Disc: The pattern that has been ongoing since about 8 weeks ago looks to just roll on through at least the next 10 days- frequent unsettled weather with highly variable temperatures and frequent bouts of "onshore flow".
Currently: The frontal boundary (which we could almost analyze in the same spot every day) extends from SW MI down to the Srn Delmarva. An associated low pressure system was near Green Bay. This has placed the state in a maritime, cool flow.
Tonight: Lots of clouds, but not much in the way of precipitation. Models (and radar) do not particularly show drizzle well. But tonight does not appear to be a "drizzly" night because right now the winds are up a bit. If winds calm down, the south coast could see drizzle and fog. This is possible in Srn Fairfield County after midnight, but for now I think it will be too patchy to really include in the forecast. As for temperatures, we're probably at our low temperatures right now, with temperatures staying steady or slowly rising through the night. Two things should be noted, however. First, models tend to rush warm frontal passages. And secondly, we are currently a few degrees colder than any model currently has. So basically for lows, just go with whatever temperature it is right now.
Tomorrow: Tomorrow appears like the classic type of spring day where you get a period of steady rain in the morning, followed by some clearing, and then a line of showers and thunderstorms in the afternoon. The biggest question on a day like that is how much, if any clearing, occurs. This affects the strength and coverage of showers and thunderstorms with the cold frontal passage and of course, also affects temperatures. I really do not have a whole lot of confidence in temperatures tomorrow. However, the best forecast for tomorrow is to go a few degrees under guidance, since models are all showing "OV" (overcast skies) in the MOS. This implies very little, if any, clearing. If this is true, high temperatures stay in the 60-65 degree range, coolest along the south coast. In addition, the morning "warm frontal rains" would be more likely in the morning. As for afternoon convection, we'd be likely to have to rely on a weakening line heading from the west with the cold frontal passage. This should weaken rapidly as it heads into a very stable maritime air mass. So I think coastal and eastern locations may just see a passing shower with the cold front. Over western and especially interior sections, scattered thunderstorms may survive, especially since the air mass will be a bit warmer.
Tomorrow Night/Saturday: Probably the easiest part of the forecast. We clear out behind the front and Saturday turns out to be a very nice day. It will still be a bit chilly for the time of year. I'll go close to the cooler NAM MOS, given a fairly strong NW (cold advection) flow. Highs should be in the lower 60s.
Long Term (Mother's Day and early next week): A complex storm system affects the region. There are big-time model differences, with the GFS being dry for Sunday and focusing the storm on Mon-Tue. The ECMWF is wetter Sunday. An alternative solution, which I am favoring at this time, is that Sunday may be "mostly" dry during the day, but be dank and cloudy with areas of light rain and drizzle, then a steadier heavier rain developing later Sunday evening and continuing all day Monday. I also tend to like the GFS' idea of continuing, at the very least, showery rains into Tuesday, since the coastal may have not pulled all the way out yet, and even if it does, there will be an upper level low around to continue at least showers. So, having said all that, expect the bulk of the rain to fall during the day on Monday. But Sunday will likely be drizzly and dreary. Then expect lingering showers on Tuesday. It should also be noted that the freezing level is unseasonably low for the time of year on Tuesday, only around 800 MB. With a freezing level that low, it is not even out of the question to see some small hail or snow pellets with any heavier showers, especially over the NW Hills! As for temperatures in the Sun-Tue period, I'll go a couple degrees below guidance on Sunday and Monday. Then on Tuesday, soundings show convective temperatures at levels more typical of late March. This indicates to me that showers will be plentiful. With cold air aloft (34F at 850!), any showers will cause temperatures to really drop. So I have gone six to eight degrees below guidance for Tuesday! This yields highs of 60-65 Sunday, 50-55 Monday and struggling to reach 50 Tuesday!
The weather calms down a bit after Tuesday. Wednesday should be a pleasant, albeit chilly, day for the time of year. The next frontal system should bring at least the threat for a few showers by later Thursday. With lingering cool 850s, I've opted to go a couple degrees below guidance Wednesday. Convective temps are still pretty low. This does not mean we'll get storms, but lots of puffy cumulus should form, which would put a cap on high temps. With increasing "synoptic scale" clouds on Thursday, I've gone 3-5 degrees below guidance. So expect high temperatures of 60 to 65 both days. Thursday could turn out a degree or two warmer than I am forecasting if clouds hold off a bit longer.
Looking into the long range, the GFS-based guidance really wants to warm us up to summertime heat for at least a few days, perhaps a bit longer than that, in the day 10-15 time frame. The ECMWF based products show no such thing. Given a few facts, a) we've seen no such pattern yet, b) models tend to rush pattern changes (with the GFS-based guidance being a worse offender than the ECMWF), and c) it's still way out in time, I tend to caution jumping on this type of solution yet. It should also be noted that even if the GFS guidance did verify, the hot weather would appear to be very transitory in nature.
Now, let's examine some of the systems slated to affect our area in graphical format. First, let's look at tomorrow morning's warm frontal rains (which I think will be the bigger "show" in CT). This map, valid midday tomorrow, shows steady light rain over the entire state.
