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...COMPLEX FORECAST THROUGH THE PERIOD, WITH LOTS OF SYSTEMS TO TRACK...

4/30/2020

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Disc: We have a parade of systems moving thru in the next week or so, and none of them, even today's, which is a short term concern, is not very clear cut.

Currently: Low pressure is over NE IN.  A cold front, with cold occlusion, extends from the low down thru Central PA.  A warm front was draped from Central PA thru SNJ.  High pressure was located off Nova Scotia.  Most of CT is dry right now, but a few showers are clipping extreme SW CT.

Rest of today: Adding a rest of today period to cover the next few hours.  Other than showers clipping the far SW, most of the daylight hrs should be relatively dry.  As far as temps, guidance is in pretty good agreement.  Expect highs in the mid to upper 50s.

Tonight: A couple of really big questions remain as to how much rain falls.  The rain along the cold front is training along the front.  The problem is, a lot of times when the rain bands make such slow progess eastward, they can essentially "rain themselves out" over one area.  The GFS has a strange, but plausible, evolution, where it shows the rain falling apart as it heads towards CT, then picking up Atlc moisture and re-energizing over E CT.  The NBM guidance does not really agree with this evolution, and has much more uniform totals, around an inch and a half for the entire state, with just a slow decay from W to E.   This evolution kind of makes more sense.  Either way, it will rain, heavy at times, mainly in the 2nd part of the night.  I'll keep t-storms out of tonight's forecast, as that element of the storm will definitely lose steam before getting here.  Winds should stay fairly gusty until dawn, so keep that in the fcst all night, with gusts to at least 30 MPH, possibly higher in heavier showers.  As for temps, I'll go way above guidance and keep temps steady thru the night.   There is no fropa during the night, and strong S winds, so no reason for temps to drop much.  Expect temps to drop to around 50 with the onset of rain and then basically sit there.

Tomorrow: After some morning sun, showers and t-storms will redevelop.  However, the main focus will be closer to the stalled low pressure system, i.e. west of the Hudson River.  I still feel that some showers and storms will make it into CT, but I am having a hard time believing any get into Srn New London/Srn Middlesex Counties, so no showers will be included there.  The further west, and away from water you go, the stronger and more widespread these storms will be.  So I will include a chance of strong storms in the NW Hills (i.e. Nrn Fairfield and Litchfield).  For the rest of the state, scattered showers and storms.  As for temps, guidance is in excellent agreement, and I see no benefit in trying to make it any better.  So highs should be 60 to 65 degrees.

Tomorrow Night/Sat: All this wx might be worth it if we get a nice weekend, and it appears a beautiful weekend is in store.  For Saturday, expect plenty of sun, and pleasant temps.  Guidance is in good agreement, so no major changes planned.  Highs should be around 60 degrees, but the coolest areas will be along the S Coast, with a developing afternoon sea breeze.

Big questions revolve around Sunday's forecast.  A developing mesoscale convective system (MCS) could have big impacts on the fcst for Sun.  The GFS, first off, is much faster than everything, and also weaker.  Weaker, in a sense, would be easier to predict, for two reasons.  First, we wouldn't have convection ruining model fcsts.  Secondly, it would be more spread out, so the entire area would get a general light rain.  The ECMWF, on the other hand, is much stronger with this feature, and much slower.  The GFS would occur Sun aftn, while the ECMWF would be more like early Mon morn.  The ECMWF centers the action around NYC, which keeps anyone N of the Merritt Pkwy dry.  A solution like the ECMWF would mean 1-3" of rain centered around a 40-mile wide area, with nothing N or S of there.  Because of all this uncertainty, and the possibility for more sea breezes, I went several degrees below guidance on Sunday.  There is just too much uncertainty to buy really warm temps yet.  So Sun's temps for now are being kept the same as Sat: 60-65.

Not much going on for Mon or Tues.  Both days should be pleasant, with reasonable temps,a bit below normal.  For both days, guidance has been accepted pretty much as is, as there's usually no reason to deviate too much on those types of days, esp when said days are 4 and 5 days away.  A sneaky little cold front moves thru Mon nite.  It is moisture-starved, so don't expect any rain with it.  But it will be about 5 deg cooler on Tues.  So highs should be in the mid 60s Monday and near 60 Tuesday.  Both days should be 3 to 5 degs colder in the NW Hills.

