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Wednesday, August 31, 2016

Tropical Storm Hermine Taking Aim on Tri-State

My expectation was the upcoming holiday weekend would be mainly dry. Maybe some clouds and rough seas at worst, but as of tonight models suggest it is going to be much more than that. Latest models are pointing to a significant rain and wind event as Tropical Storm Hermine tracks up the east coast. Here is the latest probable path from the National Hurricane Center:



Before I talk about the potential impacts this storm may bring, I figured I will detail why the models made a dramatic shift west with the track. Ultimately, it comes down to the strength of Hermine which dictates its speed. A weaker storm typically moves faster while a stronger storm moves slower. 


Let's compare 500mb height anomalies between Monday's GFS against today's. The timestamp is valid for Friday evening. 

Monday 12z GFS (top) Vs. Wednesday 18z GFS (bottom) 




The glaring difference is Hermine is much stronger. In Monday's run, she was barely a depression over North Carolina whereas in today's run she is a Tropical Storm over South Carolina. The Atlantic Ridge is further west on the latest GFS, and the trough over the northwest Atlantic is weaker / faster. These realities are part of the reason why Hermine will track along or just off the coast rather than drift out to sea. 

The other reason - most important - why Hermine could track close to the coast is because the trough at the 250mb level captures Hermine and retrogrades her back west. The strong jet streak will bring about a dynamical aspect of the system that would allow strong winds to mix down to the lower levels, or surface, of the atmosphere. 

Some say when Hermine gets here she may not be a Tropical Storm. Maybe a sub-tropical or extratropical system. Honestly, who cares. Call it a Nor'easter if you want. But if the afternoon model runs come to fruition then expect lots of rain, high winds, and surge at the beaches. In my eyes this will be a Tropical Storm when it gets here due to the dynamics that will be at play. 


Check out this animation:

http://tropic.ssec.wisc.edu/real-time/mimic-tpw/natl/anim/latest72hrs.gif

This loop shows atmospheric moisture, or precipitable water. In the Gulf of Mexico we have Hermine and off the coast of North Carolina there is Tropical Depression 8 (look for the circular motions). The orange and red colors indicate a moist atmosphere. As Hermine tracks north, there is a good chance it is going to take this moist atmosphere and move it into our area. This would enhance rainfall amounts and cause added headache to those along the coast. This too will play part of the systems dynamics. 



A closer look at the 500mb level shows Hermine getting 'stuck' under a strong block to its north. The ridge you see in central Canada on the 500mb maps I posted above tracks east-southeast and traps Hermine under it. So between the 250mb trough and 500mb ridge, Hermine's effects will be felt for almost 24 hours. More in some places. 


The EURO is especially impressive with the wind and rain. 850mb winds on the EURO are near 80kts!! 




The GFS has 925mb winds (closer to the surface) near 70kts. Just further proof that the system will be fairly potent when it gets here. 




The Canadian models suggests rainfall could be anywhere from 3 to 6 inches all within a 24-hour period. That would cause extensive flooding, especially in flood prone zones. 

IMPACTS

1. There is still 3 important model suites to run before Hermine gets here. There is a chance models intensify Hermine more in the event they are downplaying the dynamics. I am impressed with the jet stream at the 250mb level. I think the GFS is too weak with the storm at the moment, and a blend between it and the EURO is not a bad forecast at this time. 

2. Rainfall is likely to be in the 3" range. The difference between 2-3" and 5-6" will depend on the exact track of the storm. Since we've been mainly dry the last 10 days getting a heavy dose of rain in a short period of time could bring flooding concerns to much of the state. 

3. Since there will be a retrograde back west, this is likely to enhance storm surge along the immediate coast. The NJ shore and southern shores of LI could ill-afford their beaches being destroyed or homes receiving property damage. Once the exact path of Hermine is nailed down, we'll have a better idea of the surge and how bad it may be. 

4. Wind is expected to be at least Tropical Storm strength for pretty much everyone in the Tri-State. Gusts could be as high as 65-70mph with sustained winds in the 50mph range. The combination of high winds and heavy rain could lead to power outages across the area. 

