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...A STORMIER PATTERN EVOLVING, BUT IT WON'T BE SUPER COLD...

12/23/2021

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As we get deeper into astronomical winter, the pattern does look to turn stormier, but it also does not look severely cold.  Still, there will probably be some opportunities for winter wx, esp N of the Merritt Pkwy.

Currently: High pressure over the Appalachians is in control of our wx today.  There is still a bit of a breeze, esp in E CT, from slowly departing low pressure over Nova Scotia.

Tonight: I went very close to guidance on temps, and actually a degree warmer here and there.  Clouds increase, winds shift to the S.  So w/weak warm air advection and overcast skies, temps don't drop fast.  A warm front approaches and should have a band of light snow with it.  Temps are cold enough everywhere for snow to fall and stick, but the problem is moisture content.  There may only be enough moisture to kick out a couple hundredths of liquid equivalent.  Therefore, any accums should be limited to a coating to less than a half inch.  As such, a snow map will not be needed for this event.  For low temps, I have mid to upper 20s for the state.

Tomorrow: I went below guidance on temps, as guidance appears to offer too much sun.  We'll prob be slow clearing out the morning clouds and as soon as they do, clouds from the next wave increase.  Don't forget, we have the lowest sun angle of the yr right now, so clouds don't break that easily.  Highs should generally be in the upper 30s.

Christmas Eve night and Christmas Day: Two waves will affect the area- the first centered on Christmas Eve night and Christmas morning, and the second centered on Christmas later in the afternoon and evening.  There could be a few hour break in between, which could complicate temps even more, but we'll largely stay cloudy.  I have likely POPS for the entire state, except the far E, where I have high-chance (50%) POPs Christmas morning, increasing to likely 70% later in the day.  The first wave may shred out and not do much at all in E CT.  I did not try to time any breaks.  The atmospheric column aloft is warm enough for all rain from both systems.  However, sheltered valleys in NW CT and NE CT may start as freezing rain Christmas Eve (Fri) night before transitioning to regular liquid rain.   Those areas will need to watch temps very closely.  The worst chances look to be in the NW valleys, as they'll also coincide w/better precp coverage.  I went significantly below guidance on temps, as guidance tries to allow for some sun midday, which I sincerely doubt will happen.  Highs generally near 40, except 40-45 in urban areas.

Long Term (Sun and beyond): Lots of waves to track in the long term, but cold air will be marginal at best.  First, for Sunday, not a bad day, but it will be windy.  There is modest cold air advection, and I think we're mostly cloudy, not mostly sunny as the NBM wishes, so I knocked off several degrees from temps.  Even so, it's still widespread low 40s.  Winds could gust to 35-40 MPH as drier air moves in.

Monday: A weak wave approaches, but largely falls apart before reaching the state.  In deference to the fact that the wave does exist and that some models do bring measurable, I have 30 POPs in for only W CT.  Precipitation type, if any, should be mainly snow, but due to warm surface temps and light precip, no accums are expected.  Even if this wave exercises its max potential on the area, nobody would see more than 1/2" of snow.  I went a few deg below temp guidance, due to some of the NBM members showing sun.  I can't see that happening even if the precip totally dissipates.  I did not go as low on temps as I might have, however, since we do have warm air advection and precip would be scattered at best.  Look for highs in the upper 30s.

Tuesday: i went a shade under temp guidance, since skies will generally be mostly cloudy.  It could be another one of those days where we have trouble scattering out the clouds before new clouds arrive.  Even so, temps still get to 40-45 statewide.

Wednesday: Gloomy day.  I don't really see any cold air damming or any sign of cold enough air, even for diurnal freezing rain, even in the coldest spots.   However, even a slight cooling could result in some patchy freezing rain, so the chance is not zero.   For now, I have only rain in the fcst.  Most rain will be light, but there could be steady, moderate rain in the morning.  By midday, forcing shuts off, so steady rain could end.  However, with low level moisture still available, drizzle is possible.  Being this far out, the most logical fcst is to just call for rain.  I went quite a bit below temp guidance.  Although this does not look like a freezing rain scenario, it also doesn't look like a scenario where a warm front just blasts through, since this is not a strong system.  Therefore, I expect more of a cold rain, with temps basically hovering near 40, maybe a few deg warmer in urban areas.

Thursday: Yet another wave in the train moves thru.  We could clear out in the morning for an hour or two, but I just find it hard to believe we get much sun any given day during this low sun angle time of yr.  W/the air mass even warmer than that of Wed, if I didn't put any frozen in on Wed, I certainly won't on Thu.  More chance to likely POPs for mainly light rain.  For continuity, I went pretty close to guidance, as I see warmer air slowly moving and an eroding low level cold.  So temps a deg or two warmer than those of Wed.

Longer Range: Storms and cold shots may both get stronger, according to today's long range guidance.  But at least for now, for snow geese out there, they never really coincide.  So you'll get a storm that tracks up to the west and brings rain, then it gets cold, then repeat cycle.  But it's still relatively early in winter and things can change.

I don't know if I really want to post storm graphics today, since nearly every day will offer a chance of measurable (but generally light) precip.  So I am going to post a map of the pattern and discuss it instead.
The map below actually shows an odd pattern- one that doesn't happen too much.  You have a fairly strong -NAO that actually connects with a weak SE ridge.  That almost never happens, but the reason it can happen is because of the deep trough out west, or a very neg PNA.  So in essence, what happens here is, temps are cooler than they'd be ordinarily with a SE ridge, but not nearly cold enough for sustained wintry wx.  In addition, storms tend to weaken as they approach the dual ridges.  As this evolves around New Years, you could probably see a stronger ridge connection over the east, with the trough over the west weakening and migrating a bit east and the ridge over Greenland also weakening.  That would promote stronger, warm storms, and also stronger cold shots between storms.  It is possible that as we hit mid-January, the pattern eventually flattens out into one that would transport more cold air nationwide and not necessarily favor huge storms, but at least favor light to moderate events, and perhaps a bit better wintry pattern overall.  But that is a LONG way from happening yet!

​


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Anyway, that's all for now! Have a Merry Christmas and Happy Holidays from SCTWX! See you next week!

​-GP!
Comments

...WARM PATTERN ABOUT TO EXIT STAGE RIGHT THIS WEEKEND...

12/16/2021

Comments

 
Today and tomorrow will be very warm.  After that, we'll see temperatures largely more normal for the season and then probably solidly below normal during the long range.

Currently: Warm front well thru the entire state.  We are under the influence of high pressure over NC, which really resembles a summertime Bermuda High.  The cold front that will begin to change our wx is way back over Indiana.

Tonight: I think guidance is way too warm.  Even though we're in a warm air mass, it's a dry one tonight, and we should be able to radiate very well.  Therefore, I've gone solidly colder than NBM guidance and used a "halfway to the dew point" approach, then blended that in with 30% temp guidance.  This yields low temps in the low 40s across the state.

Tomorrow: Temps are a bit tricky, because it really depends on when cold air advection begins to set in.  This time of yr, it is easier to accomplish than most of the yr.  Therefore, guidance could be a bit too warm, so I subtracted a little here and there.  Look for highs of 50-55.  It is possible we could see highs occur around late morn, and have a steep N-S temp gradient, but I didn't want to get too cute.

Tomorrow Night/Sat: The combo of cold air advection and a weak low traversing S PA into SNJ will produce a long duration light to moderate precip event.  Heaviest precip prob falls around midday, w/perhaps another burst late at night.  But even in between, light precip/drizzle will be falling.  

High pressure is located NE of the state, so the highest chance for frozen precip is going to be over E CT.  There is no southerly component to the wind at any level to speak of.  Therefore, I have done a few things w/the snow fcst for this event.  For SW CT, for now, I only have rain mixing with sleet at times and no appreciable accum.  For areas along I 84 and North I have mixed pcpn in the fcst, allowing for a period of mostly snow, w/light (1-2") accums.  I also have allowed for the possibility for up to 3" and a mainly snow event in Tolland and Windham counties.  Now the big ? is what to do with SE CT, i.e. New London and Middlesex counties.  Being that they are in E CT, there is some cold air drainage so even those areas could very well see a period of all snow.  It may be hard to get the immediate SE coast cold enough for accums, but I could see 1" falling in the interior portions of this county.

Now, what could change this fcst? I'll run the colder and warmer scenarios here, just to get better understanding.  If it's warmer than fcst, accums will be limited to elevations above 1000' N of 84 and prob be less than an inch.  If it's colder than fcst, then we may need to allow a couple more inches N of 84 and allow for up to 1" all the way to the S coast.  One thing that does appear fortunate right now, is that there is a cold layer around 900MB, which is colder than the sfc.  This pretty much eliminates any threat of freezing rain.  One other note, I do not see any possibility of anyone in the state getting more than 5" out of this storm.  That would be the absolute ceiling.  The storm just doesn't have tons of moisture to work with.  Also, w/relatively low rates, daytime precip, marginal temps, and previously warm ground, accums on roadways should be minimal.  However, I don't like to belabor this point, because even a patch of snow/ice on roads can cause problems.

Long Term (Sun and beyond): A pattern much more common for this time of yr sets in. 

Sunday: A morning shower leads to clearing skies.  Cold air advection will produce wind gusts of 35-40 MPH.  W/the combo of fresh cold air advection and the potential for some snowcover either over parts of the state or nearby, I have lowered guidance temps by quite a bit.  Look for highs only in the mid 30s.   W/the wind, it will feel like it's in the 20s all day!

Monday: Near neutral advection, much calmer winds.  Model guidance temps look fine.  In fact, I raised them a bit near I 91 corridor.  So expect highs generally near 40, except a patch of 40-45 along I 91.

Tuesday: I once again went near or slightly above consensus guidance.  High pressure briefly slides offshore, allowing for warmer temps for a day.  Look for highs in the mid to upper 40s.

Wednesday: Went just a smidge under guidance for two reasons.  First, we'll have weak, but fresh cold air advection.  Secondly, it will probably be cloudier than is indicated by the NBM.  I will explain that a bit further down.  But expect highs generally near 40, except 35 to 40 in the NW and NE corners of the state.

Thursday: Went close to guidance, if not a tad below.  Advection is nearly neutral.  Expect most highs near 40, w/allowance for a deg or two warmer near I 91.

It should be noted that there is a coastal storm progged by most modeling for the midweek period.  Most guidance does take this system harmlessly out to sea, but the trend has been to the NW and we have seen these things come NW before.   While not in the fcst right now, it would not surprise me if early next week we are tracking a coastal low.  Pcpn type should be snow for most, but mixed would be possible along the S coast.  Stay tuned! 

The long range looks cold and probably increasingly stormy.  It does appear winter is set to arrive in SNE!

Just one graphic today.  This map is valid Saturday around noon.  Notice how there is snow/mixed precip basically along and N of 84, and this has trended colder.


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Anyway, that's all for now! Happy tracking!

-GP!
Comments

...WARM PATTERN TO TAKE HOLD IN EARNEST, BUT IT LOOKS LIKE A BIG PATTERN CHANGE IS IN THE WORKS AROUND 10 DAYS FROM NOW...

12/9/2021

Comments

 
Enjoy the warm wx over the next 8-10 days (not including today, obviously), because a big change appears to be forming after that.

Currently: High pressure stretching from Quebec to VA is keeping the area high and dry (but cold) today.  A warm front over Michigan will move across the area overnight into tomorrow morning.

Tonight: W/clouds and developing warm air advection, temps won't drop a whole lot.  I went near guidance for the most part for temps, which is lows of 30-35.  The warm front may bring a quick snow shower, generally I 84 on north, but moisture is limited, so expecting very little or nothing in the way of accumulations.

Tomorrow: Sunny and pleasant.  Went below guidance, because I think it blasts the warm front thru too fast and tries to warm us up and clear us out too fast.  So highs of 40-45.


Tomorrow Night/Sat: Much warmer, near record warm temps possible Sat.  Temps will really surge ahead of our next cold front.  Temps prob don't drop much Fri night, then on Sat will really rise.  I have limited any rain chances to just a slight chance during the day on Sat.  It's possible a shower could pop up at any time ahead of the cold front, but the day period should largely be dry.  I've gone a bit under guidance w/temps, just to be on the conservative side, for example, in case there are more clouds than modeled.  But this still gives me highs near 60 everywhere, w/upper 50s on the S coast, due to Southerly onshore flow.  This could even still be too cool!

A shot of rain will accompany the cold frontal passage Sat night.  I have only mentioned a slight chance of t-storms, because it's rare to actually get lightning this time of yr.  But lightning or not, it could be one of those fropas that gets warned w/o lightning,  Along and behind the front, expect a period of 45-50 MPH wind gusts even outside of any convection!

Long Term (Sun and beyond): The long term looks generally pleasant, w/above norm temps.  It will be very windy early Sun behind the front.  Sun will also be much cooler, but it won't be all that cold, since the air is of Pacific origin.  I did go below guidance, due to cold air advection, and have highs of 40-45.  It is possible that the I 91 corridor downslopes their way to a few deg warmer.  Winds do diminish, but still gust to 30-35 the rest of the day.

For Mon, expect sunny and warmer wx.  I followed guidance pretty closely for temps, so I have highs around 50, with an area of low 50s along the I 91 corridor, again allowing for some downsloping.

For Tue, a carbon copy w/regards to both temps and sensible wx to Mon.  I followed guidance pretty closely for temps again, and adjusted them a bit in spots to match Mon's temps.

For Wed, I went a bit below guidance on temps, as various uncertainties begin to creep into the fcst, that would lower temps by a few deg, such as sea breezes and cloud cover increasing.  So I have the state basically painted in upper 40s.  Later crews can raise temps if needed.

For Thu, a weak wave passes thru in the morn.  Given fcst uncertainties this far out, I just have 30-40ish POPS statewide.  The air mass behind this wave is warmer than the air mass in front of it.  However, for now, I cut a few deg off guidance, just in case we're too fast w/the wave and clouds or rain linger later into the day.  Later crews can again raise temps a bit if needed.  For now, I have temps sim to Mon and Tue, if not a deg warmer in spots, but that may not yet be warm enough.