The next potential wx problem is Weds.  A weak coastal low scoots to our S.  Although the actual low pressure center appears fairly weak, there could be a good amt of overrunning moisture with it.  In addition, models have been trending N with it.  Obviously, as of now, the S coast is most favored.  However, I wouldn't be surprised if this trends into an entire state rainfall.  I went well below NBM temps, because of the trend N with the rain and the fact that this is not yet reflected in NBM guidance.  This yields quite chilly temps for the time of year, with highs of only 50-55 expected! 

Skies clear out Thurs.  There is very strong cold air advection, relative to the time of year.  For that reason, I undercut guidance temps by a couple degrees.  Highs should only be in the mid to upper 50s, despite sun! 

Looks like chilly wx continues right into the day 6-10 period.  There could even be a few sleet/graupel showers over Mother's Day weekend, esp in the NW hills. 

Now, let's take a graphic look at some systems slated to affect our area.  I'll show tonight's rain and Sunday's potential.  I'll post them as depicted by the GFS.   Keep in mind, esp for the Sun night potential, that other guidance is still very different.  Here is tonight's system.  The wild card is all that moisture out in E PA and how exactly it affects our area.

​
Picture
Next, here is the Sunday potential.  Keep in mind, this could end up N or S of where it is depicted.  And most models do have heavier precip in the core of it.  
Picture
Anyway, that's all for now... it was probably too much! Take care and stay safe!

​-GP!
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Forecaster Discussion--4/26/20

4/26/2020

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Good morning from SCW!

I hope you and your family are all happy and healthy on this Sunday morning. We've seen quite a pattern shift the past few weeks, going from a very warm winter to very cold spring. This long April is coming to an end, but the pattern is not. We will likely enter May with colder than normal temperatures and an active pattern. Although the measurable snow is likely done, the rain is not. Let's dive in. 
Picture
A recap of the temperature departure for the month of April. After a torch January, February, and March, April has been "cold". 

Sunday-Monday
Clouds and rain showers moved in overnight in advance of a slow moving area of low pressure, and although there are more spotty showers currently, over the course of the day we will see more widespread rain. Unlike yesterday, today is much colder and wet throughout. 

It's not much different on Monday, when the storm is expected to be offshore but still bring showers and colder than normal conditions to the state. Tomorrow looks like showers will be more spotty in nature, but for those that need to head out, it is an umbrella day. 
Picture
Tuesday-Wednesday
The storm is slow to depart, but after some possible early showers on Tuesday things should clear out as a weak area of high pressure builds in. Tuesday is looking cooler than normal (theme of the week) but we should see decreasing clouds. Wednesday is a tricky day. I think the next storm system will be a bit delayed, but at the very least, I think we will see increasing clouds and an increasing chance of showers the further into the day we go. It doesn't not look terribly wet, but I will introduce some low chances for showers. 

Thursday-Friday
More rain. Another low pressure system will approach the region and slowly move along, bringing rain and breezy conditions on Thursday and a lesser chance of showers on Friday. Temperatures look to be slightly warmer than the start of the week, but we will still be below normal. It seems the pattern is rinse and repeat! 
Picture
The Weekend
Perhaps we have some light by the end of the week? As the latest storm departs, it looks like we may get a bit of a reprieve from the cool and wet pattern. Another area of high pressure may build in, bringing us a period of warmer and dry conditions, especially on Sunday. For now, I'll take the optimistic view. The overall trend is clear, however. Colder than normal conditions are likely to remain into May. 
Picture
Climate Prediction Center (CPC) temperature outlook looking into early May. The probabilities of colder than normal conditions are high. 

The Dailies
Sunday: Mostly cloudy with rain. Highs in the upper 40s to low 50s. Chance of rain 100%. 

Monday: Mostly cloudy with rain showers. Highs in the mid to upper 40s. Chance of rain 70%. 

Tuesday: Showers possible early with decreasing clouds during the day. Highs in the low to mid 50s. Chance of rain early 20%. 

Wednesday: Partly sunny early with increasing clouds and showers by late. Highs in the mid to upper 50s. Chance of rain late 20%.

Thursday: Mostly cloudy with rain. Breezy. Highs in the mid to upper 50s. Chance of rain 70%. 

Friday: Mostly cloudy with rain showers. Breezy. Highs in the upper 50s to low 60s. Chance of rain 50%. 

Saturday: Decreasing clouds. Highs in the upper 50s. 

