The Weather Shelter, August 2000

Published monthly by the North Jersey Weather Observers

Volume XVIII Number 8 August, 2000

http://njwo.tripod.com

Important Reminders:

· This months meeting is August 30^th, at 7:30 pm. Club members will meet at the Bergen County Museum of Art and Sciences.

· Please remember to send all correspondence to be printed in “The Weather Shelter” in electronic format.

· This month’s speaker will be Matt Gorgescu from the graduate meteorology program at Rutgers University.

NORTH JERSEY WEATHER OBSERVERS MEETING - Wednesday, July 26, 2000

NORTH JERSEY WEATHER OBSERVERS - MEETING - Wednesday, August 30, 2000 -

The evening was mostly cloudy and 77 degrees when the meeting was called to order at 7:58 p.m. The secretary and treasurer conducted the meeting until the president arrived. Founding member Bob Draper was introduced. He wants to become active again after being out of the area for many years. The rest of the 11 members present also introduced themselves.

We talked about recent weather events for a while, including the day of 14 inch rainfall in Sparta and a minimum of 39 degrees at another location. Each member described his home station and types of record kept.

President Keith Galley announced that he has a job interview in Elmira tomorrow. [Secretary's note: The interview was successful. Keith will be moving to Elmira, New York, shortly and working for WETM television, Channel 18, an NBC affiliate. Welcome to my state.]

Our guest speaker was Matthew Georgescu, a graduate student at Rutgers University who showed some video of conditions at the top of Mount Washington, where he spent two summers, and then described his research on numerical model forecasting.

The next meeting is Wednesday, September 27, at 7:30. The scheduled speaker is David Robinson.

Dennis O'Keefe,

Secretary

Subject: August in New Paltz

New Paltz, New York - August 2000 Summary

from Dennis O'Keefe

Average maximum: 78.4

Average minimum: 61.5

Monthly average: 70.0

High temperature: 86 on the 8th and 9th

Low temperature: 48 on the 21st

Precipitation: 3.30 inches

Seven days with fog

Four thunderstorm days

Highlights: 18 days with highs only in the 70s. 15 days with rain, with he greatest single day only 0.61.

Westwood, NJ Report - June 2000

By Tom Shaw

TEMPERATURES

Avg H: 79 High 93 (6/11)

Avg L: 60 Low 48 (6/7)

Avg monthly temp: 69 Five Days 90+

PRECIPITATION

4.56" in 12 days. 17.39” year to date

7 thunder storm days

Avg BP: 29.90

Max wind: 17 mph (6/21)

Westwood NJ Report - July 2000

By Tom Shaw

TEMPERATURES

Avg H 81 High 89(10th)

Avg L 61 Low 50(24^th)

Avg monthly temp: 71

PRECIPITATION

7.39" in 10+ days 24.78" year to date

COLORADO STATE UNIVERSITY HURRICANE FORECAST TEAM LOWERS NUMBERS BUT STILL CALLS FOR AN ACTIVE SEASON IN YEAR 2000

[NOTE: Forecast totals are in the attached chart. The complete]

[hurricane forecast and related research and related research]

[and press releases are available on the World Wide Web at:]

[http://tropical.atmos.colostate.edu/forecasts]

August 4, 2000

FORT COLLINS-Data since the official June 1 start of the 2000 hurricane season have convinced William Gray and his hurricane prediction team that this year, while active, won't be quite as bad as they had thought in early June.

In the fourth forecast and final update for the year, the Colorado State University team is calling for 11 named storms, seven hurricanes and three major hurricanes.

That's how the year started when the initial prediction was issued back in December 1999, and that's what they anticipated when their April update was issued. By June 1, however, the official beginning of the June 1-Nov 30 Atlantic Basin hurricane season, Gray and colleagues saw reason to raise the number in each category of storm by one.

They're back to 11, seven and three, due to recently observed cooler Atlantic Ocean surface water temperatures and a weakening La Nina that should not enhance Atlantic Basin hurricane formation quite as much as the team's expectations in early June. An average year during the period 1950-1990 has seen 9.3 tropical storms, 5.8 hurricanes and 2.2 major

hurricanes (those with wind speeds above 110 mph.

The fact that two months have passed without so much as a named storm is irrelevant, Gray said. Last year, a very active one, produced only one

tropical storm, Arlene, before Aug. 19, generally acknowledged as the start of the intense part of the season, and hurricane activity in 1998 also started very late.

"The fact that we haven't had an early season storm doesn't mean anything," Gray said. "There is no correlation between June and July storms and what may take place later in the season; in fact, there's some evidence for a slight negative correlation (i.e., the absence of early season storms is made up for by late-season activity)," according to Gray.

He expects the severe part of the season to occur about when it usually does, for 60 days beginning around Aug. 20 and continuing until roughly that date in October.

What led Gray, professor of atmospheric science, and his colleagues to return to their original prediction? Geophysical phenomena, what Gray

calls "climate signals," seemed ready to take an upturn based on April-May data but now have weakened to some extent.

