Wednesday, February 2, 2005

Wednesday evening update

For those of you who frequent this site looking for indications of snow and storms, I hear your concerns, disappointment and gnashing of teeth. You want snow now and so do I. I know you want to see evidence that winter is indeed not over, I will continue to provide you with that evidence as succinctly as I can given the complexities of the weather. The prelude I refer to is was the early winter warmup, Blizzard #1 of 2005, and the current Ocean NAO storm. The kiss will be the Big Kahunas, which are explained towards the end of the post.


If you are new to this site, I post a “storm grade accumulation” final forecast when we are about 24 hours away from the event. This is a single snowfall number on which the forecast will be graded, as a percentage of how close the actual snow amount was to the prediction. This is done to have a reliable, accountability system by which the accuracy of my storm forecasts can be determined.

FOR YOUR METRO AREA… scroll down to find the city or region nearest you. Click on the underlined location name for a link to the NWS forecast. Or use the zipcode forecast finder at the top of the page.

Boston: I see that most forecasters are falling back in line with the snow and sleet idea from Boston to Providence. The overall 2-4” range which I hung out there on a twig early this week will stay, and I am calling for a storm grade accumulation of 2” for Logan International Airport. I know that is a pithy amount of snow for you, and granted not really a storm by New England standards, but I have to grade the forecast since it has been on the playing field for almost a week now. The period Saturday-Monday will feature seasonal temperatures and tranquil weather. Robins may be seen in force throughout the area with signs fluttering behind them which read… “Here Ye, Here Ye, Winter Has Ended.”

Metro New York: You escape this one, though northeast winds will keep it cooler than forecasts are indicating for Friday. Saturday should be a delightful day for spring-a-lings, who will dance in the streets of Times Square chanting praises that winter is finally over and the Groundhog was wrong.

Metro Philadelphia-New Jersey: Warm air inflow from the Ocean storm will cause light precip to break out Thursday night, and marginal low level cold air means it should begin as light snow or sleet. This will not last long, and is not likely to get farther west than the city. However, with time the trend has been farther west and southwest with this system. With available moisture from the southern system and the Ocean system, it is not inconceivable we see the light rain/snow mix even get to the western suburbs late Thursday night. Don’t overlook strong onshore winds of perhaps 30 mph or greater along the Jersey beaches, which will lead to coastal erosion and some inland tidal flooding. The storm eventually exits Friday, and skies are clear by the evening. Saturday will be a pleasant and warm day compared to recent weeks. Since the groundhog just predicted a return to winter soon, head out to Valley Forge for a nice walk on Saturday in the sunshine while it lasts. Plant some perennials and start weeding the garden if you get a chance.

Baltimore: If upper level moisture from the Ocean system gets near the Bay, and computer models continue to trend more northerly with the Gulf system, then this will be a minor light snow/sleet event early Friday morning. As of 3:00 PM Wednesday, the forecast is “Cloudy” but that is probably going to change. Accumulations will be less than one inch if at all in the immediate Baltimore area. In Southern Baltimore County, Anne Arundel, Howard and on south towards DC, it will be an interesting call Friday morning for school districts. If that moisture creeps north, we could have a light wintery mix falling just at the critical decision time, 5 AM. If that occurs, districts will probably start with a 2 hour delay. If clouds remain on the light side, then obviously it is a sign the system will not make it as far north as I am alluding to here.

Just plain clouds will be reserved for northern Baltimore County as well as Carroll and Frederick Counties. Farther west in the cold valley air of the Maryland mountains, a mix of light snow and sleet is possible, with accumulations ranging less than 3”. On Saturday, plenty of cheers will be heard in the air along Harborplace as spring-a-lings celebrate with glee the end of winter, and wear shorts to prove it.

Washington: This area has a better than average chance of seeing measureable precipitation late Thursday night into early Friday morning, just enough to snarl the morning commute and make the evening ride home slick with wet roads and slippery spots. Saturday will be a wonderful day with temperatures in the mid 50’s. Go take a stroll along the Reflecting Pool in front of the Lincoln Memorial, and see how many crocuses you can spot, as this promises to be a popular spectator sport in the warm weather.