I'll have another update on Friday! 

Have a good night.

Best,

Francesco Paparatto 







Sunday, March 27, 2016

March 28, 2016 Mo Mo

I hope everyone had a nice Easter with their family and friends. We're starting Monday off on a dreary note. Rain should come to an end around Noon today. The rest of the week looks fairly mild with temps in the upper 50's to low 60's. By Thursday afternoon into early Friday, another round of rain is expected from a cold front. Less then 1 inch of rain is expected. 

Rain Thursday afternoon

Once the cold front passes through a rush of cold air will storm into the Northeast. Do not rule out a snow squall Saturday afternoon into the evening. This could possibly be our last cold blast of the season. Temperatures are expected to get down into the 20's (teens N&W) with high's only in the upper 30's to low 40's. 


The American and European Ensemble suites are in agreement the Polar Vortex will track southeast of the Hudson Bay and force a trough over our area. 


Notice how the ridge pops in the west and there are some higher heights over Greenland. This remains a transient pattern so the cold will not be long-lasting. I think by the time we get to Tuesday the 5th the cold will begin to moderate and temps will gradually warm up again. 

Temps Sunday morning (April 3rd) are only in the 20's and 30's across the region. 

Temps 2pm Monday (April 4th - Yankees Opening Day) will only be in the 40's. Bundle up if you're going to the game!! 


That is all I really have to report in today's Mo Mo. A couple rain shots this week, maybe a snow squall Saturday with an arctic blast, and back to warm temperatures by the middle of next week with more rain chances on the horizon. MY 2016 SUMMER OUTLOOK WILL BE OUT SOMETIME IN APRIL. Be on the lookout! 

Have a great day. 

Best,

Francesco Paparatto 
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Thursday, March 17, 2016

Come Fly With Me Through The World Of Model Mayhem

There are significant differences between the EURO and GFS models in regards to the Sunday into Monday storm. The EURO has a strong surface low tucked near the coast bringing over 12" of snow to the area, while the GFS scrapes the area with just a few snow showers. The caveat is the GFS Ensembles are closer to the coast and the EURO Ensembles are even more impressive and further west than the EURO OP. It would not be a big snowstorm without model disagreement! 



Here is a look at today's 12z EURO 500mb height anomalies valid late Saturday. This is a good look of how the pattern will set up. As explained yesterday, we will have a -NAO/+PNA to work with. The higher heights over and east of Greenland is a nice -NAO. Not classic but it's our best block all winter. The ridging in the west into the Arctic is a very impressive +PNA/-EPO. This is what will help drive the northern energy and arctic air into the northeast. The goal is to get a phase to occur between the northern and southern phases. As shown yesterday, we do not need a phase to get a big snowstorm since the southern energy is strong on its own, but I would feel comfortable knowing a phase will happen because it lessens the odds this storm goes out to sea like the GFS OP is trying to show. 


Today's EURO at 500mb is almost a replica of yesterday. There is no phase but the southern energy is stronger today, so the surface low is pulled closer to the coast and those west into PA get into the action. Notice how the northern energy is still over the Great Lakes but it's trying to dig quickly into the coast for a phase. 


Recall yesterday the EURO was showing a surface low around 991mb. Now it's closer to the coast and around 988mb. The EURO Ensembles are even more impressive. Some members are around or sub 980mb with the low so close to the coast that the Jersey Shore and Long Island see rain or mixing. 


The 200mb jet streaks and wind vectors suggest this storm has a clear path up the coast toward the Benchmark. It will be interesting to see how dynamical this system could get. If there is no phase, the storm may struggle trying to wrap colder air into its core so dynamic cooling would be difficult to achieve. This may bring mixing concerns to parts of the immediate coast, including NYC. Even though the EURO is not showing this, it's still worth noting soundings may be showing a warm layer somewhere. This is why it's critical we at least see a partial phase with the northern energy. 