"Sea surface temperatures in the Atlantic Basin have not warmed quite as much as expected," said Gray (the Atlantic Basin consists of the North

Atlantic, Caribbean and Gulf of Mexico). Because tropical depressions that could grow into named storms and beyond require a pool of warm water to draw energy from, and because estimates say that pool must be at least 100-150

feet deep, cooler surface water temperatures in the Atlantic could inhibit storm formation.

So, too, has La Nina slowly weakened. This mass of cold water in the equatorial eastern Pacific, when strong, produces weak westerly or even

easterly winds that promote hurricane formation. At the beginning of summer Gray and his team saw evidence that the cool water would persist, but

recent readings indicate that La Nina has slightly weakened over past weeks, making it a little less favorable for hurricane formation.

What coastal dwellers should anticipate, Gray said, is for an active hurricane season but one likely to be slightly weaker than those that

occurred in 1995, 1996, 1998 and 1999. The five years beginning in 1995 constitute the five most active consecutive years of hurricane activity in history, producing 65 named storms, 41 hurricanes and 20 major hurricanes. Gray and colleagues believe that the current upturn in storms has nothing to do with global warming but instead is a result of a stronger Atlantic

Ocean thermohaline system or Atlantic conveyor belt. Moving warm, relatively salty water to the cold seas of the North Atlantic produces a condition where the salty, hence relatively heavy, water sinks, carrying with it its warmth.

The result of a strong (warm and salty) Atlantic conveyor belt does not cause many more weaker storms, Gray said. Its main influence is to

Produce more major storms (in Saffir-Simpson categories 3-5 with wind speeds of 111 mph or higher). Such enhanced conditions existed from the late 1920s to the late 1960s, causing numerous major storms to make landfall on the U.S. Atlantic coast. This tendency has again been picking up since 1995. The periods 1900-25 and 1970-74 saw weak (i.e., relatively cool and un-salty water) in the Atlantic conveyor belt and the number of major landfalling storms during these periods were reduced from the long-term average.

Gray and his team's final forecast update for 2000 (he'll issue an assessment of the year's predictions in late November) means a lot of storms will be packed into a relatively short period of time, August-October(few storms take place in November). Last year's forecast-which did not change numbers throughout the season-was one of the most successful for the Colorado State team, who've been predicting the number and intensity of Atlantic Basin hurricanes since 1984. The team called for nine hurricanes

and 40 hurricane days. There were eight hurricanes and 43 hurricane days.

They forecast four major hurricanes and five were observed. Gray and co-authors Chris Landsea, Paul Mielke and Kenneth Berry, with the

Assistance of John Shaeffer, Todd Kimberlain, Eric Blake and Bill Thorson, use a variety of climatic factors in their forecasts. In addition to stratospheric winds, North Atlantic sea surface temperatures and La Nina-El Nino

conditions, they look at a ridge of barometric high pressure called the Azores High, warmer sea-surface temperatures throughout the Atlantic, two measures of west African rainfall and mid-latitude oceanic wind patterns in the Atlantic and Pacific oceans.

Although Gray argues strongly that the public and media talk only of the influences of La Nina and El Nino affecting hurricane activity, a number of other climate factors, such as Atlantic sea surface temperatures and surface pressure also are involved. These latter factors do note look quite as favorable as they did in early June but still more favorable than average.

"We thought we had verification that La Nina would continue relatively strong throughout the season, but it appears to be fading a little more rapidly than we expected," Gray said. "Under those circumstances, we're reducing our early June forecast numbers a little, although people should remember that there still is the possibility of this being a very active

season, especially compared with the 1970-1994 period."

Predictions continue to place the the probability of one or more major hurricanes coming ashore somewhere along the U.S. coastline from Brownsville to the Maine-Canada border at 60 percent (the long-term mean is 52 percent).

The probability of one or more major hurricanes making landfall on the U.S. East Coast, including the Florida peninsula, is 39 percent, compared with an average the past century of 31 percent. The Gulf Coast faces a 34 percent probability of facing one or more Saffir-Simpson 3-4-5 storms (the last century's average is 30 percent).

The Caribbean basin faces a possibility of landfall by one or major storms about 10 percent above the past century's average.

GRAY RESEARCH TEAM HURRICANE FORECAST

2000 SEASON

12/99 04/00 06/00 08/00

Named Storms (9.3)* 11 11 12 11

Named Storm Days (46.9) 55 55 65 55

Hurricanes (5.8) 7 7 8 7

Hurricane Days (23.7) 25 2 35 30

Intense Hurricanes (2.2)8 3 3 4 3

Intense Hurricane Days (4.7) 6 6 8 6

Hurricane Destruction Potential (70.6)**85 85 100 90

Maximum Potential Destruction (61.7) 70 70 75 70

Net Tropical Cyclone Activity (100%) 125 125 150 130

*Number in ( ) represents average year totals based on 1950-1990 data.

