Poor forecasting day after frontal passage

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Poor forecasting day after frontal passage

Postby Yucca 555 » Sun Feb 11, 2018 6:24 pm

I have noticed this for a number of decades ever since moving to Houston in 86. Today is just the latest in a recurring pattern of blown forecasts where high was predicted mid to upper 50s just 24 to 48 hrs ago. Here in Katy no higher than 39. Could have predicted this simply by looking at Amarillo temps last night. Same mistake in Houston forecasting always made every winter. No excuse.
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Re: Poor forecasting day after frontal passage

Postby srainhoutx » Sun Feb 11, 2018 7:38 pm

Technically, today's forecasted high occurred at midnight and the official temperature was 49F. That goes into the books as the official high for today. I mentioned yesterday that daytime temperatures today would likely struggle to reach the 40's as the shorter term meso guidance were detecting mid to upper 30's and low 40's near the Coast.

It is mentioned many times on this Forum throughout the Winter that the Global guidance has been running way too warm. The reason varies due to many factors, mainly a known guidance struggle with very shallow dense cold airmasses that only extend upward several hundred to one thousand feet above the surface.
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Re: Poor forecasting day after frontal passage

Postby jasons » Sun Feb 11, 2018 8:07 pm

While true, that guidance bias should be factored into the forecast. If us amtateurs can see that, the pros should too. This is nothing new.
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Re: Poor forecasting day after frontal passage

Postby TexasBreeze » Sun Feb 11, 2018 8:19 pm

Typical 5 + degrees too high in models with shallow arctic airmasses. Every time. Gets dicey when 32 degrees becomes in reach. As for rain/sleet, the models missed the band of sleet/showers across Texas for the most part today. They dried up the qpf last night for today and a band tracked across the state.
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Re: Poor forecasting day after frontal passage

Postby CrashTestDummy » Sun Feb 11, 2018 10:51 pm

I’ve noticed it, too, and it can go either way, and the temps are missed by a good margin either way. While i’ve Been planning lately for lows being ~5 deg F lower than forecast, especially when the winds are forecasted to be light, i’ve been surprised to wake up to temps ~5 deg F HIGHER than forecasted on numerous occasions lately. This usually happened when the wind shifts back out of the south overnight.

Missing the low by 5 degrees high is a pleasant surprise. Missing it 5 degrees low, and you’re killing plants.
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Re: Poor forecasting day after frontal passage

Postby brooksgarner » Tue Feb 13, 2018 2:29 pm

Many times, as was mentioned, the daytime high comes at midnight or 12:01am, then it falls all day so by afternoon it's 30 degrees colder than the recorded, "daytime high" graphic shows.

Arctic air masses are also -- as has been mentioned -- notoriously under forecast by the models due to their shallow nature. For instance, this upcoming Saturday, models are trending warmer than previously thought where it looked like 40s for highs... Now they're suggesting 60s/70s. That said, it's a cold front in February. If it does come through, we'd be hard pressed to get out of the 50s.

Experience in a region only goes so far when forecasting arctic air in Texas, when you're talking about an extended-range five to seven day outlook; I'ts best to wait a day or two before it happens to get a good grip on it because otherwise the best models in the world haven't a clue and all we can do is judge the strength of the arctic ridge at that moment and look upstream at the temperatures where it's centered. That'll usually get us within 5 degrees. MOS may show 65, progs may show 50s, but it reality it's stuck near 39 .... which seemed the case last weekend.

Another trend is that these polar air masses get here a good 12 hours ahead of the schedule proposed by the models.
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Re: Poor forecasting day after frontal passage

Postby DoctorMu » Sat Feb 17, 2018 6:11 pm

Colder than expected and a surprise boundary of rain has appeared in CLL - missed my window to mow. How we have a clear patch tomorrow morning. My mistake. :oops:
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