Western Maryland-West Virginia: Appears more likely this region will also see frozen precip on Thursday night, as one piece of energy from the Gulf system is moving northeast on the west side of the Appalachians. With cold air trapped in the valleys, and warm moisture over-running it at upper levels, freezing drizzle and light snow is the most likely result, accumulating perhaps 2” in higher elevations.

Southwest Virginia: Winter Storm Watches and Snow Advisories abound from Charlottesville south and southwest into North Carolina. The expectation is that enough cold dry air is present at these elevations to produce higher snow ratios, perhaps 10:1, which would translate into a general 3-5 inches for this area, up to 6” in the mountains. For hardy mountain folk, this really is not a big deal, just to us forecasters.

Western North Carolina: Winter Storm Watches abound in North Carolina, and SW Virginia will see Winter Weather Advisories as cold surface air allows most precip to fall as snow or mixed with sleet along from Fayetteville to Henderson and westward into the mountains. Accumulations will range less than 3” east of the mountains, 3-6” in higher elevations. Although there is considerable moisture, the snow ratios are very low, perhaps 6:1 or 8:1 at most, due to relatively warmer air at upper levels where the snow forms.


Weekend: Departing Ocean storm is replaced with sunshine, blue skies, temps in 40's-50’s.
Mon-Tue: Above normal temps continue, with increasing clouds and southwest winds.
Tue-Wed: Cold front and low pressure trough sweep to East Coast, ushering in Arctic air
Wed-Thu: Northern and southern streams begin to phase, setup begins for major winter storm
(Kahuna 1) to develop for the Northeast in February 10-11 period.
Sat 2/12-Mon 2/14: Brief quiet period following Kahuna 1. Temperatures near normal,
Tue 2/15-Wed 2/16: Another cold, stormy period to be highlighted by Kahuna 2
Feb 17-22: Brief moderating trend, followed by another period of cold, stormy weather to end the month.


1. The NAO. The westward OSCILLATION of the Azores High and the Icelandic Low wreak havoc with weather and computer models this time of the year. Thus, your above normal temperatures and hap-hazard winter storms thus far will be coming to a swift end the middle of next week for the entire Northeast. The positive NAO means pressure systems in the North Atlantic were too far out to sea and allowed storms to move out quickly, including the Jan 22-23 storm. Had the NAO already been strongly negative, that storm would have been the Big Kahuna. Other key factors that line up with the NAO to deliver big storms are the PNA and AO. (Pacific North American Teleconnection, and the Arctic Oscillation).

When the PNA trends positive, (which is forecasted to do around the time of Kahuna 1, it indicates that the High pressure ridge in the west will remain in place, allowing for a return to northwest flow of cold air out of Canada, into the Great Plains, Ohio Valley and Northeast. When the Arctic Oscillation trends negative, (which is also forecasted to do around the 10th) it generally means a large reserve of cold air is available and heading south. As of Wednesday afternoon, the NAO has trended back to neutral, which is in line with expectations for the weekend and early next week… no major storms on the East Coast and a brief period of normal or above temperatures. Unlike December where the entire month had a strongly positive NAO. So the telltale sign will be if we see the NAO take a huge nosedive around Feb 8, signaling the development a major event on the East Coast about 2 days later. This is the basis of my early to mid February forecast. Overall, the more negative the NAO index becomes, the more intense our Nor'easters are going to be.

2. False warmups. While it is tempting to think that the nice sunny days now mean that winter is over, I remind you that February is climatologically the snowiest month of the year. Spring-a-lings (that's the springtime version of a powderhound) will be dancing in the streets, posting comments every hour on the hour about how winter is over, I am a buffoon and should give up forecasting altogether, etc. I remind you that a false warmup now in the face of a strongly negative NAO... is like putting a big creamy chocolate cake in front of a toddler, walking away and hoping everything will turn out OK. Letting the warm air build now simply blocks cold air in Canada, and allows IT to build up as well. Once the dam breaks, look out below. The second half of February from the 10th forward will be very cold, very stormy and you'll be writing back to me saying, "Wow, I never thought it could get this cold." OR "When did you predict all this cold weather and storms, it came out of the blue!"

