WEDNESDAY MAY 3, 2006
Today is national wordsmith day. Media meteorologists have the responsibility of distilling extensive quantities of atmospheric information in a mode that promotes appropriate decision making by recipients of the dispensed prognoses. This is especially important in these times when mixed media messages can cause misconceptions.
If our message has insufficient clarity for this endeavor; if the end user is somehow encumbered from exhibiting the warranted response to the expected meteorological circumstances, it may well be implied with impunity that the forecaster failed in her or his objective of assisting others in mitigating or forestalling the potential adverse effects that might have been postulated for the circumstances described. If we do not communicate with clarity, people do not have the opportunity to acquire knowledge and insight that would otherwise be useful to them.
Today's circumstance provides ample opportunity to demonstrate potential communicative inadequacies and to further promulgate the exigencies inherent in this nexus. The mere juxtaposition of expository statements and peripheral explanations does not in and of itself constitute the basis for asserting that utilitarian information is indeed being transferred. Moreover, it is suggested that excessive verbiage in no trivial way inhibits effective transfer and thereby perpetuates inadequate or inappropriate public response in terms of measures that might otherwise have been undertaken.
Today's weather forecast is a case in point. Analysis of the pertinent temporal series shows complex set of weak to moderate positive and negative vertical motion centers, each associated with patches of clear sky or areas of showers as the situation dictates. There are scattered showers and a few thunderstorms from the Midwest into the Ohio Valley and central Appalachians.
In contrast, the retrogressive cyclonic synoptic circulation that caused rain to spread westward across New England yesterday continues today. This means periods of rain and drizzle from Connecticut to Maine.
In the area dominated by neither the New England cyclonic system nor the nebulous assortment of scattered showers and clear patches farther west and south, dry weather prevails. With a mix of clouds and sun, afternoon temperatures will reach the 70s today and tomorrow across much of New York and Pennsylvania. It's just that simple. Why waste words? Why add verbiage?
Looking ahead to the weekend, there are strong indications that the Great Lakes and then the Northeast will experience the widespread negative vertical motions common in largescale anticyclonic synoptic situations. The correspondence between divergent horizontal components of the mean vectors and negative vertical mass transport is unequivocal. The resultant adiabatic heating in the absence of moist inflow unmistakably leads to the conclusion that precipitation should not be anticipated. In short, we have a high pressure area so it won't rain. However, since the anticyclonic region origin is to our north, it follows that subnormal thermal expectations are justified. This clearly suggests augmentation of normal anthropogenic thermal reserves will be essential during the nights and mornings. The negative implications of inadequate response in this regard are thoroughly familiar. You feel cold. Basically, the weather should become cool and dry during the weekend ... it's just that simple.
TUESDAY MAY 2, 2006 10:30 AM
The picture below shows the unusual juxtaposition of two storm systems. The one over eastern New England and the western Atlantic has been expanding and backing northwestward, while system in the Ohio Valley has been moving east.
In order to get cloudiness and precipitation in those storm systems, air needs to rise. As it rises, it cools, and accommodates less water in its vapor form. Saturation occurs, and if the precipitation forming process proceeds you get clouds and rain. In contrast, note the area between the two storm circulations. It is almost totally clear in that area, so the opposite process must be occurring. The air sinks, warms and becomes relatively dry. This accounts for the clearing.
My video today shows a sequence of prediction maps from the NAM-WRF model, a numerical model that is undergoing continued testing and improvement in anticipation of its role as a key operational forecast model for the National Weather Service starting this summer. In the video, I show how the model suggests the damp weather continues through tomorrow in eastern and central New England. It shows the band of showers and thunderstorms now in the Ohio Valley weakening and becoming less organized as it heads eastward.
Now, take a look at the satellite picture again. Note the swirl of clouds over Montana and the band of showers and thunderstorms running north-south through the Plains. I know these directional references can be confusing sometimes. After all, I just wrote about a band of showers and thunderstorms running north-south, but in actuality the band is moving from west to east. You can see all the cloud movements by looking at a satellite picture animation. Pro subscribers can use the link below. You can also access an animation by navigating through the satellite picture selections on the free accuweather.com site.
The Plains states band should reach the Middle Atlantic region on Thursday or Thursday night and could trigger a shower or thunderstorm most anywhere. Some models suggest the cool front represented by those showers will stall after it goes by, and then a new low pressure area could form along it. Such a storm could bring rain to the East Coast as we go through the coming weekend.
One final picture may be of interest today. In the dry zone between the two rain areas, fire danger has become critical. One developed in the mountainous terrain about 15 miles east of our house yesterday. As the fire grew, easterly winds pulled a pall of smoke through much of the area. The wind became moore northeasterly last evening, and the smoke could be seen pluming from left to right as seen from our front yard around 7 p.m. Here is that shot:Report a Typo