ISN'T IT LOVELY?
LIKE THE GOOD OLD DAYS OF JANUARY...
UNTIL WINTER RETURNS NEXT WEEK,
JUST IN TIME FOR SPRING!
UNINTENDED BENEFITS OF AN EARLIER DAYLIGHT SAVING:
* An extra hour of daylight to do your pre-garden prep work in the nice warm weather.
* If there's a late season storm, you'll also have more daylight to shovel or sled!
EXECUTIVE SUMMARY: Concensus has been growing among
public and
private forecasting agencies as well as through model indications that the period March 16 - 24 looks to be very stormy, potentially snowy and progressively colder for a majority of the East Coast. The "
false warmup" that arrived Saturday the 10th and continues into Wednesday, though very pleasant, will set the stage for a 7-10 day series of late season cold blasts interspersed with winter storms. Oddly enough, those storms might even occur OUTSIDE astronomical winter (on or after March 21) and could potentially deliver to the central Mid-Atlantic and coastal Northeast their largest accumulations of the year. The period of Sunday the 18th through Friday the 23rd may be very cold and disruptive, and temperature records may be challenged for areas which just recently observed all time lows for the month of March.
REGIONAL SUMMARY
- Ohio Valley and Great Lakes: Warmth early in the week will lead to this area becoming the battleground zone to be sure for the period 14th to 24th, alternating between rain and mild / snow, windy and colder with the passing of possibly three distinct systems over this time.
- Mid-Atlantic: Later in the week, interior and Appalachian areas will see changeovers to snow in frontal passages, then a turn to colder, while coastal areas end up with rain changing to snow for a brief time, then much colder with a possible storm around the Equinox.
- Northeast: The warmup will be shortened by arrival of the first system in midweek, followed by progressively colder and windier conditions. Snow is possible one day late next week, much colder following next weekend with the potential for a coastal system around the Equinox.
SYNOPSIS OF STORM EVOLUTION AND DYNAMICS
This discussion will contain a considerable number of computer model maps to illustrate the situation to unfold over the next 7 to 10 days. I do want to say that while long range computer model projections are not to be taken 100% literally, they do give us an indication of what pattern changes may be in development. Granted all the maps I have included will change numerous times between now and onset of the event. However I feel confident that the upper level dynamics in place strongly point to a significant late season disruption of the normal climatic pattern of gradual warming we have come to expect for this time of year. The changes being presented starting late next week will be unwelcome for many who are looking to put this winter behind them and move on to Spring.
Premise of the forecast: The false warmup from Sunday to Wednesday sets the stage for a cold, stormy and snowy period starting the 16th and continuing for a 7 t0 10 day period. Factors that will lead to the development of this pattern, in chronological order are: (1) Activation of the Southern Jet Stream; then (2) Buckling of the Polar Jet; followed by (3) Arrival of new Clippers; and finally (4) Moderating first High leads to stronger and colder second High and possible "pattern-ending" snowstorm to usher in the Spring Equinox.
1. Activation of the Southern Jet Stream due to a surface Low and upper level low in Texas that moves slowly across the southeast, allowing warm moist air to surge into the Northeast. The early and mid-week warmup across a large part of the Eastern U.S., will see temperatures climbing into the 60's and 70's to even near 80 across the Mid-Atlantic with overnight lows well above freezing. Consider the Saturday 3/10 late afternoon temperatures across Mexico, the US and Canada. Early evidence of my theorized pattern change is the slug of warmth pushing across the Baja and into Texas. Warm air coming across the subtropical Eastern Pacific means there's going to be more moisture becoming available for the next system that moves into the Gulf towards the end of this coming week.

2. Buckling of the Polar Jet. Although warmth will have overspread much of the country by Tuesday, it will exit as quickly as it arrived by end of the week. A vigorous low moving through central Canada as shown in the European projection below will provide additional strength to the warm air advection. However it's counter-clockwise flow on the backside will be the first domino to fall and initiate a surge of cold air along the first in a series of clippers to cross the Great Lakes and Ohio Valley into the Northeast. This buckling of the polar jet will lead to the demise of the weak cross-continental "zonal flow" before it has time to help establish a warmer regime.