3. When is the Big Kahuna? I predict 2 major snow events for the Mid-Atlantic and Northeast between February 8 and 20. It will be a busy and tiring time. The false warmup will burn itself out by next Tuesday, then the winter retaliation begins. Accuweather sees this pattern taking us to the end of the month. You are noticing in your local 7 day outlooks how the warmup is being pushed back from Saturday into Sunday, then into Monday. In Boston I now see that medium-range temperatures have trended downward quite a bit, just barely 40 through Monday. With a new Arctic high forecasted to head southeast by next Tuesday, it is only a matter of time before the clash of systems begins.

As for snowfall predictions... A "Big Kahuna" in my book is defined as a large, crippling snowstorm that buries a wide area of the Northeast with 1-2 feet of snow. As Charleton Heston says in Armaggedon.. "It happened before, it will happen again, it's just a question of when." And now you have the answer to your question... the setup for this pattern BEGINS the MIDDLE of next week.


I realize that for powderhounds everywhere, it has been a frustrating winter thus far. The January snows will be a distant memory in Boston by Saturday, or just small piles of brown muck. But you have to remember that it takes the atmosphere a good while to a certain pattern in place, especially a prolonged period of cold, stormy weather in order to deliver big classic snowstorms. I know it also seems that all I do is keep pushing back the arrival time of the next big storm to the point that winter ends and it never arrives. That is not the mission of this website. My charge is to forecast long range patterns, snowstorms and hurricanes. I do extensive research on my own time into long range patterns and signals of change in the atmosphere. It's my passion this time of the year. TV forecasters spend a greater amount of time preparing their forecasts, but for the immediate term of 5-7 days.

When I see the signs of a storm brewing, all focus goes to that event, and a multi-day analysis of what may or may not happen. Having done the research into the pattern changes already, I have a general sense of what the storm will or won't do. Sometimes the long range call is off by a day or two, but when I "smell snow" in the long range pattern, I am going to tell you I smell snow. But it is up to you to decide if my analysis has merit, or express healthy scientific skepticism and research it yourself, or just consider it all hogwash and walk away. The aim is always to give you the science behind the forecast, and not just throw out a rumor of a storm because I have a hunch. That's called Farmer's Almanac Forecasting, and honestly, I have not even read it so I have no idea what it is saying. You can be sure that ANY forecast I post is grounded squarely on my research into highly complex computer modeling, and my 20 years of studying and forecasting weather.

For example...the rain forecasted for next Wednesday in Boston is probably not going to materialize, or be snow/freezing rain etc when it does. This is not a hunch, this is a forecast based on how I know the computer models behave during pattern changes. Why do I know this? Because I understand how the pattern is changing, and it is a simple meteorological fact that if the NAO has already hit neutral, it's natural trend THIS TIME OF YEAR is to head back down negative. Arctic Air does not like to remain locked in Canada in the dead middle of winter. The balance of heat and cold HAS to be maintained in order for Earth to progress through the seasonal cycle in some orderly fashion. So the end result is that the pooling cold air dives southward in several big pulses to correct the abnormal warmth which will develop this weekend and early next week.

The storms I described earlier in the week are still on the table. Storm 2 is in the Atlantic , growing larger by the hour, and the fringe of it is heading for New England. Storm 3A is coming out of the Gulf and Storm 3B will develop along the Virginia capes in a very unusual hybrid kind of upper level coastal situation.

Storm 4 is actually Big Kahuna 1, and hence will be referred to that for the remainder of February. The numbering of the storms was to represent how many systems can be connected to a particular pattern. This “hap-hazard” pattern of hit and miss storms is coming to a close, and will terminate with whatever Storm 2, 3A and 3B end up doing. The quiet period to follow from Friday to Tuesday is the prelude to the Kahuna pattern…. All storms all the time for a period of 10-14 days. If I am totally wrong and no storms materialize, I will be the first to admit I misread the pattern and you can throw, post or email egg to my face. The weather will do what it wants and is going to continue surprising or disappointing with it's complexities.

In closing this Philosophy section, I want to say that I thoroughly enjoy reading all of your comments and observations, and read them aloud to my wife each afternoon after school. Your input gives everyone a window into real perspectives of real people, and helps to continue refining and improving my storm forecasts so as to better serve you, the Meteorological Aficionado. Just be willing to take the good with the bad, otherwise the weather, and the forecasts, can get ugly!

No comments: