEMP % CORRECT	RAIN % CORRECT	TOTAL % CORRECT	COMMENTS
2010
Jan 5-9	5 days	100%	100%	100%	A bit better!
Jan 11-15	5 days	90%	100%	95%
Jan 18-22	5 days	90%	90%	90%	Missed a high one day and marginal rain forecasting = -10%
Jan 25-27	3 days	50%	67%	58%	Flunked!  Missed rainy day and 2 bad temp forecasts
Feb 2-6	5 days	100%	90%	95%	Saturday: Cloudier and drippy (-10%)
Feb 9-13	5 days	40%	100%	70%	A massacre: All 5 days high temps off by 4 degrees+!
Feb 16-20	5 days	70%	100%	85%	Two sunny days my highs were too low.  No one minds those mistakes right?
Feb 23-27	5 days	90%	100%	95%	A good week!
March 5-13	5 days	70%	100%	75%	3 out of 10 temps missed…bad
March 16-Apr 1	Vacation	-	-	-	-
Apr 6-10	5 days	80%	90%	85%	A decent week
Apr 13-17	5 days	90%	80%	85%	1 morning colder than expected: Saturday T’Storm = Bad!
Apr 20-26	5 days	90%	100%	95%	Pretty good week, missed one low
April 29-May 2	4 days	100%	80%	90%	Surprise rain one day earlier than expected
May 4-8	5 days	80%	80%	80%	Surprise PM Showers in spots on “Mostly Sunny” day!
May 11-15	5 days	90%	100%	95%	Missed one low temp
May 25-29	5 days	60%	100%	80%	Brutal misses on temp forecasts, rained every day, so okay with that.
June 8-12	5 days	80%	90%	85%	Showers one day when not in forecast…bad.
June 16-20	5 days	80%	80%	80%	Missed 2 highs and rained one day when supposed to be dry.
June 29-July 3	5 days	100%	60%	80%	2 days with downpours when only a sprinkle expected.  Vancouver soaked 1”+
July 6-9	4 days	80%	100%	90%	Easy week, sunny & hot, nailed heatwave
July 13-17	5 days	90%	100%	95%	Good week, sunny & dry, missed one low temp
Aug 24-28	5 days	70%	90%	80%	Rough temp forecasts…missed 3 of 10!  One day w/showers not expected on weekend.
Aug 31-Sept 4	5 days	90%	100%	95%	Good forecasting, hot weather okay, hit first good rain in 2 months correctly!
Sept 7-11	5 days	90%	90%	90%	Technically correct on rain/weather, but took off 10% because Fridaylow clouds took ALL day to turn to “PM Sunshine”.
Sept 14-18	5 days	60%	100%	80%	Challenging week with temperatures.  Cloud cover screwed up 4 high & low temps…grrr!
Sept 19, 21-24	5 days	100%	100%	100%	A very good week.  Things finally worked out perfectly for once.
Oct 4-9	5 days	80%	100%	90%	Not too bad, missed two lows
Oct 19-23	5 days	80%	100%	90%	Good forecasts in general, but 2 nights warmer than expected
Oct 26-30	5 days	90%	100%	95%	Missed one low temp, but good otherwise.
Nov 1-5	5 days	100%	100%	100%	Wow!  Everything worked out perfectly for once.
Nov 9-13	5 days	90%	100%	95%	Missed one low temp (colder than expected).  Rainfall was good.
Nov 15-20	6 days	100%	100%	100%	Great Week!
Nov 22-26	—				Only forecast 2 days
Nov 29-Dec 3	4 days	67%	100%	83%	Missed 3 of 8 temps, good rain fcsts though.
Dec 7-9	3 days	100%	100%	100%	Great Week!
Dec 13-16	4 days	87%	100%	93%	Missed one high, a 55 deg. Day…warm
Dec 20-24	—				Vacation Week
Dec 27-30	4 days	70%	100%	85%	Missed 2 highs and 1 low
2009
Nov 24-30	5 days	70%	100%	85%
Dec 1-5	5 days	60%	100%	80%	Lots of bad lows, dry week
Dec 8-12	5 days	80%	80%	80%	Missed 1 hi & 1 lo.
Dec 14-27	None				Lots of vacation
Dec 29-Jan 2	4 days	63%	100%	82%	Snow disaster =  subtract 50%!