Pattern Amplification Likely, A Tale Of Two Octobers

Good afternoon, 

I want to give a quick update on what the weather pattern looks like as we head into the 2nd half of October. There are some interesting features that deserve some attention. 

The mega-typhoon that is re-curving near Japan is going to spark pattern amplification downstream into North America. The global upper air wind pattern is going to change so that colder air makes its way into the U.S. while warmer air overtakes Canada. I'll show you what I mean... 

Here is a look at our current 500mb pattern from the 12z GFS model. Fairly zonal in the eastern U.S. with a cut-off trough in the western U.S. At this point, a ridge is just now beginning to develop in the Northern Pacific and the EPO (eastern pacific oscillation) is transitioning to a negative phase. 

When we fast forward to the weekend, a full fledged ridge is now dominating in the Northern Pacific and a 

-NAO/-EPO pattern ensues. The -EPO basically means the upper level winds in the Northern Pacific have transitioned from a progressive stage to one that is cut-off by a large ridge, allowing colder air bottled up in Canada to downstream into the U.S. 

And even going beyond the weekend into next week, the GFS still has a PV (Polar Vortex) over the Hudson Bay with a nice trough in the eastern U.S. At this point though, the -NAO is gone but the -EPO signal is still there. 

Just in case you were wondering, the EURO model also has the same set-up as the GFS in regards to the upper level pattern. Strong ridging in the N. Pac. and potent lower heights in the eastern U.S. 

You can see negative temp. anomalies are going to overtake nearly two-thirds of the country by the weekend and into next week. This definitely calls for cooler than normal temperatures to filter into the central and eastern U.S., possibly as high as -8 to -12 degrees below normal, which is fairly significant. Of course if you are a cool-weather enthusiast, this is all music to your ears. 

In terms of precipitation, the amplified pattern is going to bring wetter conditions into the heart of the country and New England as well. 

The PNA, or western ridge, has been non-existent since fall has begun. There has been constant lower heights, or trough's, in the western U.S. This is evident by the large blizzard that brought parts of the Rockies states 40+ inches of snowfall. 

One of the downfalls with not having a western ridge is all the energy that comes with the -EPO consolidates in the western U.S. or middle part of the country. What this usually leads to is storms that cut to the west of the NYC Metro area. If the PNA were in a positive phase, this means the entire west coast of the U.S. is under positive height anomalies and the energy is forced to consolidate somewhere along the east-central or eastern U.S, because that is the way the jet stream would flow. 

Here is a general map I made with my thoughts on this months second half. With the pattern coming to life, there will be more storms to keep an eye on that should bring mainly rainy conditions to the Northeast. However, the upper tier of the country and interior PA/NY could see their first flakes of the season depending on how much cold air is available from the -EPO/-NAO pattern. If the -NAO subsides, much of these storms will likely cut to our west. 

We'll see what happens! Have a good day. 

Francesco Paparatto

Notes:

1. 2013-2014 Winter Outlook to be released Thanksgiving Day

2. Join the forum! www.njstrongweatherforum.com

3. Happy Columbus Day! 

Invest 97-L Potential Impact

Location: 20.4°N 86.0°W

Maximum Winds: 35 kt Gusts: N/A

Minimum Central Pressure: 1006 mb

Invest 97-L will momentarily be entering the Gulf of Mexico. The GFS model is showing this storm strengthening to a tropical storm, perhaps even a weak category 1 hurricane. If this occurs, this storm would be named Karen. Once Karen forms, according to the GFS, it gets captured with a trough diving into the southeast and tracks up the east coast- bringing several inches of rainfall to NYC Metro, eastern PA, and NJ regions.

00z GFS:

Hour 120

Hour 126

However, I think there are some factors that need to be taken into consideration when looking at this system and the environment it is trying to develop in. 

Firstly, upper level winds are favorable now but they will not be once this system reaches the northern Gulf. This is due to the fact that there are two High Pressure systems located over northeastern Mexico and northern Florida. The wind patterns associated with both these upper level phenomena's are overlapping each other and is causing a lot of friction along the Gulf coast. 

Next is the TCHP (Tropical Cyclone Heat Potential). To put it simply, this graphic shows how deep down the warm water of the ocean extend. Sure the ocean temps may look nice and warm at the surface, but tropical cyclones need those warm temperatures to extend deeper into the ocean's layer. Since 97-L is projected to track into the east-central Gulf, the TCHP is very low there. 

SST's are ok (actually a little cooler in northeast Gulf), but like I said above, TCHP is a far greater factor when trying to forecast the intensity of a tropical system. 

My thought's? 

I think the GFS is over-doing it a bit. However, I also think the EURO is too far east with the system. I do think we will see at least moderate rainfall early next week, but it will just be due to remnants or as part of the moisture that comes with the cold front. Initial thoughts are a 1-2 inch rainfall, with pockets of 2-3 inches of rain wherever the heaviest of the remnants track toward (inland along eastern PA, or up along the immediate coast)? I would not be surprised to see this system fall apart altogether. 

Rain at this point would be welcoming anyways. Most areas have not seen measurable rainfall since September 20th! Tuesday into Wednesday of next week would be the time frame to watch for this potential storm to impact the area. 

Have a great day!

-Francesco Paparatto

Notes:

1. Did not mention this, but do not be surprised to see pop-up showers over the weekend (Saturday and Sunday). Atmosphere is a little unstable and we are under a tropical flow. 

2. 1st half of October will start way above normal, but it looks like it wants to finish on the cool side. More on that over the weekend

3. Join. The. Forum! www.njstrongweatherforum.com 

4. 2013-2014 Winter Outlook will be released on Thanksgiving Day

Pacific Pattern Taking On A Familiar Form

Before I get into the meat and bones of the blog, I have to mention that the verification scores on the global models as of late have been dreadful. The EURO is still scoring best, but not as high as it usually does. I'm not sure exactly why this is the case but the SSW (Sudden Stratospheric Warming) that recently took place over the last month to five weeks or so could be a reason.

For those who remember upper level patterns well, you can recall that this past winter seemed to always feature a large trough over Alaska with a constant upper-level low stalling & spinning in the PAC. NW that would disrupt the flow for the rest of the U.S. It was not until the SSW around mid-January that the 500 mb pattern "relaxed" a bit through most of February and that was when we saw most of our colder than normal and snowier than normal weather conditions along the northeastern U.S.

I can not help but notice that the current 500 mb pattern is heading in a direction similar to what the 2012-2013 winter featured...

Here is 12z EURO at 72 hours:

                              

Trough over Alaska and PAC NW with a temporary one in the eastern U.S. behind a cold front (I will get to the developing -NAO as well later on).

12z EURO @ 120 hours:



Much of the same (besides the -NAO).

12z EURO @ 216 hours:



Again...much of the same.

Here is a zoomed in look at the U.S. from 12z EURO @ 168 hours:



It will be interesting to see how the ENSO and PDO look 4-6 weeks from now. If this pattern persists, it would become apparent we are on our way to another negative PDO winter (not all that surprising since these things come in cycles). The ENSO has been interesting in the fact that it has looked pretty "Nino-ish" to me for much of the summer, which is why I think the hurricane season has been relatively quiet. It still remains in question, at least for me, whether or not this warming trend continues. It is difficult forecasting the ENSO far in advance which is why it is best to focus more on factual data.

Meanwhile, the NAO will be taking an impressive tumble downward, but the lack of Polar Vortex' given the time of year, plus the -PNA (zonal flow) in the west, should keep our temps around average still as we finish off the month of September.

Projected NAO from the GFS...




Have a good day,

Francesco Paparatto



Notes:

--2013-2014 Winter Outlook to be released Thanksgiving Day--

--All images of this blog courtesy of WeatherBell Analytics--

--Come register at the NJ Strong Weather Forum--

http://www.njstrongweatherforum.com/

El Nino-Like Conditions Hindering Hurricane Development, Atlantic Not Helping

We are half way through the 2013 Atlantic Hurricane season and there has still not been a hurricane.

What gives!?

One thing I do find interesting is subsurface temps. in the Pacific since mid to late May have been rising. 

The ONI value for June, July, and August is not in yet, but I'm fairly certain it will show a positive (warming) trend in the 3.4-Nino region since real-time data continues to show gradual warmth over that area in the last month. For May, June, and July...the ONI was at -0.2 which is indicative of ENSO-neutral. In fact, "La Nada" has been in effect dating back to March of 2012. Therefore, the ENSO has not had any affect on our weather pattern for the last year and a half! 

Check out the two 500mb anomaly images of the Pacific Ocean from the 12z GFS below. The first one is valid for September 6th and the second one is valid for September 11th. 

                           

Both of these images show positive height anomalies continuing in the Pacific for at least the 1st half of September. There is even constant ridging being shown in the Pacific Northwest of the U.S. (upper right corner of those maps). What this is telling me is the Pacific is undergoing a transition of breaking out of the year and a half long La Nada and trying to emerge into an El Nino state. I can not say with guarantee we are heading toward an El Nino until official reports and observations from the Nino regions prove otherwise. But latest indices are enticing, to say the least. One thing for sure is La Nada will persist through the upcoming fall season. 

How about the Atlantic Ocean? 

The NAO has been positive for much of the summer. Ridging has been concentrated in the central Atlantic, while the northeastern Atlantic (near Greenland) has been under the influence of trough's. Between the ridging in the Pac. NW and the central Atlantic, the eastern CONUS has enjoyed an average Meteorological Summer with episodes of troughs getting into the region. 

This has allowed the SAL (Saharan Air Layer) to remain intact over the Atlantic for much of the season. This GIF taken from WeatherBell will show you what I mean...

The colors represent the dust coming out of western Africa. A new wave of SAL is set to come off of Africa by the weekend. 

Between the combination of westerly winds in the eastern U.S. caused by the constant ridging in the west, the SAL in the Atlantic, and the lack of blocking in Greenland...the hurricane season has not gone as expected thus far in 2013 (even with an MJO favored for tropical development). Additionally, the recent trend of warming in the Pacific has caused the upper level wind flow in the Atlantic to remain unfavorable. 

Speaking of MJO, the EURO wants to take it into the COD (circle of death) by next week:

The only silver lining I see for those who are looking for tropical development is some long range models are trying to push a ridge into the eastern U.S. which would force the ridging over the central Atlantic to propagate east-northeastward. Whether this comes to fruition or not remains to be seen. Also, it only takes one storm to really make a hurricane season one to remember. There is still the 2nd half of September (I'm forecasting 1st half of September to remain quiet) and all of October. We'll see what happens. 

Take care,

-Frank 

Notes:

1. Register to the NJ Strong Wx Forum. Now up to 183 registered members with lots of great minds to share valuable information

http://www.njstrongweatherforum.com/

2. 2013-2014 Winter Outlook to be released Thanksgiving Day. 

A Trip Down Memory Lane: December 26-27, 2010

Got that summertime sadness?

There is not much, weather wise, to talk about for at least the next two weeks. So lets take a look back at one of the most memorable blizzards to strike the NYC Metro area.

December 27, 2010.

Here was the final snow map for the Boxing Day Blizzard:



This impressive storm dropped 10+ inches of snowfall from North Carolina all the way up into Maine. As you get into NJ, there are widespread 1-2 feet snow amounts and, locally, 30+ inches of snow in northeast NJ and parts of southern NY state.

Here is a close up of the northeast:



What was the most essential factor that put this storm together? The -NAO.



An NAO in a negative state brings positive heights into Greenland which allows the jet stream to dip and create a trough along the eastern U.S. This creates an arctic flow of air to filter into the eastern U.S. Now, compare the graphic above created by TWC with the 500mb map the day of 12/27/10...



