Severe Weather Likely To Impact The Mid-Atlantic Sunday

For the most part, this Spring has been relatively quiet in terms of Severe Weather, but that will likely change, in a perhaps big way come Sunday.

Take a look at the expected CAPE values per the HIRES NAM model. To make it simple, the higher the number, the more likely it is for your area to receive thunderstorms. Once you begin to get into the deeper oranges and beyond, those are impressive numbers for this area, especially for the areas it is suggesting to be in the 3,000 to 4,000 j/kg range.

The image above is valid for late Sunday Afternoon/Early Evening. The corresponding simulated radar looks like this...

Notice how it is not a solid line of storms that forms, that is to be expected as this will not be a solid line of storms. It will be a broken line, hit or miss, type storms. But, the areas that do receive these storm cells have the potential of seeing a wicked storm. As this line heads southeast, the line will become stronger and there won't be as many gaps in the radar, and is why I put the southeast areas on my map in the greatest threat area.

Timing: Sunday Noon through 9 PM Sunday Night

Impacts: Torrential Rain, Large Hail, Gusty winds 60mph<, Isolated Tornadoes

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-Chris

SNOWY APRIL SATURDAY, TIMING & DETAILS

I will have to be honest, I did not expect to be making another snow forecast this year. Yet here I am, the night of April 8th, posting a snow forecast for our area that shows light to moderate snowfall totals! Summer can't get here soon enough....

With that being said, Tomorrow certainly will not be anything major, however, anytime we receive accumulating snow in April, it is pretty abnormal. Considering we are more than a week into April, I do not expect much snow to stick any roadways Tomorrow. The snow will arrive here late enough for us not to worry about snow covered roads. Now, IF the snow arrives here a bit earlier before sunrise, then some roadways have a chance of being covered.

Light snow will overspread the area between 5 and 6 am. The intensity will pick up by 7, and between 7 am and 11 am that is where we can expect the bulk of whatever snow does fall. Between 1 PM and 4 PM, most of our snow will done and over with.

Check out the 7 AM future radar via the HRRR:

Notice how narrow that swath of snow is, and the huge dry slot over Southwest PA, this is what makes me concern that my snow forecast may 'bust'. Meaning areas that I have 1-3, or even 3-5, may not receive much of anything due to this dry slot. But, for those in the "line of fire" which in this image, our area is, the snow forecast totals will definitely verify, if not over-perform in the mountainous regions.

Here's to hoping this is my last snowfall forecast of the 2015-2016 Winter Season...which is now Spring...

-Chris 

Heavy, Wet Snowstorm Targeting Central PA Overnight Saturday Through Sunday

After a very warm first few weeks of March, it is becoming apparent that our area will be dealing with a late-season snowstorm this weekend. A coastal storm will be coming up the East Coast Saturday, spreading precipitation into our area before sunrise Sunday Morning.

There is the chance the precip starts off as light rain, but once the intensity picks up, the will help cool the column and deliver with it a heavy and wet snowfall. The heaviest of the snow will arrive after noon Sunday and last through the evening hours. All precip should exit the area by Midnight Monday.

So we know there will be a storm...the question is how much snow will accumulate. There is a MASSIVE difference between snow falling and snow accumulating. Unfortunately, for snow lovers, the timing is not the best. Having the bulk of the snow fall during the daylight hours of Sunday, this will help limit the snowfall accumulations to some degree. However, if the snow falls fast enough, it will be able to accumulate without a problem. For example, you may measure 3 inches of snow 2PM Sunday, it continues to snow for the next few hours, you go out to measure at 6 PM, and you measure 3 inches again. This results from snow falling, but not rapidly enough to accumulate...again why I stress the difference between snow falling and snow accumulating.

Latest GFS:

GFS is the least aggressive with how close the coastal storm hugs the coast, however it still overspreads snow into our area and delivers light to moderate accumulations. A far cry from what the CMC and Euro are printing out.