The GFS is off the coast because it rushes the southern stream ahead of the northern stream and the vorticity never wraps itself into the trough. Everything looks a little fast and pretty strung out. It does not have support from its own ensembles nor other guidance such as the SREFS and GGEM. The only reason I am not completely discounting the GFS is because of the northern branch remaining disjointed from the southern one. However, the southern branch should be able to manage a storm at least near the coast given the -NAO/+PNA/-EPO. 

Tomorrow will be a critical day of model runs if you're a winter weather enthusiast. Either the EURO holds serve and regains its reputation as "king," or the GFS will out perform it once again like it did a few times this winter. At this moment, I am leaning in favor of the EURO and its Ensembles because I feel it handles -NAO type storms very well. and it has support from other guidance. Therefore, I am currently forecasting a 6 to 12" snowfall for the area beginning midday Sunday into the 1st half of Monday. The potential still exists for a Godzilla (12" or more). We'll see!

Enjoy the rest of your night. 

Best,

Francesco Paparatto
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Wednesday, March 16, 2016

Tracking A Spring Godzilla Between March 20th-21st

El Nino has dominated our winter pattern. Above normal temperatures with very few snow chances. Jonas was our big Roidzilla - a historic storm - but this season leaves winter weather lovers wanting more. After experiencing temperatures in the 80's last week I think it's safe to say most put this lackluster season to rest. Looking at the latest weather guidance I think it's fair to say Mother Nature has other plans. March may go out like a lion. 

Earlier in the month I noted the 2nd half of March may be on the cooler side. There were signs of the NAO going negative and the ridging returning to the western half of the U.S. According to latest guidance we are heading in that direction. These combinations in an El Nino flow are a recipe for big east coast storms to form. 



The NAO is definitely heading into a negative state. This is also shown on the 500mb height anomaly graphics which I will get to soon. This is important because not only is it just the 2nd time this season the NAO will go negative, but it's key to getting an east coast snowstorm happening. It will try to slow down the fast Pacific flow and give upper energies in the atmosphere a greater chance to phase. 


The EURO on Saturday morning shows a large Upper Level Low over the center of the country. Notice how the other ULL over New England is trying to exit stage right by moving north and east. This is critical. The greater the separation between these two ULL's, the higher the odds are of this possible Godzilla on Sunday coming to fruition. The reason being the eastern trough has room to amplify and the upper level vorticity gets wrapped in instead of stringing / shearing out like the GFS shows. As this ULL digs south, heights along the East Coast rise (Atlantic Ridge) which paves a path for this storm to track up the coast. 


By Sunday morning notice how the ULL that was over New England is out of the picture. In response, the Atlantic Ridge is able to amplify which gives the upper energy associated with the ULL in the center of the country a clear path to track northeast instead of due east. Additionally, the NAO is negative at this juncture so this usually keeps surface low pressure systems closer to the coast instead of well off the coast. The +PNA gives us hope the northern energy coming down from Canada will try to phase into the southern energy. If successful, you can expect a Roidzilla-esque storm to impact the area Sunday into Monday. Right now, the EURO shows a Godzilla storm and that is WITHOUT a phase. So, imagine if it begins showing a phase. 


This is what I mean. The storm the EURO shows hitting the area on Sunday is all southern stream driven. From the map above there is no clear phase between the northern and southern branches. That goes to show the potential this system has.

EURO verbatim has this at 989mb. If a phase were to happen, not only would the surface low be tucked in closer to the coast but the pressure or strength would be sub 970mb. Right now NYC Metro is absolutely hammered on the EURO. With a phase - which is entirely possible due to the -NAO/+PNA duo - areas further west would also get into the action while much of the region sees a crippling blizzard. 


Here is the EURO again Sunday morning looking at 500mb height anomalies. The block in the northern Atlantic into Greenland is key in this setup. It really does help slow the flow down and allow the upper energies to convene along the coast. Also, the separation between the ULL's is also very important and the EURO does a nice job in showing this. This is why it is the most bullish model with the Godzilla on Sunday. 




