Sunday, January 3, 2010

Cold Coming In Waves...Snow NOT expected Here.

Alright Gang, I'm back from my trip to Arkansas where AM lows were 25-28. As I mentioned in my last blog update last Thursday, this is a well advertised cold spell coming for the next week to ten days. We will see the coldest weather in several years, however, it will be no where near the record cold snap of Dec. 1989. I see where NWS is saying mid-upper 20s north shore for tomorrow with the south shore near freezing. That sounds about right since it looks like a cloud cover may overspread us before daybreak. Tuesday morning looks colder with even colder temps for Saturday morning. Even then, it looks no worse than upper teens north shore and 24-28 southshore. Why not colder? From what I see, the East coast trough doesn't dig deep enough (like back in 1989) to force the core of the cold over us. Also, we will see some moisture ahead of the Friday cold surge, but temperatures should warm into the 50s on Thursday and all the moisture will be long gone before we get cold enough for any frozen precip. That could change and I'll have daily blog updates. Bottom line, preparations should be completed to mitigate any damage from these cold snaps. All tropical plants should be covered or moved inside. Right now citrus trees should be OK since they can handle temps in the mid to upper 20s. My basic pipe rule from my master plumber, the late Mickey Scholl states..." pipes start to have freezing problems once the temperatures get down to 28 degrees and below and (this is important) stay there for 4 hours or longer. We don't expect that overnight on the South Shore, so you don't need to run any pencil thin stream of water. Perhaps tomorrow night or later in the week. Stay tuned.

Dawn Brown's 1st day at FOX 8 is Tomorrow. I'll let you know when she'll be showing up on-air.

7 comments:

ONLYREAL said...

A cold start to day, Pre-dawn temperatures on the Southshore are hovering in the mid-30's and on the Northshore everyone is hovering around freezing. I realize this is obvious, but it’s cold! The cold will be the main story throughout this forecast, however, there will be a distinct difference between the cold in the first half of the week and the second half of the week. The difference being that the cold shot during the second half of the week will be the coldest we have experienced in Southeast Louisiana since 1989.

Today will certainly be a chilly one, but I recommend you get used to it. Highs today will struggle to reach 45F area-wide. This is the result of a modified arctic air-mass that has infiltrated the South, although the folks to our North and East are getting the brunt of it. However, the brunt of the next shot of cold air will be felt of our area and its on its way right now as I type this. The shortwave trough, which is embedded in the Northwest Flow aloft, is quickly moving in our direction. This will allow us to see freezing temperatures tonight. Another factor to us getting colder tonight will be radiational cooling, this will occur due to clearer skies and the ridge axis being closer to the area. I anticipate lows on the Southshore to be in the 28-32F range and on the Northshore I anticipate lows to fall anywhere from 22-27F. Tuesday will be a carbon copy of Monday.

Wednesday will be a little warmer due to the Sub-Tropical Jets Stream becoming active once more, meanwhile a vigorous shortwave trough and associated 1056MB dome of High pressure will be diving southeast towards to the South-central US. A surface low will be occurring Wednesday afternoon in the Western Gulf of Mexico. This low will advect some slightly warmer air into the area. You may also notice increased cloud cover and wind as cyclogenesis occurs to our Southwest. Highs on Wednesday will be around 50F on the SS. Lows will be in the Mid-30's on both sides of the lake.

Thursday is when things get interesting. On Thursday the polar shortwave trough will collide with the Sub-Tropical jet. Meanwhile, at the surface, the Surface Low and its moisture will clash with the modified Arctic Air mass that is already in place. Things should get nasty on Thursday. Precipitation should start off as rain on both sides of the Lake; however, the transition to snow will begin just North of the Louisiana/Mississippi border. As we head into the afternoon hours on Thursday, temperatures should have dropped sufficiently for rain to change over to a wintry mix on the Northshore then to all snow as time wears on. Temperatures will take a little longer to fall to favorable temperatures for snow on the Southshore, but I do think that the Southshore should get in on some wintry precipitation before the moisture leaves the area. Since this possible winter weather event is 4-5 days out, the details still need to be ironed out on who gets what precipitation type wise. Temperatures should begin to fall rapidly across the area as soon as the moisture is out of here.

The Polar front will probably be through here and probably well into the Gulf of Mexico when we wake up Friday Morning. Temperatures should be below freezing area-wide. This is a result of a 1050+MB Canadian High Pressure system and its associated Arctic Air. The polar air mass won't modify much either as it moves on in due to the extensive snow cover over the Great Plains and Deep South. Highs on Friday will likely not get above freezing. It will also be cloudy and windy on Friday so wind chills will likely be in the teens. Expect clearing Friday Night. Lows on Friday Night will likely be around 20F on the Southshore and could get as low as 15F on the Northshore. Highs Saturday will struggle to get above freezing. The lows on Saturday will be colder due to calmer winds. Lows on the Southshore could get into the mid to upper teens and the Northshore could see lows as low as 11F. Expect temperatures to begin modifying next Monday.


-ONLYREAL

ONLYREAL said...

Bob...

I LOVE you scenario for snow that I saw on tv a little while ago. I'm all jacked up and excited like a little kid. The Canadian Model (GGEM) which has been consistent, and the GFS ensembles support your forecast for snow on Saturday which will be due to a secondary Surface Low. The Brownsville NWS has now put wintry precipitation into their forecast package just because of this potential feature. If this happens (the chances are increasing)we could get in on several inches of snow. I also noticed you are 5-10F below MOS guidance in your forecasted highs, I agree with you on that also. The MOS guidance usually has a warm bias especially in winter and ESPECIALLY when you have a serious arctic outbreak like the one we have this week. I believe that MOS considers climatology into its numbers.

The bottom line is that we have lots of exciting weather in the upcoming days.

-ONLYREAL

Informant said...

Bob????

What do you think of this possibility of "several inches of snow?"

ONLYREAL said...

Bob,

I have a question. What model is used when you show the upper level winds? Particularly the model that shows the second strong shortwave that triggers the development of the Surface Low in the Gulf Friday evening? Thanks

ONLYREAL said...

The 00Z NAM shows the second shortwave diving out of Canada on Friday. If the GFS and ECMWF show it our WFO will need to make some big changes to their forecast. Bob of course would get bragging rights for forecasting it first.

Bob Breck said...

That is the GFS upper winds ONLYREAL. I don't like to look at more than 2 models. Satellite loops tell me more than models.

ONLYREAL said...

Thank You so much, Bob. Yea those satellite loops are very useful, nobody forecasted the flurries that fell from Northern LA through the Northshore today. The only model that predicted it was the Euro and that was several days ago. The only way somebody could have forecasted that was by looking at the Satellite and by going by local reports. The flurries weren't visible on radar for the most part. But honestly I didn't even think the flurries would make it as far south as they did today. The RUC sounding showed a layer of Dry air at 925H. I heard that there were some nice virgas on the Northshore this evening.