Latest Canadian (CMC):

The Canadian is the closest to the coast with the coastal storm. This would deliver a major wet snowstorm to our area, with mixing issues nearing our area.

Latest Euro: The latest Euro is in between the GFS and CMC, but it still delivers a major, wet snowstorm to our area, although the mixing issues remain South and East of I-95.

My thoughts:

REGION A- Accumulating snow possible...mixing issues likely.

REGION B- Greatest threat for accumulating snow, perhaps significant. Will have to watch out for isolated power outages due to the weight of the snow on power-lines and tree limbs. Mixing issues possible.

Region C- All snow. Few inches possible. Too far away from the surface low to get in on the more significant accumulations.

Keep it here to my Facebook Page for the latest..should be an interesting storm to track>>>>Dauphin County Weather Facebook Page!

-Chris

Light To Moderate Snow Event Headed Our Way Thursday Night Into Friday

It is already Meteorological Spring, yet a Winter Storm is targeting our area Thursday Night into Friday.

A weak area of low pressure will be dropping out of the Mid-West and will gather a little bit of strength over Kentucky before heading Northeast from there, where it will die out somewhere over West Virginia and Southwest PA. From there, the energy will transfer to the coast, as a coastal low rapidly gains strength. This is the "wildcard" that I mentioned in my video from this morning. All guidance now has this "wildcard" low pressure remaining well out to sea, leaving the coastal areas brushed by it with minimal impacts.

I like what the latest NAM is printing out in terms of the precipitation field:

With it now being March, the Sun-Angle plays a critical role in determining whether the snow accumulates or not. Fortunately for snow lovers, the majority of this snowfall will occur during the overnight hours Thursday Night into Friday Morning. This will allow the snowfall to accumulate even on the roadways.

Speaking of timing, the snowfall should arrive here after 8 PM Thursday Night and will exit the region around Noon-Time Friday. Heaviest of the snow will occur overnight, so expect travel headaches during the morning commute Friday Morning.

FIRST CALL:

Region A: (Includes all of Dauphin County). 2 to as much as 5 inches of snowfall. I could see this storm playing out where center city Harrisburg receives 2 inches, while areas just to the North in higher elevation receives 5 inches.

Region B: A coating to 2 inches of snowfall is expected. For areas to the south, temps will hover around the 32 degree mark which will allow for the snow to struggle to accumulate. Areas further to the East, guidance is suggesting the precip to weaken as the weak area of low pressure transfers to the coastal that heads way out to sea.

Winter Storm Possible Next Week

As many of you probably already heard, there is a chance for a Winter Storm(s) next week. Before I get into the details of that threat, this weekend will feature some of the warmest temperatures the mid-state has experienced in quite some time. Temperatures Tomorrow will have highs in the middle 50s, with some areas possibly approaching the 60 degree mark, especially closer to the PA/MD border.

Sunday high temps will still reach 50, however a clipper-like system will be passing through the area dropping temps back into the 30s. As of now, expect just the chance of some light rain. There is a chance for the rain to change-over to snow as the system leaves the region. I'm not totally buying that, unless you live north of I-80. Even there, accumulations will be limited to under a couple inches. Back in SCPA, expect little to no accumulation if the rain does end as snow Sunday Night.

Now to the main event...Guidance has come into an agreement that we will have to watch two separate systems next week. One Tuesday and another Wednesday into Thursday.

There is sooooo much model disagreement right now, that I am not even going to bother to post them.

What I can tell you are the possible scenarios we are looking at.

Scenario #1: The first storm arrives here Tuesday, takes a track right on top of Central PA delivering with it rainfall. This storm takes most of the energy away from storm #2, that storm #2 is basically non-existent.

Scenario #2: The first storm takes a track and hugs the coast, putting our area on the cold side of the storm. This track would deliver at least a moderate snowfall for the region. Taking a less amplified track, leaves more energy for the second storm to have time to develop. The second storm follows the path of the first storm, hugs the coast, and delivers another moderate snowfall for the mid-state. The combination of the two would lead to accumulations well into the double digits.

Scenario #3: Instead of having two separate lows, these two lows phase and create a much bigger system. If these two systems were to phase, this would lead to a warmer and further west solution. This would likely lead to a rainstorm for us, while areas in Western Ohio receive a major snowstorm.

Scenario #4: Both the first system and the second system remain weak and take a track right along the coast. With a weaker system, heights along the coast are able to rise as the storms approach. This would likely lead to a snow to rain event for both storm #1 and #2 with little to no accumulations.

Summary: All options are on the table. I probably will not begin to get a better understanding of what is coming next week until about Sunday, but I will keep you all updated on my Facebook page with the latest>>>>> Dauphin County Weather Facebook Page!

-Chris 

Final Call On Tomorrow's Wintry Mix

Tomorrow's storm looks like it will be a bit warmer than previously expected. However, a period of snow will develop, before changing to freezing rain and then plain rain for all of the coverage area.

Timing: Snow showers overspread the area after 11 AM and will become steady after 2 PM. The transition between snow and freezing rain will likely take place between 5 PM and 8 PM. Taking a general blend of all model guidance and current observations, the freezing rain should turn to plain rain between 10 PM and Midnight Tuesday Morning. This is critical...if we can hang onto the freezing temps a little bit longer than expected, Central PA could be in for a large icing event. However, as current guidance shows, a rather quick transition to plain rain will keep ice accretion only a minor level.

Final Forecast:

Region A: Snow to start off, heavy at times. 4 to 6 inches of snowfall is expected. Changing to sleet/freezing rain to rain. Minor icing expected.

Region B: Snow to start off, 2 to 4 inches of snowfall is expected. The snow will change to sleet/freezing rain to plain rain. Rainfall amounts may exceed 1". Flooding is possible Tuesday.

Region C: A few hours of snow will transition to brief icing to rain. Snowfall amounts will remain under 2 inches. Rainfall amounts may exceed 1". Flooding is also possible on the day Tuesday.

**Dotted line**: Areas in the dotted line have the potential of seeing a significant icing event IF guidance is currently too warm. If temperatures hang around the freezing mark a few hours longer than anticipated, this region may deal with ice accretion of a quarter inch, which is certainly enough to cause scattered power outages and could bring down large tree limbs. The icing event is certainly the WILD CARD for this storm, as it is a bit unclear of how quickly our area transitions to plain rain.

Keep it my Facebook Page for the latest! Dauphin County Weather Facebook Page!

Stay safe! -Chris

2nd Call With Snowfall Amounts (Monday into Tuesday)

Only 48 hours out and yet again not much model consensus. However, it is clear that our area will start off as snow. How quickly it changes over to freezing rain, then plain rain is still an uncertainty.

Timing: Snow should overspread the mid-state between 10 am and 1 pm Monday and last for several hours. By the evening time, the transition to sleet and freezing rain will begin. By early Tuesday Morning it looks like a plain rain will fall.

UPDATED MAP:

Region A: This area will remain all snow, 8 to 12 inches of snowfall is expected.

Region B: A prolonged period of snowfall will accumulate 4 to 8 inches. A change over to freezing rain and even rain is possible.

Region C: A several hour period of snow will accumulate 2 to 4 inches before changing over to freezing rain and then plain rain. Potentially a significant amount of ice is possible. Guidance is too all over the place to put amounts regarding ice. By Tomorrow I will have a better understanding.

Region D: A short period of snowfall at the onset will accumulate a coating to 2 inches of snow.

Summary: Plan on a snowy Monday that will change over to a mix of sleet and freezing rain Monday Evening. Uncertainty remains how long we hold onto the frozen precipitation. By Midnight Tuesday Morning we should be receiving a plain rain.

Keep following my Facebook page for the latest! Dauphin County Weather Facebook Page!

-Chris