**Hurricane Destruction Potential measures a hurricane's potential for wind- and ocean-surge damage. Tropical Storm, Hurricane and Intense Hurricane Days are four, six-hour periods where storms attain wind

speeds appropriate to their category on the Saffir Simpson scale.

MONTHLY SUMMARY - AUGUST, 2000

KING OF PRUSSIA, PA.

August weather conditions continued a pattern established during

July: frequent precipitation, oppressive humidity and cooler than usual temperatures with no extreme heat. Temperatures averaged 72.8 degrees with only one day yielding a high of 90 or more (7th). Precipitation occurred on 20 days yet totalled below normal in King Of Prussia (3.42”). Some areas in the region received excessively higher totals due to erratic showers & thunderstorms. No severe weather occurred locally. Tropical storm/hurricane activity during the month was fairly active. There were four named storms: Alberto, Beryl, Chris & Debbie. Only Debbie posed a potential threat to the U.S. mainland. Alberto became the longest lasting storm in the month of August and the third longest on record as it meandered & looped around in the Atlantic. It became a hurricane 3 separate times during its journey.

On the 1st, light showers occurred overnight and in the evening; thunderstorms moved by to the NNW. On the 3rd into the 4th, a storm system caused heavy showers with embedded thunderstorms during the evening & overnight hours, dropping well over an inch of rain. The 5^th turned out to be an excellent summer day with abundant sunshine through deep blue sky, low humidity, an afternoon high in the low 80s and gusty North winds. It was, in fact, one of the best fair weather days of the month as well as the season.

Clouds returned on the 6th with sprinkles & some light rain occurring

early in the afternoon and again in the early evening. Hot & oppressively humid conditions prevailed on the

7th under mostly cloudy-partly sunny skies. Early in the evening a heavy, gusty thunderstorm brushed by my station area to the north. Wind gusts reached speeds of 20-30mph. The core of the storm moved through nearby Norristown where a severe thunderstorm warning had been issued.

From the 11th-14th, a stalled low pressure system along the eastern seaboard triggered the development of slow moving and stationary showers & thunderstorms on each day. Some areas in the mid Atlantic region were clobbered with heavy rains, flooding & storm damage while

others were left relatively unscathed, such as King Of Prussia. As low pressure developed over eastern Pennsylvania on the 11th, scattered thunderstoms cropped up and moved through this locality early in the

afternoon and again early in the evening. Less than 1/4 inch of rain total from both storms was measured.

On the 12th, weather conditions in King Of Prussia were mostly benign except for a mid afternoon shower with distant thunder to the ESE. Elsewhere, major storm events took place: In northwestern NJ, 10-14 inches of rain resulted in catastrophic flooding. Sparta was particularly hard hit. Heavy rain & thunderstorms occurred along western NJ as well as extreme eastern & southeastern Pennsylvania. In northern Chester county, a severe thunderstorm uprooted trees, caused property damage and dropped 1/2 inch hail. The thunderstorm was part of a cluster that looped around the area starting toward the ESE, moving by south then curving to the west. Rainfall at my station totaled 0.15”.

The 13th remained cloudy & very humid with ENE breezes. Sprinkles

occurred late in the afternoon. On the 14th, there was a period of rain with embedded thunderstorms from late morning through mid afternoon as the stalled storm system began to move northward then away from the region.

Following a typical summer day on the 15th, humidity lowered and winds turned WNW on the 16th in the wake of a cold front that moved through before dawn. A sprinkle with a distant thunder- storm to the SSW accompanied its passage. Sunshine faded behind increasing cloudiness on the 17th as another storm system arrived from the west, causing some late afternoon sprinkles. King Of Prussia established a new record low of 60 degrees. Occasional light showers occurred on the 18th and light fog developed. Temperatures were unseasonably cool an varied little, ranging from a record low of 61 to a high of 67.

The 19th-22nd were primarily sunny with pleasant afternoon temperatures in the upper 70s to the low 80s(22nd) with low humidity. A storm system produced gusty south winds and light mid afternoon showers on the 23rd. Light fog developed in the evening. On the 24th, cloudiness & a sprinkle gave way to partial sunshine and humid conditions. Fair weather prevailed on the 25th & 26th.

From the 27th-31st, clouds and high humidity dominated and scattered light rain, showers & thunderstorms developed occasionally. Stalled low pressure along the eastern seaboard that retrograded westward turned winds to the ENE while creating muggy, humid conditions. On the 27th, thunderstorms developed around this locality during the late afternoon & evening. Light rain from a nearby thunderstorm centered to the east late in the evening provided 0.16”. A period of steady rain occurred the morning of the 31st.

Observer: Michael Cerio

Station: King Of Prussia, Pa.

County: Montgomery

Elevation: 185’

Next Meeting Date:

August 30, 2000 - 7:30 p.m. - Bergen County Museum of Art and Science

Year 2000 Schedule:

Unless otherwise notified - Last Wednesday of every month. Guests are welcome. Please mark these dates on your calendar and see if you can make it!

NJWO Membership Dues:

$25 a year / $15 for students.

Officers and Committee Chairs:

President: Keith Galley 732-247-5256