A​s always, please like, share, and interact with us on our social media--on Facebook to share our discussions, and follow us on Twitter @southernctwx to retweet our posts. Hit the buttons below to join.

Thank you for reading SCW. 

-DB​ 
Follow @SouthernCTWX
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...VERY ACTIVE WEATHER PATTERN TO CONTINUE...

4/23/2020

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This will be more brief than normal, due to being pressed for time.  It may still have to be longer than I intended, because of the active nature of the wx pattern.  I am also working with a depleted toolbox today, as MOS has not updated in three days, and my go-to radar is down, but such is life.

Currently: High pressure over central NYS shielding the area from rain, for now.  A stationary front draped from the Delmarva to Cleveland approaches later.  In addition, two lows, one near Des Moines and the other over SE MO will approach the area.  The Srn low becomes the dominant low, keeping the warm front S of the area.

Tonight: Rain spreads in from SW to NE.  Generally rain arrives mid-evening SW to around midnite NE.  Low temps should generally be in the low 40s.  There shouldn't be much thermal variation, w/dense cloud cover and precip, and no fronts nearby.

Tomorrow: A nice, gloomy, rainy day, if that's what you like.  If not, you can just think that it can't get much worse! Models have not been consistent on timing, but it should end during the evening hours.  It may actually linger longer in W sections of the state, with ULL passing overhead.  Tomorrow will be chilly, if not downright cold for this time of year.  Temps will only rise a couple degrees from the morning lows!

Tomorrow Night/Sat: After the rain pulls out, we sneak in a brief period of dry wx.  Although Sat should be gray and dreary, at least it won't rain.  Look for highs in the mid 50s or so.

Longer Term: The long term disco focuses on two rain events- one centered on Sunday and the other on Wednesday.  Tuesday is probably the best day of the long term, at least out to day 7 or 8.

Sunday: Low pressure will track very close to the area and then stall/decay near the area.  What this means for us in terms of sensible wx is rain arriving before dawn on Sunday.  Timing individual waves of pcpn this far out can prove to be futile, but more futile is not making an attempt at all.  It appears we'll get a slug of rain Sun morn, then a break, then another shot of rain Sun night, then another break overnight, with yet another shot of rain Monday morning.  Showers then linger thru much of the day Mon.  It will be a chilly rain, with highs only near 50 Sun and 40-45 Mon! Right now, it is not in the fcst, but it is not impossible for a few sleet pellets or snowflakes to mix in at the highest elevs early Mon morning, and again Mon evening, during the coldest parts of the day!

On Tuesday, we may actually see a bright orb in the sky for a few hours.  Please do not stare at it, as it has been known to cause eye damage.  This orb is known as the sun.  Tuesday will actually be a fairly nice day, with highs in the mid to upper 50s.

Rain from the next system should arrive Tuesday night after midnight.  At this time, Wed appears to be quite a washout, possibly even featuring strong t-storms W of I 91 later in the day.  Highs Wed should be 50-55.

A return to more fair wx is likely on Thursday, though an aftn shower cannot be completely ruled out.  Temps remain cool, in the 50-55 deg range.

Anyway, that's it for me... I have a hectic schedule today and I am running late! Take care and stay safe!

-GP!
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Late Season Snow Friday Night?

4/16/2020

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​Good evening from SCW,
 
If the times we live in aren’t strange enough, Mother Nature decided to throw us a curveball and bring a (hopefully) final shot of winter to parts of the state tomorrow evening. With a strong trough dragging down cold air from the north, along with some forcing and atmospheric lift, the table is set for a quick thump of heavy, wet snow across portions of the state. That said, any snow at this point in the calendar is marginal, and this setup especially so. Let’s take a look.
 
The key variables here are how far north the system pushes and the strength of the precipitation it brings with it. The further north the system, the more warm air gets pulled into our area, and the less snow we see. However, that can be countered to some extent by strong precipitation rates; most of the column is cold enough for snow, so if we get heavy snow just off the surface, dynamic cooling will take over and cool the bottom of the column enough for snow to the surface. Elevation will be just as if not more important than latitude in determining who sees significant snow.
 
