11PM ISAAC RUN-DOWN ...

I'll try and do this periodically as we watch this thing unfold. But until the storm establishes a true inner core (which should happen in a day or two), there's no telling where this is going and how strong it will be. But the odds of a US miss are slim based on most sources and the overall pattern in the atlantic (see previous post, as i use TWC graphics to show what's going on in the larger sense).

ISAAC TO BECOME A HURRICANE: IMPACT TO US COAST VERY LIKELY EARLY NEXT WEEK

VIDEO: LOOKING AT THE "PROBLEMS" FOR THE WEEK

PREDICTABILITY OF FORECAST PERIOD LOWERED TO MEDIUM NOW THROUGH
WEDNESDAY, HIGH FOR WEDNESDAY THROUGH SATURDAY.




"weather overview" terms to help kick the point-and-click:

PREDICTABILITY OF FORECAST PERIODS

HIGH- most credible sources are in excellent agreement
MEDIUM: most credible sources are in fairly good agreement, with some differences
LOW: widespread differences in forecasts, AND overall low confidence from NWS Upton office

Risk of a shower/thunderstorm-probability of a shower is low. Most of the forecast period will be dry.

Numerous (heavy can be inserted) Showers/thunderstorms- probability of showers is high, and could happen multiple times during the given forecast period. Constant rain is not expected

Rainy conditions-intermittent precip; rain can vary in duration, but usually will last more than an hour. Light to moderate intensity. Less than an inch expected during the forecast period.

Heavy Rain-soaking, constant rainfall for at least an hour (duration can be much longer); amounts over a half an inch. 

Light snow-very light snowfall. Little to no accumulation. Duration depends. 

Snowy conditions-intermittent snow can last more than an hour at a time, but generally average less than 3 inches total.

Heavy Snow-heavy snowfall. Snowfall of at least 3 hours in duration. Totals can be added in

Drizzle-constant drizzle

Occasional Drizzle-intermittent drizzle

A PERIOD OF TRANQUIL AUGUST WEATHER SHAPING UP FOR SUNDAY THROUGH FRIDAY

PREDICTABILITY OF FORECAST PERIOD FROM MONDAY-FRIDAY-HIGH

 

A change in the overall pattern will put a lid on the frequent bouts of showers and storms that we’ve been experiencing the past ten days. In fact, a lot of areas will not see much if any rainfall through about Friday of next week. Temps will be kept to near normal levels, as the robust heat pump, which originated from the Southern Plains States for much of late June and July, has essentially been wiped out.

GFS 7-DAY "MEAN" TEMP SHOWS COOL OVER THE PLAINS (Ewall Site)

 And because of the newly configured pattern, air masses which spread over us will have modest humidity values. 

INTELLICAST TEMPS:

INTELLICAST PRECIP

NOAA TEMPS

NOAA DEW POINT chart shows very comfortable values mid-to-late week:

 Lurking in the distance however will be the increasing rumblings from the tropics. The typical peak of the season will begin, and with it, a renewed burst of activity both well out in the Atlantic and in close to our continent will commence.

Overall, the pattern can try to pull in storms that come close to the eastern seaboard, but this scenario is not likely to unfold in any meaningful way until after the 25^th.

DODGING SOME MID-WEEK STORMS THIS WEEK

PREDICTABILITY OF FORECAST PERIOD REMAINS MEDIUM THROUGH MONDAY

1. Dismal performance by the last overview, as timing of rain fell apart with the first wave coming last Friday around midday, then virtually no precip after! Only consolation was that rainfall amounts verified with torrential downpours this past Friday. Confirmed tornado touched down in Suffolk County Friday afternoon.

2. Humidity increases tomorrow, with showers and storms for areas west of NYC during the afternoon. First batch of storms will dissipate before reaching NYC in the early evening. NYC points east may not see a drop of rain until well into the evening/overnight.

NOAA has west of NYC in a greater risk for severe storms tomorrow as does Accuweather

3. Activity will become numerous for a period between 10pm Tuesday and 10am Wednesday for most spots. Heavy rain/storms, then becoming more scattered/isolated after noontime under a canopy of cloudiness. Continued muggy.

4. Thursday, another break from storms and high humidity, but then things will fire up Friday late afternoon west of NYC. Once again, storms will wait to penetrate the NYC region/points east until after dark. Showers will be numerous into Saturday morning. Weekend will be dominated by clouds, but rain chances will be widely scattered from Saturday afternoon through late Saturday. Slow clearing Sunday.

5. TEMPS: NYC running several degrees above normal for the month so far. Projection is for near-to-slightly above normal temps through Friday, then a cool-down in temps for a few days through early next week. Another spike could come after the 24^th.

Intellicast

6.  Aside from June, every month this year has registered “above-average” in terms of the “mean” monthly temp, and August will surely follow the overwhelming trend for 2012.

HONING IN ON TOMORROW/SATURDAY RAIN

PREDICTABILITY OF FORECAST PERIOD -MEDIUM

ACTIVE PATTERN RECOMMENCES THURSDAY THROUGH SATURDAY

PREDICTABILITY OF FORECAST PERIOD THURSDAY THROUGH SATURDAY-LOW

PREDICTABILITY OF FORECAST PERIOD SUNDAY-WEDNESDAY-MEDIUM

First comes the humidity, then come the storms! The active pattern will continue, with brief interludes; that's the main story as we progress through the next 7-10 days.  it can be stated again here that few 90-degree days are in the offing through the 15th, but a turn to a warmer pattern may ensue from mid-month onward.

accuweather slide:

HIGHLIGHTS:

1. Thursday: Humidity increases in ernest. Temps come up to near 90. Muggy night thursday night.  Only a risk of a shower Thursday, especially west of NYC.

2. Friday-Saturday: Active two-day stretch, with afternoon/evening showers and heavy thunderstorms (numerous). There can be periods of steady rainfall lasting more than an hour, especially overnight Friday/early Saturday. storms east of NYC will linger through midday Saturday, then some slow, partial clearing. 

3. Just like this past weekend, bigger "severe" storm threat west of NYC, while flooding the main threat over LI/CT.

Intellicast Temps:

4. Sunday and Monday, a temporary break from the possibility of showers and storms. However, humidity and storminess return for at least Tuesday and Wednesday and possibly beyond.