As we head into the longer range, it is appearing more and more likely that a large scale pattern change is going to develop a few days beyond the range of this fcst.  So enjoy the wx we have now, because changes will be coming!

There will only be one graphic today, and it will show Sat night's frontal passage.  There really isn't much going on this week! This map shows Sat night's fropa.  Take a look at how fast the temp will change behind it... this is indicative of a drastic frontal passage w/strong winds and maybe even convection!
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Anyway, that's all for now! See you next week!

​-GP!
Comments

... COLD PATTERN HANGS ON ONE MORE WEEK, BECOMES MORE UNSETTLED, CHANGES ARE AFOOT AFTER THAT...

12/2/2021

Comments

 
Disc: We'll stay cold for the next seven days or so, but after that, we flip to warm, probably for at least 10-20 days.  Also, it looks like the very dry pattern we had is ending.

Currently: Warm front has crossed the SW 1/2 of the state.  Cold front near the Great Lakes will move thru tonight

Tonight: There could be a brief sprinkle early w/the cold front, (maybe mixed w/sleet or snow far N), then skies clear and winds increase.  Due to pretty strong cold air advection, I have gone below temp guidance for lows.  Most lows should be 30-35 degrees.  Winds pick up by morning, and will be gusting 35-40 MPH thru the 1st part of tomorrow.

Tomorrow: Windy, esp early, and much colder.  Temp guidance does not look awful, but w/fresh cold air advection, I chopped just a bit off the guidance.  Look for highs generally in the low 40s.

Tomorrow Night/Sat: Yet another weak clipper in the flow approaches and brings a quick shot of precip (prob snow) to the area.  I am not expecting any accumulations, except maybe northern areas above 1000', where they might be able to squeeze more moisture out of the atmosphere.  The NBM does not pick up on this feature very well, so I chopped a few deg off temps.  Expect highs generally 40-45.

Long Term: Two systems affect us in the long range, the first on Mon, and the second on Wed.

First, for Sun, sunshine and a high pressure system pulling offshore should lead to moderating temps.  Look for highs in the upper 40s, except mid 40s in the NW and NE corners of the state.  Guidance was generally followed, w/some small regional adjustments.

A strong "Lakes Cutter" system will affect the area on Mon.  Since the antecedent air mass is not cold, I expect all areas to begin as rain.  It's too early to give exact timing, but it appears like there could be two distinct shots of rain w/this storm: one later Sunday night into early Mon morn w/the warm front, then one later Mon/Mon eve, w/the cold front.  Winds pick up and gust to 30 MPH during the day Mon out of the S.  I usually go below guidance during storms, but w/so much warm air moving in, I decided to follow guidance pretty closely, and go with upper 50s.  I did go below guidance along the S coast, with a S wind off the cool LI Sound.  There I have 50-55.

Temps crash Mon nite and it's not out of the question for precip to end as snow.  Models have been backing off on this, however.  I still wouldn't totally rule it out, esp for the NW and NE corners of the state.  Winds pick up behind the front out of the NW, w/frequent gusts 40-45 MPH later Mon into early Tue.   Wind advisories may be needed for that time period.

For Tue's temps, I went just a bit below guidance, as there is still some fresh cold air advection.  It's a cold day w/diminishing winds.  Look for highs around 40 degrees, prob staying in the upper 30s in the NW and NE corners of the state.

The next system affects the state Wed-Thu.  This could be a two-part system, where a secondary coastal forms.  It could also be a colder storm.  For now, models are pretty warm for snow.  However, the usual places, Litchfield, Tolland, and Windham, may be able to start frozen and accumulate some.  They may also be able to switch to snow when the secondary coastal takes over.   This is way out, so the fcst for now is a broad brush.  There could also be a break in the precip later Wed into early Thu, but I don't want to get too cute w/timing at this range.  I went below temp guidance for both days here, as there really doesn't appear to be a warm fropa this time.  I have near 40 pretty much all areas Wed, and low 40s Thu, but kept it cooler in the Northern areas, except BDL-HFD, and those areas are in the upper 30s, as they may transition back to snow.  Winds do not look overly strong w/this sys, so are not being mentioned.

The long range pattern does not look significantly cold.  It does look stormier than what we have seen, but it appears all/most of the precip should be in liquid form.  There is some hope we flip to colder after the 20th or so, but that is so far out, it is basically fantasy land.

Now, let's take a look at a couple graphics showing systems slated to affect the area.  I am not going into too much storm details w/these systems, since they're so far out in time and fairly complex.  However, it is important to note how much precip these systems will produce.  Nov was very dry across our state, w/just around 1" of precip the entire month.  These systems will combine for much more moisture, just between the two of them, than Nov had for the whole month!


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The last image includes both events, which exceeds precip for all of Nov!
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Anyway, that's all for now! See you next week!

-GP!
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