Hi everyone. I am officially going into storm mode on the site. This means I will be updating at least daily on the status of this very large storm coming next Tuesday. This past week I have been tracking a tropical system (now TS Sandy) that has the potential to ride up the Eastern Seaboard and retrograde west into the mid-atlantic, causing widespread damage. Even though we are a week out, there has been an unusual consensus with the forecast models up to this point, which is concerning. Like always, there are two possible scenarios.

Scenario 1: Hurricane Sandy retrogrades west into mid-atlantic

Most of the models (European, nogaps, canadian, japanese, and UK) have been showing Sandy strengthening into a  hurricane, phasing with the approaching cold front, and retrograding westward into the trough. This retrograde would have devestating effects on the Northeast region. The models are also projecting Sandy having a minimum central pressure of 940 mb, equivalent to a category 3 storm.

When Sandy starts to curve back west, she will also bring in cold air from the northwest. Because of her projected strength, this would cause much of the rain to turn to snow in some areas. Accumulations could measure in feet in some places as the cold air is rushed in aloft. The storm, of course would also bring heavy rain and near hurricane force winds (much like Irene last year). Rain measurements from a few of the models have measured near 10 inches in places. Obviously, this is just a scenario that the forecast models have been projecting. It may or may not come true. But because it is possible, we have to make the necessary precautions.

Here is the snowfall map (in inches) for the storm:

Scenario 2: Out to Sea

As of right now, only one forecast model is showing the out to sea scenario: the GFS. The GFS model is known to be the second most reliable after the European (scenario 1 model), For this scenario, Sandy would strengthen into a sizable hurricane, but she would  never phase with the front or trough. As a result, she would turn out to sea, giving us minimum effects. See the map below for scenario 2:

Here is a larger scale map showing both scenarios:

Either way the storm goes, anyone up and down the eastern seaboard needs to start thinking about preparations for this storm. It’s better to be prepared, even if the storm heads out to sea. Preparations include: making sure you have batteries, food, flashlights etc. As we head closer to next Tuesday, tying down/bringing in any outdoor furniture would be a good idea as well.

Yes, we continue to progress to winter. The National Weather Service has posted a Freeze Watch for tomorrow night. The watch includes all counties north and west of Philadelphia. High temperatures on Friday will reach the mid-60s. A clear night sky will induce radiational cooling, dropping low temperatures at or below 32 degrees early Saturday morning.

Here is the NAM model. This shows 2m temperatures (6 feet above surface) of the Northeast at 5 AM Saturday. The freezing line stretches down to Philadelphia:

Most computer models are in consensus for this “first freeze.” The NAM and GFS forecast model both show the freezing line creeping all the way to South Jersey early Saturday morning. It shouldn’t stay below freezing for that long as temperatures will escalate near 60 on Saturday. This colder stretch is all in part to a strong high pressure sitting just to our west. Cold air from Quebec is being wrapped around the high and is coming down to the I-95 corridor.

Here is the GFS showing the high pressure just to our west at 2 AM Saturday. I drew arrows representing the cold and warm air to help people visualize the model:

Next week, a warm front followed by a weak cold front will pass through on Monday. After a cooler Tuesday, temperatures should slowly increase into the end of next week before a strong cold front arrives next weekend. The week of 22nd will likely have highs consistently in the 50s and lows near freezing.

Remember: First freeze is coming tomorrow night… put away any small plants for the night, to be safe.

Yes! Philaburbia is back. Winter, snow, ice, and sleet are coming. It should be a wild and entertaining ride.

First on our agenda today are some stats from this summer. It was the 3rd warmest summer on record in the contiguous United States with an average temperature of 74.4 degrees. In the northeast, we had the 10th warmest June-August on record. Considering September was fairly average, I do not expect this rank to change significantly. Precipitation-wise from June-August the northeast received close to the average amount of rain expected. It was the 18 driest June-August overall in the country.