Here’s a look at the simulated radars from the 3km NAM and GFS for 2 AM Saturday morning. These don’t quite tell the whole story here given that the situation is so marginal, and I’d probably expect a solution a little colder than depicted here if one were to verify perfectly. However, they do a good job at illustrating how relatively small ticks in the guidance can lead to a significant difference in outcomes. The GFS is the warm outlier here, the NAM is fairly close to the consensus, while the Euro (not shown) is the coldest of the guidance.
Total QPF on the guidance is somewhere between a half and two thirds of an inch for most of the state. If northern elevated areas are able to hold onto all snow, there’s a chance for warning criteria amounts (6”+), however, I think advisory criteria (3-6”) is far more realistic for those areas. For the rest of the state, I’m not confident in anything more than a wet inch or two for northern areas (a lot of “white rain”, i.e. snow that fails to accumulate, is a real possibility), and I think most southern areas will be plain rain, with perhaps a slushy coating of snow mixed in. That said, it would only take a small shift colder to make this a more meaningful event for many; the models being one degree too warm here would bring several inches of snow to most areas away from the shoreline (which I think is cooked regardless here). The trend has been to go ever so slightly warmer on the last couple of runs, hence why I’m a bit less bullish on that small shift colder happening, but there is still a whole day before game time and it’s not out of the realm of possibility that we see shift colder.
 
Unfortunately I don’t have the map software on this computer, so I can’t visualize it, but I’m going with 3-6” of snow in the hills, 1-3” for northern areas (roughly the northern four counties, though this will be somewhat elevation dependent), and nothing to a slushy inch elsewhere. Should we see a last-second tick colder, I’ll be comfortable taking these numbers up a bit, and I do think there’s the potential for that to occur, but confidence isn’t high enough yet to go for higher totals.

As far as timing goes, expect precipitation to move in around sunset or just after in western areas and quickly spread across the state. I think most precip will be gone by mid-morning (earlier south and west), but a few showers could linger into Saturday afternoon.
 
I think the main impact will be slick roads in elevated areas; if you’re planning on essential travel Friday evening and roads are bad in your area, please take it slow and think about if you really need to go out or if it can wait until Saturday. Our first responders have enough to worry about right now besides dealing with snow related car accidents. Otherwise, there’s a risk of heavy wet snow causing power outages in the elevated interior if totals near warning criteria do verify, that said, I think they will be fairly isolated in scope.
 
For the rest of your weekend, expect cool and raw conditions for most of Saturday, with temps only staying in the 40s. Sunday is clearly the pick of the weekend, with temps in the 50s to lower 60s and sunny skies, so we should naturally take care of any lingering snow by the end of the weekend.
 
I’ll be back with an update tomorrow afternoon if it’s needed, otherwise, enjoy the snow, stay safe, and thank you for trusting SCW.
-SA
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High Wind Watch for all of Connecticut in anticipation of a significant wind event on Monday...

4/12/2020

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Good afternoon and Happy Easter from SCW. 

Our Easter Sunday follows the path that Saturday took. What a beautiful weekend! There should be no weather issues today, but the main story for the week ahead is tomorrow. This discussion, while covering the entire week, will focus heavily on Monday. 

A big storm is taking shape in the southeast today, where a severe weather outbreak is just beginning. That storm will strengthen and move toward the Great Lakes region. For us, that means rain and windy conditions tomorrow. 

A High Wind Watch has been issued for the entire state, and I expect for that watch to become a warning at some point as the guidance and overall setup illustrates real potential for a significant wind event tomorrow. 
Picture
Monday
Tomorrow is an SCW Period of Interest. The overall setup is fairly straightforward. The big storm developing down south will quickly intensify and move northeastward. While the surface low will end up well to our west, we are looking at a very impressive setup for widespread wind and heavy rain. In addition to a deep low, we will see a strong low and mid level jet center itself right over our part of New England. That means that in the column of air above us, there will be exceptionally strong winds. The key question is whether those winds will "mix" down to the surface. The guidance seems to think yes, and I am inclined to agree. 

The next two images are ones we don't usually share, but illustrate the potential quite well. The first, is the latest GFS depiction of winds at 925mb tomorrow afternoon. It is important to note that 925mb is usually around 2,500 feet above the ground level. That's high up, but not that far when we're talking weather. 
Picture
There's a lot happening in this image, but I want you to focus on Connecticut. Essentially, what we see here is that there is a streak of strong winds aloft. This shows us that we're working with damaging winds off the surface.

