Upcoming!

I will be writing again soon and will have a review and if needed change to the summer forecast, as we are now in the second half of summer. Then for late August there will be a Fall forecast. Expect more pieces not just on Northeast weather forecasts, but on the weather world in general. Topics will include the tropics, severe weather, interesting weather phenomena, and the climate!

The Same Old Tune

   Hot, humid, and scattered storms. Sound Familiar? That’s because we have been beating the same drum since May. This week the beat goes on and so does the heat. Sunday was another hot one for the Mid-Atlantic, Monday the same, and Tuesday even worse. Wednesday will be a turning point though with temperatures forecast to not hit 90 (but remain very close).
  

30 day observed precipitation

In fact, after midweek the temperatures should begin to fall into the mid to upper 70s. This comes with the potential for rain. At the moment there does not appear to be much of a flood threat with this rain, unlike with our past storms. Although, we have experienced above normal rainfall for the past 30 days, which means that any heavy rain has the potential to produce flooding.
   For those living north of the mid-Atlantic region, it has been warm but not uncomfortably so. This should continue, as should the above normal rainfall. Most of our heat has been coming from a high pressure system located in the southeast near the Gulf. This has sent heat north and at times up the I-95 corridor. Northern tracking systems have suppressed the heat, keeping it down around Pennsylvania and south.
   Unfortunately for those experiencing the heat and humidity now, there is a high chance that it will continue this way through early July, as the pattern does not want to shift. We will have breaks such as this weekend in the heat, but the same old tune is playing and nothing seems to want to turn it off. For now it will continue as it does.

Weekly Run Down

Monday- Mid Atlantic and I-95 are hot. Very little rain.

Tuesday- Similar to Monday for the same areas, but hotter. Mid 90s around Washington and Philadelphia. Mid to upper 80s for New York to Boston. Storm threat as front moves in.

Wednesday- Beginning to cool off. 80s throughout the region. Clear skies for many.

Thursday- Cooler. 70s north 80s south.

Friday- 70s south 60s north. Storm threat is back.

Saturday- 60s throughout the region. Rain+storms carry through weekend.

Bill the Inland Cyclone

   It is a day after landfall, and Bill has since moved up to the Dallas/ft. Worth area. Amazingly though, Bill is still a tropical depression with fantastic structure for a storm that has been over land for the past 24 hours. In fact, Bill looks to have better structure and convection that it did when it came on shore yesterday morning. 
Yesterday morning Bill made landfall packing 60 mph winds and a minimum central pressure of 997mb. Currently it’s a tropical depression with winds of 35 mph and a minimum central pressure of 1002mb.

24hr past precipitation

   The winds are not the main threat from this inland cyclone, but the immense amounts of rain are. Up to 11 inches of rain have fallen across Texas since the storm made landfall. Unfortunately there is more to come. For Texas and Oklahoma 3-7+ inches of rain are forecast over the next 5 days.

5-day precipitation forecast

   Interestingly enough this phenomenon of inland cyclones was studied in 2013 by Theresa Andersen and J. Marshall Shepherd of the University of Georgia in Athens with NASA funding. The ability for an inland cyclone to maintain its strength has been dubbed the “Brown Ocean” effect where "The land essentially mimics the moisture-rich environment of the ocean, where the storm originated”

   The researchers combed through NOAA archives, analyzing every land falling tropical cyclone from 1979 to 2008.  Storms had to meet the criteria of retaining a measurable central pressure by the time they tracked at least 220 miles (350 kilometers) inland, away from the maritime influence of the nearest coast to be part of the study.
Their research found that of the 227 storms they looked at, 45 maintained or increased strength while over land. They found that of the 45 storms that had deviated from the norm, they did so through three different processes. NOAA categorizes storms that lose tropical characteristics as “Extratropical” systems. This term is broad in the sense that it does not define the different types of extratropical systems that can exist. Of the 45, 17 of the inland storms fell into the cold-core extratropical cyclone category where the storms derive energy from clashes between different air masses. Another 16 of the inland storms were part of a group classified by the study as TCMIs (tropical cyclone maintenance and intensification events). These storms retain their tropical characteristics and warm core over land, allowing the storms to deliver higher amounts of precipitation.  The rest of the storms exhibited hybrid characteristics, combining features of a cold core system and a TCMI to varying degrees.

Image Credit: 

NASA/Kathryn Hansen

   For these storms to exist and at times thrive, three observable conditions needed to be present. “First, the lower level of the atmosphere mimics a tropical atmosphere with minimal variation in temperature. Second, soils in the vicinity of the storms need to contain ample moisture. Finally, evaporation of the soil moisture releases latent heat, which the team found must measure at least 70 watts averaged per square meter. For comparison, the latent heat flux from the ocean averages about 200 watts per square meter.”
In regards to Bill, it appears this storm may be a TCMI, as it is still a warm core system with immense amounts of precipitation. It will likely shift to a cold core system as it swirls north into less tropical air, but the precipitation amounts will still be large.