All this data can be found here… take a look, there are some very cool maps: http://www.ncdc.noaa.gov/sotc/national/2012/8

Tropics! In May, I predicted 10 named storms this year with 2 landfalls. In actuality, there were 14 named storms, 8 hurricanes, 1 major hurricane, and 3 US landfalls (Beryl, Debbie, and Isaac). My forecast was based on the weak el Niño forming from a fairly weak La Niña in the winter. Since there were only 7-8 years of this pattern in record, I did not have much data to work with. Even though Isaac created massive amounts of damage in the South, no major hurricane hit the Gulf or East coast this year. Hopefully this pattern will continue for as long as possible.

Here is the El Niño/La Niña map. Just as a refresher, positive anomalies mean El Niño; negative La Niña:

Now for some current weather:

A weak low pressure will pass to our south and head out to sea. Some of this moisture from this front will reach our area tomorrow and Wednesday before high pressure sets up in the Southeast. Temperatures should increase by the end of the week (maybe some 80s), before a strong cold front crosses this Saturday Night/Sunday. After the front crosses, expect temperatures to tumble. It will likely be in the 60s next week and could drop into the 50s for highs the week after. It does not look like summer is returning for quite a while.

Here is the GFS model at 8 AM Sunday showing the cold front crossing the region. I made some cheap graphics to help people visualize (the dark blue line means the upper atmosphere is just below freezing (supports snow), but does not, however, necessarily mean surface temperatures are below freezing):

As Joe Bastardi says: “Enjoy the weather, cause it’s the only weather you got!”

As I mentioned in my last post, Tropical Storm Isaac is bearing down on the US coastline. As of 11 PM EDT, Isaac is 65 miles south-southwest of Port Au Prince, Haiti, and is moving to the NW at 14 mph. Maximum sustained winds near the center of circulation are 70 mph, very close to category 1 hurricane strength. Minimum central pressure is 990 mb.

The forecast models have been shifting east and west every run. Before Isaac crossed the Lesser Antilles, it seemed like an East Coast threat was possible. However, Isaac took more of a westerly path and is staying more south. Most models are in agreement about Isaac’s future path. They project Isaac strengthening into a Cat 2 storm and hitting somewhere between New Orleans and Tallahassee. The GFS model shows Isaac hitting Mobile, Alabama before getting absorbed by a frontal boundary moving east. The European model shows a similar solution but instead brings some of the remnants toward our area. The Canadian model is the outlier; it shows Isaac going east of Florida and into Georgia.

My forecast:

Over the past few hours, Isaac has taken a jog to the north. This can prove very crucial in future forecasts of Isaac’s track and strength. Because of this northward movement, I will still consider a track east of Florida possible. My official forecast however, brings Isaac north of Cuba into the Gulf of Mexico and hitting near Tallahassee, Florida. If our area is affected by Isaac late next week, there will likely be some drenching rain and some light winds. Other than that, it is looking to be a very interesting week for anyone living in Florida, Alabama, Mississippi, Louisiana, and Georgia.

IF the status of Isaac changes, I will post an update on the blog.

Hi everyone. As expected, the tropics are finally starting to become more active as we head into late August. I have been tracking a tropical wave located east of the Lesser Antilles for the past week or so. Just this morning, the National Hurricane Center upgraded the wave to a tropical depression (9). I imagine by tomorrow night, Tropical Storm Isaac will be born and will strengthen into a hurricane later this week.

The major debate associated with this storm is whether it will continue its westerly track and stay south of Hispaniola, Puerto Rico, and Cuba, or take a northward turn, becoming an Irene 2.0. Anybody living from Florida to New England should be watching this storm very closely. Isaac has many similarities to Irene position-wise and strength-wise. The high pressure setup is also favorable for a EC landfall as well.