Both of these images are from the GFS model. The biggest difference between the American and European model is the lack of separation with both ULL's, and the inability of the ULL in the center of the country to dig deeper into the eastern CONUS. The GFS looks very progressive with sheared out upper energy. This is a typical bias of the GFS. Also, I feel the GFS struggles with storms involving a -NAO. I do not think it does a good job of recognizing the block which in turn effects how it handles the pattern downstream. 

CONCLUSION:

I actually feel very good about this storm coming to fruition for the area. This is the first storm all winter I have felt good about. It took me awhile to get around to Jonas, but for some reason my gut is telling me this one will happen. I really like the set-up with a -NAO/+PNA. I like how even with no phasing on the EURO it still manages to get a surface low close to the coast with enough cold air in place to support snow. I think over the next 2 days we will continue to see waffling. By the time we get to Friday I think models will begin to hone in on a Godzilla-type storm affecting the area mid day Sunday into Monday late morning. 

We will see what happens! Have a great night. 

Best,

Francesco Paparatto 
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Monday, March 7, 2016

Warmer Times Ahead

Is it safe to say the January Roidzilla was the highlight of the winter? I mean, I don't even think it is close. And the sad part is the Roidzilla, aka Jonas, did not bring the 2+ feet snowfall amounts to a widespread area. It was fairly concentrated from central and eastern NJ through NYC / LI. Central Park got below zero and we even had a severe weather outbreak. I think those may be the top 3. I think it is fair to say winter has ended. We will see record warm temperatures this week and even more mild weather on the way for the following week. 



The EURO (top) and GFS (bottom) suggest temps on Thursday afternoon will reach the mid 70's. That is about 15 to 25 degrees above normal for this time of year. May weather in March, who would have thunk it?! 



Be on the look out for rain late Thursday into early Friday. The bulk of the rain will stay to our north. Both the GFS and EURO models are in agreement of that. Do not rule out a spotty shower though. High Pressure if off to the south and east which keeps our temps fairly mild. More rain is possible Sunday into Monday next week. At this time it does not look like a high amount. 


One reason we are seeing these mild temps is because the Pacific Jet is crashing into the west coast of the U.S. This keeps the PNA negative with frequent rain storms affecting the PAC NW. Notice how the ridge builds over the east with a strong High off the east coast. 



This pattern looks to last through the week of 03/14 as well. The PNA stays negative and the eastern U.S. stays under the influence of a southeast ridge. When the Pacific Jet is strong and in control it does not bode well for cold weather lovers in the northeast. 


By later in the month - say by the 19th - the pattern tried to flip to a split-flow. This shifts the Pacific Jet south into the SW CONUS and brings the northern jet driving across the northern tier of the country. The southeast ridge moves east and a trough tries to settle into the eastern U.S. At this time I do not think it will lead to any wintry weather, but it should get cooler or at least get to average later in the month. Honestly, the weather moving forward looks very boring. Personally I appreciate the weather turning a bit milder, but storm-wise I do not see anything significant. 


El Nino should be weakening drastically as we head into April and May. By the summer we should begin talking about La Nina and how strong it may get by winter 2016-2017. We still have a long way to go before we reach that point. For now, our pattern should continue resembling one of El Nino for the most part. 

Have a good night!

Best,

Francesco Paparatto 







Sunday, February 21, 2016

02/22/16 Mo Mo: Figuring Out What's Left Of Winter

Good Morning,

So far this winter has thrown the entire kitchen sink at us. Record temperatures in December, a Roidzilla for most in January, and sub-zero temperatures earlier this month. These have been the highlights. I think most would agree this has been a divided winter. Areas N&W of NYC are well below their seasonal snowfall while those in and S&E of NYC reached or surpassed their seasonal snowfall. Only 1 more week of February is left. This means we're down to our last week of Meteorological Winter. 