You see that huge trough in the eastern U.S. with low heights extending all the way down into Florida? That is a very amplified pattern of a +PNA, -NAO, and -AO. This looks very much like the TWC graphic. The -NAO allows two bundles of energy to come together which ultimately develops a powerful Nor'easter, in this case known as the "Boxing Day Blizzard" or in my own terminology, a "Godzilla."

Here are a series of my favorite images or gifs of this historical snowstorm:


























And here are some gifs...

http://cimss.ssec.wisc.edu/goes/blog/wp-content/uploads/2010/12/101226-27_g13_wv_anim.gif

http://www.erh.noaa.gov/okx/SOO/case_studies/12262010/sfcir.gif

http://synoptic.envsci.rutgers.edu/riggi/101226_27_kdix.gif

http://www.erh.noaa.gov/okx/SOO/case_studies/12262010/500mb.gif

Have a nice night,

-Frank

Exactly How "Cool" Will It Get?

By now, we should all be aware of the pattern change that has taken place last week which has ridden the insanely hot temperatures and unbearable humidity. I blogged about it HERE on July 15th...

The biggest reason for this pattern change is due to the abnormally strong PV, or Polar Vortex, this time of year.

The positive heights in the north-central Atlantic, northern Canada, and Greenland...have created an unusual blocking pattern for the commencement of August. Temperature departures relative to average will be between -1 and -4 over the next 10 days or so in the northeastern U.S. and mainly the northern half of the Mid-Atlantic. 

A zoomed in view into the eastern U.S. shows the negative temp. departures from normal nicely. 

In terms of high temperatures, we will be talking mainly 70's (it actually never got out of the 60's today around the Tri-State area due to clouds and rain). Low temps will get into the 50's. Northwestern sections of the of I-95 could see cooler readings, but for the most part, 70's which is still impressive for what are supposed to be the "dog days of summer." 

One thing to also keep in mind is with the battle of positive and negative height anomalies fighting around the mid-section of the country and eventually into the northeast, it could spark the threat for storms to develop. Think of it as a "friction" between the two. It could be enhanced along a front which would develop ahead of the PV that will be situated in southern Canada as it moves on east. 

All in all, 1st half of August should be expected to be cooler than normal with periods of rain at times. The tropics should continue to remain quiet until the 15th. Afterwards, it is beginning to look like fair game for this season to really start picking up as dry air begins to dissipate in the Atlantic. Stay tuned! 

Enjoy your weekend, 

-Frank Paparatto 

Quick Check On The ENSO & Upcoming Winter

ENSO, for those who do not remember, stands for "El Nino/Southern Oscillation." Depending on which phase it is in (hot or cold), will let us know whether we are trending toward an El Nino or La Nina winter. It could also be La Nada, which means neutral. ENSO is one of the most significant factors in formulating seasonal outlooks, especially winter.

The dynamical and statistical models show predominately "La Nina-like" conditions currently in the central Pacific. Further examining of the actual values and taking a mean of those values, however, show mainly La Nada conditions. 

The plumes as of July 1st from the EURO model are trying to show a positive correlation trend begin by August and continue through the fall months. One thing to keep in mind is these plumes change month-by-month and sometimes begin to show different trends, so do not take them verbatim. 

As of now, it is too difficult to tell what the upcoming winter season will feature in terms of ENSO. If I were to look at historical trends dating back to 1950, I would say the upcoming winter season has a good chance of staying around neutral, with some "Nino-like" characteristics. But that will also depend on the PDO and whether or not it can climb out of its negative phase it has been in for quite some time now. 

My 2013-2014 winter outlook can be expected to be released December 1st. Last year, I was with EPAWA when I did the 2012-2013 winter outlook and I had the help of some great Meteorologists, such as Bobby Martrich and Jim Rinaldi, both based out of PA. 

That's all for now. Arrivederci. 

-Frank Paparatto