Concurrently, an upper level and surface low is projected to be moving from Texas to the Southeast during this time period. Upper level lows are notorious for moving slowly, thus allowing the surface low to tap and enhance moisture transport from the Gulf into the Tennessee and Ohio Valleys in advance of the progressing cold front. This is indicated by
current QPF projections as well as by the GFS surface projection for Wednesday the 14th. Note that with each passing day this week, these links will automatically update with the most current changes as progged by government forecasters at NCEP.

3. Arrival of "Clippers" turned "Coastals." This first Great Lakes clipper will usher in a strong cold front through the Mid-Atlantic and Northeast on Thursday and possibly as early as Wednesday. Rain that starts along I-95 on either day may even change over to snow for a brief period before the day ends, and interior sections of Maryland, central/western Pennsylvania may end up with a few inches of wet snow as the front passes overnight Wednesday or Thursday. This trend has already begun in
local forecast grids from NWS offices in State College, PA.

Behind this front will be the first in a series of cold surges to plunge into the Northeast starting on Friday the 16th, followed by a second and colder Arctic High Sunday into Monday. Temperatures by Sunday the 18th across much of the eastern 1/3 of the nation may be 10-15 degrees below normal, which is to say if you're in Philadelphia, an average high right now is roughly 50*F. Using Accuweather's 6-10 day outlook for example,
by next Sunday you may be looking at highs in the upper 30's to low 40's and lows once again in the 20's.
4. Moderation of the first Arctic high by Tuesday the 20th ushers in more moisture from the Gulf, which may lead to a stationary frontal boundary between a warm moist air mass in the Southeast and the incoming Arctic Highs. Several weak areas of low pressure may develop along this front, transporting precipitation from the Gulf into the Tennessee and Ohio Valley and eventually into the Mid-Atlantic..as indicated on the map below. Of course, this is a 10 day outlook and those of you skeptical about this verifying are rightly so. I'm showing this just as one piece of an overall larger picture of the pattern evolution.

While I agree with skeptics that precise forecasts more than 10 days out are haphazard at best, it remains to be argued that if unseasonably cold air is firmly in place across the Northeast, it is probable that one or more systems moving from the Gulf may eventually result in interaction between the southern and northern branches of the jet stream. Some indication of this scenario is revealed on the GFS projection for Wed 3/21 and Thu 3/22. Whatever precipitation falls on your home, whether it is rain or snow during this event, re-freezing is possible given the arrival of a second very strong and cold Arctic High following the 21st and 22nd. This last stage of cold in the 16th-24th period may reach it's maximum intensity by the weekend of the 23rd, especially if widespread snowcover has been established prior to the arrival of this final Arctic High. Keep in mind it would take a few days to melt this snowcover, even in the strong March sun, when overnight lows dip enough to refreeze until the pattern moderates after the 24th.

In conclusion, consider the following interest groups and impacts which may result from this upcoming weather pattern (extended period of storminess and cold weather)
- If you're a school administrator or department chair, what formal observations planned for the period 16th to 24th? Are these reschedules from earlier weather-related interruptions? Perhaps if you need to fit in an emergency drill or bus evacuation before the month is out, this upcoming week of nice weather might be the opportune time to do it?
- If you're an Athletic Director or Coach, I'm certain you have scrimmages or even early season games scheduled for this time. Realize that this pattern described would most certainly render field use, games and outdoor practices infeasible from Thursday the 15th to Sunday the 24th. What plans or schedule adjustments could be made in the coming week to compensate?
- If you're a landscape or outdoor-related business owner, how might this unwelcome late season weather affect your sales? What will you do to counter a week or more of bad weather when consumers aren't likely to be buying up spring supplies.
- If you work at an Elementary school or daycare center, (both of which I did once long ago), you know the impact to your sanity caused by having to keep the children for indoor recess for an extended period (7-10 days), especially if there's a combination of cold, snow, rain and wind.
- If you're an avid outdoor and gardening person like me, I don't want to see "Breaking News" on CNN: Gardener freezes to death in backyard attempting to keep recently planted bushes alive with body heat. I'm sure Home Depot and Nurseries will be inticing you will all kinds of wonderful things to plant in your yard, but DON'T DO IT THIS WEEK!
When time permits this coming week, I will be adding suporting links within the text, modifying the analysis and including the March 1956 storm analog complete with maps and side-by-side comparison to what's coming. Take advantage of the unique combination this week of more daylight afforded to you by the U.S. Congress, and the brief warm spell provided by Mother Nature. It'll be a nice respite from the recent cold and a promise that help is indeed on the way once we get past this final round of nastiness.