Currently: The frontal boundary (which we could almost analyze in the same spot every day) extends from SW MI down to the Srn Delmarva. An associated low pressure system was near Green Bay. This has placed the state in a maritime, cool flow.
Tonight: Lots of clouds, but not much in the way of precipitation. Models (and radar) do not particularly show drizzle well. But tonight does not appear to be a "drizzly" night because right now the winds are up a bit. If winds calm down, the south coast could see drizzle and fog. This is possible in Srn Fairfield County after midnight, but for now I think it will be too patchy to really include in the forecast. As for temperatures, we're probably at our low temperatures right now, with temperatures staying steady or slowly rising through the night. Two things should be noted, however. First, models tend to rush warm frontal passages. And secondly, we are currently a few degrees colder than any model currently has. So basically for lows, just go with whatever temperature it is right now.
Tomorrow: Tomorrow appears like the classic type of spring day where you get a period of steady rain in the morning, followed by some clearing, and then a line of showers and thunderstorms in the afternoon. The biggest question on a day like that is how much, if any clearing, occurs. This affects the strength and coverage of showers and thunderstorms with the cold frontal passage and of course, also affects temperatures. I really do not have a whole lot of confidence in temperatures tomorrow. However, the best forecast for tomorrow is to go a few degrees under guidance, since models are all showing "OV" (overcast skies) in the MOS. This implies very little, if any, clearing. If this is true, high temperatures stay in the 60-65 degree range, coolest along the south coast. In addition, the morning "warm frontal rains" would be more likely in the morning. As for afternoon convection, we'd be likely to have to rely on a weakening line heading from the west with the cold frontal passage. This should weaken rapidly as it heads into a very stable maritime air mass. So I think coastal and eastern locations may just see a passing shower with the cold front. Over western and especially interior sections, scattered thunderstorms may survive, especially since the air mass will be a bit warmer.
Tomorrow Night/Saturday: Probably the easiest part of the forecast. We clear out behind the front and Saturday turns out to be a very nice day. It will still be a bit chilly for the time of year. I'll go close to the cooler NAM MOS, given a fairly strong NW (cold advection) flow. Highs should be in the lower 60s.
Long Term (Mother's Day and early next week): A complex storm system affects the region. There are big-time model differences, with the GFS being dry for Sunday and focusing the storm on Mon-Tue. The ECMWF is wetter Sunday. An alternative solution, which I am favoring at this time, is that Sunday may be "mostly" dry during the day, but be dank and cloudy with areas of light rain and drizzle, then a steadier heavier rain developing later Sunday evening and continuing all day Monday. I also tend to like the GFS' idea of continuing, at the very least, showery rains into Tuesday, since the coastal may have not pulled all the way out yet, and even if it does, there will be an upper level low around to continue at least showers. So, having said all that, expect the bulk of the rain to fall during the day on Monday. But Sunday will likely be drizzly and dreary. Then expect lingering showers on Tuesday. It should also be noted that the freezing level is unseasonably low for the time of year on Tuesday, only around 800 MB. With a freezing level that low, it is not even out of the question to see some small hail or snow pellets with any heavier showers, especially over the NW Hills! As for temperatures in the Sun-Tue period, I'll go a couple degrees below guidance on Sunday and Monday. Then on Tuesday, soundings show convective temperatures at levels more typical of late March. This indicates to me that showers will be plentiful. With cold air aloft (34F at 850!), any showers will cause temperatures to really drop. So I have gone six to eight degrees below guidance for Tuesday! This yields highs of 60-65 Sunday, 50-55 Monday and struggling to reach 50 Tuesday!
The weather calms down a bit after Tuesday. Wednesday should be a pleasant, albeit chilly, day for the time of year. The next frontal system should bring at least the threat for a few showers by later Thursday. With lingering cool 850s, I've opted to go a couple degrees below guidance Wednesday. Convective temps are still pretty low. This does not mean we'll get storms, but lots of puffy cumulus should form, which would put a cap on high temps. With increasing "synoptic scale" clouds on Thursday, I've gone 3-5 degrees below guidance. So expect high temperatures of 60 to 65 both days. Thursday could turn out a degree or two warmer than I am forecasting if clouds hold off a bit longer.
Looking into the long range, the GFS-based guidance really wants to warm us up to summertime heat for at least a few days, perhaps a bit longer than that, in the day 10-15 time frame. The ECMWF based products show no such thing. Given a few facts, a) we've seen no such pattern yet, b) models tend to rush pattern changes (with the GFS-based guidance being a worse offender than the ECMWF), and c) it's still way out in time, I tend to caution jumping on this type of solution yet. It should also be noted that even if the GFS guidance did verify, the hot weather would appear to be very transitory in nature.
Now, let's examine some of the systems slated to affect our area in graphical format. First, let's look at tomorrow morning's warm frontal rains (which I think will be the bigger "show" in CT). This map, valid midday tomorrow, shows steady light rain over the entire state.
Next, let's look at the coastal low slated to affect the region from Sunday through Tuesday. You can see the low off the coast of NJ generating heavy precipitation, with one last batch poised to move through Monday night. You can also see the precipitation gathering from the upper level low over Western PA.
That's all for now! See you next week!
-GP!
-GP!
