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By: cws6196, 4:43 AM GMT on February 18, 2008
Friday Morning Update
The main roads are fine; the local roads are getting slick. My forecast stays on track, yet the timing seems to be off as the change to sleet has occurred an hour or so earlier then I thought. This could be a good sign as to a change over to all rain could be sooner. Surface temps are still well below freezing, yet the warm air is above us. The sleet will eventually change to freezing rain as the warm air lowers. I will say the change to rain could occur by the afternoon commute, but only time will tell.
Thursday late evening Update
A look at the model data still confirms my previous forecast, so no changes at this time. I will add though the chance for fog Friday afternoon into the evening given the low level moisture, warm air aloft and lack of wind. So while driving on the ice you also won't be able to see where you are going ... please be careful.
Thursday Afternoon Update
I am sending this update to say there is no update. The current data and radar images still support my forecast. There is still discrepancy in the model data as to when the change over to freezing rain will occur. I am sticking with my forecast of 8:00 to 10:00 am. There is also discrepancy as to how warm it will get Friday. The models tend to bring in warm air to the surface very early in the day, but I remain skeptical of that solution. There will be warm air aloft (upper atmosphere), hence the freezing rain, but I don't see it quickly filtering down.
The NWS has stated they will update the current Watch and possibly add Warnings after 4:00pm today.
Wednesday Night Update
Friday is looking to be a mess, and somewhat worrisome for the NWS as they have already issued a Winter Storm Watch for the event. Basically I am sticking with my previous forecast posts regarding Friday. I will add a bit more snow then I previously thought, and I will try to add time frames for the event. So here goes ...
The cold air will be difficult in moving out of here, especially at the surface, so I am now looking at more snow in the beginning. Snow accumulations could be up to 3 inches or more, especially for those closer to the PA line. Then there will be a change over to freezing rain which will last quite a long time. This is concerning given the projected liquid levels as shown in the models (if this were an all snow event we would have about a foot of accumulation). I do see the very real potential for a thick layer of ice on the ground, somewhat worse then we saw last Tuesday.
For the time frames, I see the snow beginning Thursday evening around 10:00 or so (depending on your location relative to South or North) extending through the early portion of Friday morning. The change over from snow to sleet / freezing rain takes place right about rush hour, around 8:00 to 10:00 am and will last all day. I don't forecast a change to all rain until after Midnight or even into the morning of Saturday. It is hard to say as I am not confident the cold surface air will be warmed all too quickly given the cold temps to start, the cloud cover and the frozen precip on the ground.
Late Tuesday Update
It only gets better and better. This is not an easy forecast for many reasons: not much model data agreement, uncertainty of actual temps, how 'wierd' this Winter has been thus far. One quick note as to why there was no precip early today: the lower atmosphere was too dry. Anything that did fall evaporated before we could see it. Ok, on to Wednesday and Friday.
Wednesday: clouds will move in as the day progresses and the frontal system moves closer to our area. At this time it appears any snow we do get will be around the evening commute. Maybe an inch for those who get snow; a mix of precip for others. Those around Baltimore (except those South) have a greater chance to see snow in the afternoon. West and closer to the PA line have even a greater chance. All precip should move out by Midnight. The timings I mention are based on current forward progress. I don't foresee much change in this, but if it happens I will let you know.
The next system will affect us Friday. Again a tricky situation given varying temps in different layers of the atmosphere and surface. The cold air should still be around, and temps at the surface should be around freezing. There are pockets of warming upward into the atmosphere. Therefore, I am envisioning Friday to resemble last Tuesday; mixed precip with mainly freezing rain. There could be some snowfall, but I really see this more of a frozen precip event. This will occur Friday morning into the afternoon, depending on your location (moving in a NE direction).
Update Feb 18
First, before I get into the 'fun' stuff, please note there is a "slight" chance for snow Tuesday afternoon. Temps may be too high for it to stick, but in local areas it could be heavy and therefore stick.
Ok, on to the 'fun' stuff. My previous post is still on track, although the timing has shifted somewhat earlier. We are now looking at a Wednesday event and then another Thursday into Friday event. Didn't I say it would be 'fun'? The models still differ, but not as much as previous runs. Also, some historic patterns are being seen wherein maybe there is a learning curve to how this Winter season is working in a La Nina pattern.
Concerning Wednesday: the factor here is how cold the surface temps will be. The air aloft will be cold enough for snow, that is a given. The models show the ground temps well above freezing, but I am not sure that is accurate given the cold air aloft and the cloud cover keeping the temps down, adding to it a cold Tuesday evening. If these temps stay down the precip from the clipper system will be snow. Here is what the local NWS said: "This clipper is reminiscent of the one that brought advisory level snow to the area back on 05 Dec 2007. Like the Dec 2007 clipper...model guidance initially downplayed both the precip potential and the dynamics. Am concerned current guidance is on the same path."
Then we have Thursday into late Friday. Again to quote the local NWS: "This next system has the potential to bring significant wintry precipitation to region and needs to be closely monitored." For now I will not add anything else to that given my previous post already stated this and the uncertainty of the models.
Feb 17 entry
Don't be too lulled by the nice weather ... it is still February. The end of the week into the weekend is unsettled at this time. The model data is not consistent, so I don't have too much confidence at this moment in what will truly happen, but as the model data becomes more consistent I will have a better idea. So why even mention anything now? Because the model runs that show rain this weekend could be correct; and the runs that show mixed precip or snow could be correct. So I figure I would give you all a heads up.
The issue is a front moving in on Thursday and where it eventually stalls and the temps at the time. My best prediction would be mixed precip turning to rain Friday and Saturday. But we shall see.
The other issue of interest is the model data showing a coastal Low forming Sunday and the advancement of a cold front. This typically is the set up for major snow for our area, but with this Winter, this set up has brought us only a dusting of snow but mainly rain. So, worth watching, but not worth running out to the store just yet.
Updated: 2:42 PM GMT on February 23, 2008
By: cws6196, 4:31 AM GMT on February 12, 2008
More Severe then Thought
Update: The cold air lingered longer then I first thought and more icing accumulated in the area.
Never know what this Winter will bring. Today, in Central MD, the cold air will begin to be pushed out by warmer Gulf air from the South. But, there is a system to the West of us moving into the area. Precip will begin as snow, change to sleet, then to all rain closer to Midnight.
Those West of Baltimore and toward the PA line could see an inch or 2 inches of accumulation. Everyone else will see mainly frozen precip and a quicker change to rain. Keep in mind that the warm air is moving in from the South, so those closer to Baltimore and South and East will see the change over much earlier.
Updated: 12:54 PM GMT on February 13, 2008
By: cws6196, 4:25 PM GMT on February 11, 2008
As recorded by my weather station, yesterday (Sunday) I had a peak gust of 40 mph (elevation 20 feet). This morning (Monday) recorded a wind chill reading of -11F.
By: cws6196, 4:33 AM GMT on February 06, 2008
The weather pattern really looks like a Spring type pattern for Central Maryland. The system producing the severe weather in the South East is heading this way, but we will not see that type of weather given the conditions in our area. For most in Central Maryland, the storms will begin in the later afternoon into the evening (depending on the movement of the front). Conditions do not appear to be favorable for either tornadoes or hail. What does seem likely are localized strong thunderstorm activity. Strong wind could be a factor.
One bit of caution though: even though the conditions do not seem right for tornadoes, given the nature of the system and the mixing air masses, please be aware of your area as any storms approach. Spring-like systems can be unpredictable.
Temps will drop Wed night as the cold front moves through. There is some talk of snow Saturday, but right now I think most of us will see more of a mixed precip or rain.