   The Northeast will be this storms last stop, as it draws its moisture all the way of to Massachusetts. It will likely have lost all of its tropical characteristics by the time it arrives, but it will still have plenty of rain with it. From West Virginia all the way up into Maine, a swath of 2-5 inches of rain can be expected. This rain will arrive for the weekend, so be prepared, pack an umbrella, and be wary of flash flooding.



Information was gathered from the article "Brown Ocean' Can Fuel Inland Tropical Cyclones" By Kathryn Hansen 

Summer 2015 Forecast

    As meteorological summer begins, it is worth looking at what to expect. Of course the big name being thrown around has been El Nino, and that could certainly have an effect on our weather patterns. Although it’s the biggest name, the El Nino is not the only player around that will influence the coming months. I am going to take a look at the possible influences on the summer and break them down.

             

                The El Nino

                SOI (?)

                MJO      

                PDO

    Let’s start with the developing El Nino. Forecasters have been calling for a strong El Nino to form this summer, but so far that has not been the case. Past ENSO (El Nino Southern Oscillation) values, beginning in September 2014, maxed out at +0.7 in October and November, but has since stagnated, if not decreased in strength since then. Values December through March have hung around +0.5-+0.6. For a more definitive El Nino to form these values will have to show a distinct rise, and to fulfill the possibly overblown El Nino forecasts, it would need to reach above +1.0-+1.5. The strong El Nino forecasts have happened before, most recently this past summer and early fall, where forecasters called for a very strong El Nino going into winter, but that never materialized. ENSO values are given over a month after they happen, so the values for April and May are not out yet. If they yield a strong rise in ENSO values, then the strong El Nino forecast may be right, but observations so far are not supporting the idea of high ENSO values.

    This is important to consider because the strength of the El Nino will influence our summer weather, which includes; the tropics, temperature, and precipitation. If the El Nino is as weak as is currently believed, then other factors will have more influence on our summer weather. If the El Nino forms we may be in for a seasonable to cooler than average summer. Precipitation for the Northeast will not be effected significantly by the El Nino this summer. For many the most important portion of an El Nino summer could be a less active Hurricane Season and some drought relief for California.

    If the El Nino weakens any more or does not strengthen the effects will be more negligible, and the summer could be more variable, and other factors, which I will introduce, will be more influential.

    Recent forecasts made by WSI and The Weather Channel are more focused on the SOI values being shown, which are measurements of pressure differences between Tahiti and Darwin, Australia. These fluctuations are a product of ENSO shifts, and thus a forecast referencing these values are more or less references the state of the ENSO. I have spoken about the effects of El Nino on the summer and most likely do not need to go into further detail. I will however provide with the forecast from WSI and The Weather Channel for reference.

    Now for the MJO (Madden–Julian oscillation), this is a gauge of activity across the tropics. As of this moment the MJO has moved into the western hemisphere. This means that tropical energy has shifted into the tropical Atlantic and will be an influence on weather. The MJO moves west to east, and is important for mid to long range forecasts. It will not help us understand what August will be like, but can get us through June and early July. While the increased MJO is around, which it has been for almost two weeks, intense precipitation events are more likely, as there will be more tropical moisture and energy to tap. This has been witnessed in the south and northeast recently, where mist air that originated from the tropics, came up and prepared the stage for hefty amounts of rainfall. As long as the MJO is around, storms packing tropical moisture will be quiet potent.

   Finally, the Pacific Decadal Oscillation, PDO. At the moment the PDO is at .99, and presumably dropping. A lower PDO, although not negative, will hamper the growth of a strong El Nino event, and lead to summer heating across the eastern two thirds of the United States. The PDO has been dropping at an average rate of .18 per month since December, which, it being June, would put us at roughly .81 or lower, assuming it’s a steady drop. This will set up a pattern where the El Nino will struggle to strengthen, and the MJO + PDO will go to work to warm up the country east of the Rockies. Warm and moist air will dominate for a time being, with interspersed moments of cool air as usual.

    In regards to Hurricane season, having the MJO around and warm air, may give life to the tropics, contradicting current forecasts. It is a possibility. I am not making a hurricane season forecast of my own.

Here’s the Run Down

June-

         With the MJO around and a weak El Nino, the Northeast will be warmer than average, with a
heat wave toward the end of the month. Precipitation for the past few months has been below average, but I believe June will erase these deficits.

July-

         The early part of July should be warmer than average, and with continued higher precipitation. From mid-July to the end of July, temperatures should begin to average out.

August-

                  Average temperature, but without the MJO, lower amounts of precipitation. 

*Disclaimer: This is my first ever season forecast. Do with that information what you want*