As the headline implies, most of this discussion will be dedicated to the Sun/Mon timeframe, but all periods will be covered.
Currently: Pac High press in WV, w/warm front into NNE, so a pleasantly warm day across the area.
Tonight: W/cloud cover and no real cold air to speak of (yet), temps will be close to guidance in the fcst, basically within a few deg of freezing everywhere in the state.
Tomorrow: Cold air begins to rush in. I went way below temp guidance, as I just can't see any reason that temps would rise as much as it shows. Temps rebound a few deg, to the mid to upper 30s, before they begin to fall again. Winds will pick up by midday, and gust to 40-45 MPH as the gradient between an ocean storm and the arriving cold air mass sharpens. It is not impossible for a wind advisory to be needed, esp for E CT.
Tomorrow Night/Sat: The core of the Arctic air mass moves in. Winds will diminish after midnight tomorrow night, but it will still be breezy thru the day Sat. Except maybe if we can downslope along I 91, the entire state will stay below 20 degrees throughout the day! I went very close to guidance on temps, except a bit warmer in the CT Valley.
Long Term: The long term concern revolves around a major storm system for later Sun into Mon.
So on Sun, clouds increase, but I'll keep the day period dry, as precip should not arrive until well after dark. I kept temps close to guidance. On one hand, you have strong warm air advection. On the other hand, you have increasing clouds and not much solar contribution. So figuring these two are a wash= follow guidance temps. Highs should be somewhere around 30 degrees across the state.
Precip should arrive by midnight Sunday night. I think we start as snow everywhere, except maybe the extreme SE coast. We will probably change to rain, or at least non-snow everywhere, fairly quickly as warm air races in w/the low tracking to our west. In general, advisory level snows are likely for most places, except the extreme SE coast, where near zero is likely.
Now, part of the problem will be if we go directly from snow to rain or if there are other precipitation types in between. I am not going to fcst any freezing rain at all. To get freezing rain in this part of the world, you generally need to have a mechanism to lock cold air in at the surface, but completely scour it out of the upper levels. That is not the case here. I was originally thinking that this would be pretty straightforward just snow to rain, but some of the new 12Z guidance has thrown me a bit of a curveball, in that they are developing a 2ndary "mesolow" off the coast of NJ. If this is true, sfc winds would back around more to a NE direction and lock in more cold air. However, most of the damage aloft would be done and this could create an extended period of sleet. This is a relatively new feature on the modeling, so it bears watching for potential adjustments or if it exists at all.
The next problem is wind. Just based on pressure gradient alone, winds should easily gust to 50 MPH at times everywhere. Some models have been producing a "sting jet" feature, which, if real, would produce wind gusts up to 70 MPH for a time Mon morn. Since we're still a little ways out, I have included gusts to 50 MPH for now, but no higher. When we see if the sting jet feature is real and can nail it down, we can bump the fcst up if necessary. On the back side of the low, later Mon, winds should gust to 40 MPH or so. This is the "easy" part of the wind fcst, as winds are much easier to fcst on the back side of storms in this part of the world.
Flooding should not be a major issue. Total QPF is 1-1.25", w/maybe some higher amounts. Ordinarily, on frozen ground, this could present flooding issues. However, we have fairly dry antecedent conditions, so we should be OK. Nuisance urban flooding is possible.
Flash freeze could be a concern later Mon, as cold air funnels in. It will be a race between temps getting back to freezing and winds drying out the ground. Later crews can have a look at that and issue any statements as necessary.
As far as temps, the high temps I have are close to guidance, w/some tweaks here and there and generally in the low 40s. It should be noted that these highs occur Mon morn, w/temps falling thru the day after that.
For Tue, a fair, but chilly day is in store. Guidance temps look very good and are generally accepted. High temps should be 30-35 degrees. Winds will still be up behind the departing storm and could gust to 35 MPH at times.
For Wed, a clipper system will pass by to the north. This could bring a brief snow or sleet shower w/it, esp to N CT. I went fairly close to guidance temps, w/some adjustments here and there. Look for highs generally in the mid to upper 30s.
For Thu, strong cold air advection develops behind the clipper system. For this reason, and w/models typical day 5 and beyond biases at resolving changing air masses, I went quite a bit below guidance temps. Look for highs near 30 degrees across the state.
In the long range, look for a continuation of a cold to very cold pattern w/ample storm opportunities. Right now, most of the storms look to be of the clipper variety, which usually deliver light snow and reinforce the cold air. However, if any clipper can dig to our south and produce a coastal low, much heavier snows would be possible. Just something to keep an eye on!
The only graphic I will include today is the GFS' depiction of the low. This is a good map, because it conveys everything I already wrote about: from the strength of the storm to the moisture setup, to precip types, to the mesolow. Pay attn to all these features and hopefully we'll have everything resolved in the coming shifts.
Currently: Pac High press in WV, w/warm front into NNE, so a pleasantly warm day across the area.
Tonight: W/cloud cover and no real cold air to speak of (yet), temps will be close to guidance in the fcst, basically within a few deg of freezing everywhere in the state.
Tomorrow: Cold air begins to rush in. I went way below temp guidance, as I just can't see any reason that temps would rise as much as it shows. Temps rebound a few deg, to the mid to upper 30s, before they begin to fall again. Winds will pick up by midday, and gust to 40-45 MPH as the gradient between an ocean storm and the arriving cold air mass sharpens. It is not impossible for a wind advisory to be needed, esp for E CT.
Tomorrow Night/Sat: The core of the Arctic air mass moves in. Winds will diminish after midnight tomorrow night, but it will still be breezy thru the day Sat. Except maybe if we can downslope along I 91, the entire state will stay below 20 degrees throughout the day! I went very close to guidance on temps, except a bit warmer in the CT Valley.
Long Term: The long term concern revolves around a major storm system for later Sun into Mon.
So on Sun, clouds increase, but I'll keep the day period dry, as precip should not arrive until well after dark. I kept temps close to guidance. On one hand, you have strong warm air advection. On the other hand, you have increasing clouds and not much solar contribution. So figuring these two are a wash= follow guidance temps. Highs should be somewhere around 30 degrees across the state.
Precip should arrive by midnight Sunday night. I think we start as snow everywhere, except maybe the extreme SE coast. We will probably change to rain, or at least non-snow everywhere, fairly quickly as warm air races in w/the low tracking to our west. In general, advisory level snows are likely for most places, except the extreme SE coast, where near zero is likely.
Now, part of the problem will be if we go directly from snow to rain or if there are other precipitation types in between. I am not going to fcst any freezing rain at all. To get freezing rain in this part of the world, you generally need to have a mechanism to lock cold air in at the surface, but completely scour it out of the upper levels. That is not the case here. I was originally thinking that this would be pretty straightforward just snow to rain, but some of the new 12Z guidance has thrown me a bit of a curveball, in that they are developing a 2ndary "mesolow" off the coast of NJ. If this is true, sfc winds would back around more to a NE direction and lock in more cold air. However, most of the damage aloft would be done and this could create an extended period of sleet. This is a relatively new feature on the modeling, so it bears watching for potential adjustments or if it exists at all.
The next problem is wind. Just based on pressure gradient alone, winds should easily gust to 50 MPH at times everywhere. Some models have been producing a "sting jet" feature, which, if real, would produce wind gusts up to 70 MPH for a time Mon morn. Since we're still a little ways out, I have included gusts to 50 MPH for now, but no higher. When we see if the sting jet feature is real and can nail it down, we can bump the fcst up if necessary. On the back side of the low, later Mon, winds should gust to 40 MPH or so. This is the "easy" part of the wind fcst, as winds are much easier to fcst on the back side of storms in this part of the world.
Flooding should not be a major issue. Total QPF is 1-1.25", w/maybe some higher amounts. Ordinarily, on frozen ground, this could present flooding issues. However, we have fairly dry antecedent conditions, so we should be OK. Nuisance urban flooding is possible.
Flash freeze could be a concern later Mon, as cold air funnels in. It will be a race between temps getting back to freezing and winds drying out the ground. Later crews can have a look at that and issue any statements as necessary.
As far as temps, the high temps I have are close to guidance, w/some tweaks here and there and generally in the low 40s. It should be noted that these highs occur Mon morn, w/temps falling thru the day after that.
For Tue, a fair, but chilly day is in store. Guidance temps look very good and are generally accepted. High temps should be 30-35 degrees. Winds will still be up behind the departing storm and could gust to 35 MPH at times.
For Wed, a clipper system will pass by to the north. This could bring a brief snow or sleet shower w/it, esp to N CT. I went fairly close to guidance temps, w/some adjustments here and there. Look for highs generally in the mid to upper 30s.
For Thu, strong cold air advection develops behind the clipper system. For this reason, and w/models typical day 5 and beyond biases at resolving changing air masses, I went quite a bit below guidance temps. Look for highs near 30 degrees across the state.
In the long range, look for a continuation of a cold to very cold pattern w/ample storm opportunities. Right now, most of the storms look to be of the clipper variety, which usually deliver light snow and reinforce the cold air. However, if any clipper can dig to our south and produce a coastal low, much heavier snows would be possible. Just something to keep an eye on!
The only graphic I will include today is the GFS' depiction of the low. This is a good map, because it conveys everything I already wrote about: from the strength of the storm to the moisture setup, to precip types, to the mesolow. Pay attn to all these features and hopefully we'll have everything resolved in the coming shifts.
That's all for now! See you next week!
-GP!
-GP!