Light to moderate snow may be coming down Tuesday afternoon as a weak wave tracks up the coast. Snow should change to a mix then rain by late Tuesday. A minor 1 to 2 inches of snow is possible for those N&W and N&E of NYC. Some models are showing much more in the way of accumulation but I do not think the wave is strong enough to support high precipitation amounts. Wave 2 will be stronger but since it will be tracking well west of the area that means temps will go soaring into the 50's so rain will be the main concern. Rain may continue through Thursday morning. Overall, a soggy and overcast week. 

Once the storm tracks into Canada, it will shift winds from the south to the north and help bring colder air back into the area. 



To finish out the month the GEFS and EPS are in agreement the NW flow will return and below normal temps are likely the 27th-29th. The trough axis does not support the development of any major snowstorms. The PV is over the Hudson and the flow across the country is more zonal than meridonial. We'll see as we get closer to this time frame if models begin showing any southern stream energy eject out of the STJ and possibly interact with upper energy out of the polar jet. That would support at least a moderate snowfall. At this time, models do not show that but instead think it'll be mainly cold with possibly an arctic front bringing light snow to the area. 



The March 1st-5th time frame looks more favorable for winter storm chances. The PV is east of the Hudson and the trough axis is sharper. Additionally, the NAO looks to be negative at this time. This is shown by the higher than normal heights across Greenland into Baffin Bay / Davis Strait. The PNA will remain positive thanks to the anomalous trough over the Aleutian Islands and the AO will also remain negative. The key will be to see how much staying power this pattern has. If it's transient, it will be difficult for a storm to get organized in time before it breaks down. The timing will be critical for whatever upper energy we have to work with. So, keep in mind the March 1st-5th time frame for a possible winter storm. At the very least, it should remain cold (dating back to the February 27th period). 


According to the CFS OLR forecast, the last week of February will feature impressive negatives over the Dateline which supports a trough over the Aleutian Islands and a ridge up the west coast. As we just saw, the Ensembles do a nice job of depicting just that. Notice by the time we get into March, especially after the 6th, the negative OLR anomalies begin to shift east closer to 120W than 180. With forcing shifting east, this will also push the trough over the NPAC east and break down the +PNA. If you think back to December and early January, this was basically the same situation where tropical forcing was east of the International Dateline. 




The CFS Weekly does a nice job showing the NPAC trough gradually shifting east week 1 to week 2 of March. Notice the negative anomalies beginning to show up over the western U.S. with the higher heights focused across Canada. 



The CFS is not the only piece of guidance showing this pattern change. The GEFS and EPS agree negative heights will spread into the west coast by the 6th of March. The ridge will shift into Canada and the flow across the U.S. will be mainly progressive with little amplification. We will see how deep the trough gets over the western U.S. The deeper the trough, the more amplified the southeast ridge gets over the east and the warmer our temperatures get. 

While the mean trough will try to stay confined to the Aleutian Islands, it looks like lobes of upper energy will break off it and come crashing into the west coast to prevent the PNA from going positive. Again, this is reminiscent of the pattern we saw in early January. In December, the PNA was very negative and the east was seeing temps way above normal. I do not see that type of pattern returning just yet, but even early January was a frustrating time for winter weather lovers located in the east. 

In sum, I think February 27th-March 5th will be a cold period with 1-2 winter storm chances. Once the 2nd week of March rolls around, I think the unseasonable colder air will retreat north and our temps will hover around normal to slightly above depending on how deep the negatives get in the western U.S. Normal temps for CPK NY in early March are in the lower 50's. If the aforementioned pattern comes to fruition winter will be coming to a vast ending sooner than later. 







Wednesday, February 3, 2016

Models Completely Lost - February 8th-10th Storm Threats

Temperatures neared 60 degrees today with heavy rainfall and localized flooding. The snow pack left from the Roidzilla almost two weeks ago is quickly melting away. It has been your typical El Nino winter to this point. As shown in the video I put together the pattern beginning this weekend is going to lead to a long stretch of below normal temperatures and an active period for tracking snowstorms. I want to focus my attention in this blog looking at the potential storm threats next week. If you're interested about how the upcoming pattern is coming together (tropical forcing / minor Sudden Stratospheric Warming Event) please watch the video.



Weather models are advertising 2 possible storms for early next week. During this write up I will refer to them as Wave #2 and Wave #3. Wave #1 is a minor event that may bring light snow accumulations to the Jersey Shore, NYC, and Long Island. At this time I think this is a C-2 inch ordeal that may not stick very well to roadways. Timing would be after Midnight late Thursday through 7am Friday morning. 


Here is this afternoon's run of the 12z EURO 500mb height anomaly valid 1pm Super Bowl Sunday. I labeled both waves and the northern s/w (short wave) over eastern Canada. Earlier in the week models were keying in on Wave #2. The 500mb trough was closing off further west allowing heights to rise along the EC (east coast) to track a strong surface low up or just off the coast. Recently, models disagree with that notion and are now keying in on Wave #3. Where Wave #2 tracks, how strong the storm gets, and its speed of departing the region DIRECTLY influences how Wave #3 comes together. According to the latest EURO run, the 500mb trough associated with Wave #2 closes off too far S&E which tracks the storm east of the BM (benchmark). It's fair to say Wave #3 de-amplified the trough from Wave #2 which is one reason why H5 closed off too late. 


Moving along to 7am Monday, Wave #3 is struggling to come together. You can see Wave #2 is east of the BM but the spacing between it and Wave #3 is too close to allow amplification in the 500mb trough. Further, notice the green "X" over the Great Lakes. This is where this afternoon's run of the EURO closed off H5. The 500mb upper low ends up staying stationed over the Great Lakes instead of digging into the CONUS. The purple "X" is where the 00z EURO run from last night had the 500mb upper low. It dug nicely into the CONUS then tracked east to bring a powerful Miller-B type storm to the area Tuesday of next week. 


To get an idea of why the EURO did not dig the H5 upper low nearly as much as its 00z run, let's take a look at the 500mb vorticity map valid 7pm Super Bowl Sunday.  We'll stay with the green and purple theme. Green is today's 12z EURO run and purple was the 00z EURO run from last night. In the 00z run, the EURO consolidated the upper energy better and dug it into the central U.S. On the 12z run, the EURO is a bit more scattered with the upper energy and tracks it more east than south. This is the main reason why the 12z run closes H5 off over the Great Lakes while the 00z run closed off in the east-central U.S. Meanwhile, Wave #2 is still hanging around the Southeast U.S. dampening heights. You can see it also is struggling with consolidating upper energy at the base of the trough. The trough remains open and positively tilted. 

Taking this information into consideration, here are my thought's:

1. I do not like Wave #2 very much. I think the short wave trough in eastern Canada acts as too much confluence to allow heights to rise along the EC. Sounds familiar, right? Except the Roidzilla two weeks ago did not have another storm right on its heals. Wave #2 and Wave #3 are basically de-amplifying each others flow. 

2. One of two things need to happen to get either Wave #2 or Wave #3 to pan out for the area. Either Wave #3 slows down and separates itself from Wave #2 more, or Wave #2 moves out faster than currently modeled to give Wave #3 more space to amplify into the east coast. With an anomalous western ridge I do not see how the upper energy associated with Wave #3 does not dig into the eastern CONUS. I think if Wave #2 was out of the picture this afternoon's run of the EURO would have looked like its 00z run. 

3. Unfortunately we run the risk neither wave comes to fruition. If the spacing between both waves remains this close, I fear the upper energy will not come together to promote cyclogenesis. Over the next few days it will be very interesting to see if models focus less on one wave and more on another. Maybe Wave #2 and Wave #3 come together as one wave. I think that's unlikely right now but you never know based off model performance this year. 


The upper energy associated with both waves is still located over the eastern and central Pacific Ocean. We have seen drastic changes in modeling once the sampling of these upper energies became clearer. It is important to keep in mind we're working with a ++PNA (again, watch the video) and an EPO / AO going from positive to negative. I personally think these type of signals under an El Nino regime means one of these two storms will come to fruition. It's just a matter of which one. We'll know more by the weekend! 

Thanks for reading. 

Best,

Francesco Paparatto