All of this wind will not mix down to the surface. What matters here is that even if you do a reduction of the strongest wind gusts, we're looking at higher end wind gusts across much of the state and especially in southern Connecticut. But, there is a caveat. 
Picture
Above is an averaged sounding around the Hartford area tomorrow afternoon. Note on the right of the big box the wind barbs. It is not terribly windy at the very bottom (near the surface) but it doesn't take much height for winds to pick up quite a lot. This means that we're looking at more of a wind gust event rather than a sustained wind event. Note the temperature in red.

If we have temperatures lower than expected tomorrow (50s), that would limit the amount of mixing that happens. That would reduce, but not eliminate, the wind threat. If we somehow end up much warmer however (upper 60s to low 70s), the high end wind gust potential would be realized. I think we end up somewhere in the middle, with temperatures in the lower to mid 60s. 

Rain is the other threat here, but is a lower risk. We should see moderate to heavy rain at different periods during the day resulting in 1-2 inches of rain. That may cause some basement flooding issues in areas that flood frequently. The flash flooding risk is relatively low. 
Picture
Picture
Top image, high resolution image of the 12z NAM showing high wind gusts in knots. That translates to 55-65mph gusts. Bottom image is the 12z GFS depiction of the storm progression. 

That was the long version, here is the short of it: 

Monday has the potential to bring a moderate to high end wind gust event for Connecticut

  • Rain will begin overnight and will be moderate to heavy at times statewide during the day Monday.
  • 1-2 inches of rain is expected.
  • Thunderstorms are possible, but severe thunderstorms are currently unlikely. 
  • I expect widespread strong to damaging wind gusts, particularly during the afternoon hours 
    • ​For all areas away from the immediate shoreline, we can expect the highest wind gusts to fall between 55-65mph.
      • The highest gusts are likely to occur in elevated areas of central and eastern CT, as well as along the CT River Valley due to the southerly wind component.
      • Lower wind potential exists in Litchfield County. 
    • Along the immediate shoreline, we can expect the highest wind gusts to fall between 60-70mph.
      • We cannot rule out the immediate coastline of SE CT seeing wind gusts slightly higher. 
  • ​With the wind potential tomorrow, we expect scattered to widespread power outages. Two mitigating factors are that we do not have leaves on all the trees yet, and this does not seem to be a long duration event. 
    • ​Interior CT: scattered power outages.
    • Immediate shoreline: scattered power outages with smaller pockets of widespread power outages, especially in SE CT. 

There's still time for us to watch the progression of this event, so stay tuned. You certainly want to bring inside your loose furniture/items and prepare your basement if it floods during heavy rain. We will be here to provide frequent updates tomorrow both on our Facebook and Twitter (@southernctwx) pages. 
Tuesday-Friday
Tuesday is looking like a nice day. The storm will depart late Monday, and things will clear out behind the cold front. Unfortunately, we see showers and cloudy conditions return by Wednesday as a disturbance approaches. A washout is not expected. Thursday looks like another clear day, and by Friday we should see more clouds approach late as we see our next storm system approach. 
Picture
Saturday-Sunday
The weekend is looking decent, but a little unsettled at the start. Another area of low pressure will traverse the region and should bring us some rain early on Saturday. We should be able to clear out fairly quickly, and next Sunday looks nice. Let's watch next weekend a bit. There may be some mixed precipitation with that one if cold enough air advects in, but right now, I'm thinking rain. 

The Dailies
Monday: SCW Period of Interest. Heavy rain and strong winds. Highs in the low to mid 60s. Chance of rain 100%. 

Tuesday: Mostly sunny. Highs in the upper 50s. 

Wednesday: Mostly cloudy with a chance of showers. Highs in the upper 40s to low 50s. Chance of rain 30%. 

Thursday: Mostly sunny early with increasing clouds and a chance of rain showers late. Highs in upper 40s to low 50s. Chance of rain 20%. 

Friday: Mostly sunny early with increasing clouds and rain late. Highs in the mid to upper 40s. Chance of rain 50%. 

Saturday: Rain early with clearing conditions during the day. Highs in the upper 40s to low 50s. Chance of rain 40%. 

Sunday: Mostly sunny and warmer. Highs in the mid 50s. 

A​s always, please like, share, and interact with us on our social media--on Facebook to share our discussions, and follow us on Twitter @southernctwx to retweet our posts. Hit the buttons below to join.

Thank you for reading SCW. 

-DB​ 
Follow @SouthernCTWX
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