The Forecast Model Disco:

Many of the forecast models are showing Isaac moving south of Puerto Rico and Hispaniola, then taking a north turn toward Florida. Where Isaac makes the turn is becoming quite a debate between forecasters. Many of the models are disagreeing exactly where Isaac turns northward. The NAM is showing the turn over Hispaniola, while the GFS is showing the turn over Cuba.

The Importance of the Short-Range:

Even though it seems that most models are in agreement in the short-range, Irene proved to us that hurricanes seem to defy the forecast models especially during their strengthening phase.  Last August, Irene looked like she was going to stay south and head into Florida before turning NE out to sea. As Irene moved closer and closer to Puerto Rico and the Lesser Antilles however, a more northerly track looked likely; one that would affect the Eastern Seaboard.

That’s the scare with TD9/Isaac. I am not confident in the track Isaac will take until he reaches the Lesser Antilles and Puerto Rico. Until then, I urge people to continue to stay with Philaburbia as I will be doing some video updates with model analysis over the next few days.

For the second time this year, we are under a moderate risk for severe weather. A warm front moved through the area earlier this morning, which will push temperatures into the upper 90s later today. A frontal boundary is set up to our west and will push eastward into tonight. Large clusters of supercells will accompany bowing lines of storms later this evening along the front. CAPE values will also increase throughout the day, causing the atmosphere to become increasingly unstable. The heat, combined with an unstable atmosphere, is a classic recipe for a severe weather outbreak.

The biggest threat with these storms will be wind damage. But an isolated tornado or hail report would not surprise me. As daytime heating occurs, storms should start to pop up in Western PA; when these storms do start to flare, I’d expect a Severe Thunderstorm Watch to be issued.

Remember, if you can hear thunder, then go inside as soon as you can. These storms today will pack quite a punch where they hit. 

Hi everyone. This is a special alert post, as we have a threat for a damaging squall line to form. A warm front will pass through the area this morning and combine with a southerly flow, creating instability in the atmosphere this afternoon. Storms should form in northern PA by mid afternoon and start moving southeast. I do expect a severe thunderstorm watch to be issued by this afternoon, as the squall line gets its act together. The storms will mainly have very damaging winds and dangerous cloud to ground lightning. Skies should start to clear after 9 PM tonight, after the line moves through.

The Phillies are also playing tonight, and the game will likely be affected by these storms. We have another chance of t-storms tomorrow, as a cold front will move through the region.

Hi everyone. After Sunday’s storms, it has gotten extremely hot throughout the Philadelphia region. Today’s highs reached into the upper 90s with heat indices in the 100s. All of this oppressive heat will end after a cold front passes through the region tomorrow.

All of the heat ahead of the front,  instability of the atmosphere, and high CAPE values will fuel some very nasty thunderstorms tomorrow afternoon. The first cells should start popping up to the northwest of us around noon and begin to barrel southeastward toward the area. I expect a Severe Thunderstorm Watch to be issued in the morning tomorrow. The storms will have damaging winds, large hail (strongest storms will have hail that approaches 2″), and frequent lightning. If you see dark clouds tomorrow, go inside as soon as you can.

After the storms pass by tomorrow, temperatures will moderate. Highs could only reach the upper 70s on Friday, before a slight warm up for the weekend.

Hi everyone. Even though been a while since my last post, I will continue to update the blog as we head into the dog days of summer and beyond.

Our area is currently under an Excessive Heat Warning, which is in effect from Wednesday afternoon through Friday night. This heat wave will be fueled by a strong Bermuda high sitting off the Atlantic coast. Temperatures will be in the high 90s and could reach 100 or hotter in some urban areas. The heat indices for Wednesday to Friday will climb near 105 degrees A cold front will sweep through the area on Friday night. Temperatures should moderate into next week before another we heat up again by July 1st.

The tropics have been quiet. There have been a few disturbances over the past few weeks that had a small chance to turn into tropical cyclones. None, however, have really turned into anything of note.

The El Niño is starting to take over and it is looking like it will continue to dominate into next Spring and Summer: