Thursday afternoon

After a two month hiatus, I’m back again.  Weather patterns have certainly taken on a winter look early, so perhaps the coldest part of winter may well be the first half with an easing during the later winter.  But, those thoughts are just speculation at thjs point.  The forecasters I think do the best seasonal forecasting  (the gang at Weather Bell Analytics) are predicting another very harsh winter for the eastern two-thirds of the U.S.  One the best analog years is 1976-77.  If you remember, January 1977 was by far the coldest month in Louisville’s history.  That’s not to say it’s going to happen again – just that the weather patterns of the past 6-9 months are a very close parallel to the same time in 1976. And, the winter of ’76-77 ended very early.  By the second week in February, we were into a major warming trend which brought us an early Spring

Meanwhile, the “official” National Weather Service’s winter forecast continues its seemingly decades-long trend of forecasting normal to above normal temperatures for most of the country (only Texas and parts of surrounding states) are predicted to be below normal).  The NWS has had a long running warm bias in their winter outlooks and this year seems to be another in that long string of misses.  Meanwhile, the November temperature outlook issued Oct. 31 has NO area of the U.S. predicted to have below normal temperatures.  Two weeks into that outlook, we know it’s an error of huge proportions.  And, it really puts a major CAUTION sign on the rest of their current suite of products.  Time will tell, but I think Weather Bell is far closer to the truth than our government’s outlook.

WEEKEND SNOW?

Things can certainly change over two days, but at this time it appears to be a case of “How much?” rather than “Will it snow?”  Yesterday the NAM and GFS models were far apart in their solutions as to how the weekend weather pattern will evolve.  Today, they’ve come closer together, but still with different leanings.  On the big picture, both forecast snow for Saturday night into Sunday morning.  Both models expect a weak, unorganized system and thus not much precipitation.  Current estimates place accumulations of up to one inch of snow – mostly on grassy areas.  The big question for the models is What happens next?  The NAM produces a second system Sunday night/early Monday that drops a second snow, but keeps it south and east of Louisville area (watch out eastern KY, could be some heavy snows, if this pans out.)  However, as it often does, the GFS slows things on Sunday and allows a stronger secondary storm system to form.  If this scenario develops, the Louisville area will become a prime target area with a swath of 2″-4″ of snow possible.  But, it’s far too early to know how things will evolve.  More tomorrow!

Friday afternoon

Weekend weather picture seems to be getting into better focus.  One thing is a sure bet- cooler temperatures.  Should be near 80 tomorrow and 78-80 on Sunday.  Much lower humidity slowly arrives tomorrow with its full effect felt by Sunday.  The question remains about rain.

I mentioned yesterday that any rain probably would not arrive until Saturday.  Now I’m starting to ask the question, “Will we get any rain at all?”  My answer is still “yes”, but it’s a pretty shaky yes.  Right now we’ve got a little of everything – warm, humid air mass, upper level energy approaching, and lower level convergence with a weak cool front.  Perfect set-up. But, the timing is all messed up!  First, the moisture is confined to the lower atmosphere – no help from the mid-levels (a negative).  Second, the strongest surge of upper air support should pass over the area around Midnight-3 A.M.  That’s several hours earlier than the cold front.  So, the energy arrives while the moisture is confined to low levels and the cold front is not around to support lifting air (another negative).  Third, when the cool front arrives (around 8 A.M.), the upper air support will be gone but the moisture will be higher in the mid-levels.  Without the upper support, the combination of a weak cool front and marginal moisture may squeeze out a few morning showers, but they will be light (probably .10″ or less).  Any appreciable rain should be gone by Noon or 1 P.M.

So, as you can see, there are a lot of things to consider for the next 24-hour forecast.  But, here’s what I’m thinking now…

Tonight:  partly cloudy and muggy…30% chance for a brief shower or thunderstorm after midnight.   Low… 74

Tomorrow:  Cloudy in the morning with a 30% chance for light showers, then mostly cloudy and cooler during the afternoon…high…80.  Clearing and cooler tomorrow night…low…60.

Sunday:  Mostly sunny and pleasant…high…78.

Forecasting note

Yesterday morning when I checked the forecast models, I was pretty convinced that today would be rain free around here, so I was pretty surprised the weather service went as high as 40% chance for this afternoon. During the afternoon, I did a quick check of some local media sites and they were generally leaning to the “low or no” rain chances scenario as well.  So, frankly, I was surprised when the weather service forecast continued with 40% storm chance for this afternoon.  This is one of the things I found really frustrating when I was working – when they latch onto a forecast, they seem to hold on far too long EVEN when everything they are looking at is telling a different story.    (Sorry about that, but I’m trying to work through years of frustration.)

Anyway. by their morning forecast today, they had dropped down to 20%.  Still too high as the rain train had left the station by that time,  but at least an acknowledgement they were catching on.

Another forecasting point about that forecast.  In general, since Tuesday, most forecasts had both yesterday and today with highs in the 90’s.  As it turns out, an accurate forecast.  But, yesterday with the weather service’s 40% chance for rain, the high predicted for today was dropped to the upper 80s.  That’s a good move – with a higher rain chance (which would cool the air) and most likely more clouds even if rain didn’t fall,  temperatures should be lower.  However, this morning when they pretty much dropped rain out of today’s forecast, they forecast a high in the upper 80’s.  Why?  (With rain and clouds gone, isn’t it reasonable that it should be a few degrees warmer?)