DATE: Friday, October 17, 1997              TAG: 9710170650

SECTION: LOCAL                   PAGE: B5   EDITION: FINAL 

SOURCE: BY STEVE STONE, STAFF WRITER 

                                            LENGTH:   69 lines

FLOODING, EROSION POSSIBLE ON WEEKEND, THANKS TO THE MOON

While rain is in store for Hampton Roads through Monday, a threat of coastal flooding this weekend can be blamed in part on something far removed from the storm clouds: the moon.

Minor flooding is possible today along the Virginia coast and the northern Outer Banks of North Carolina, the National Weather Service said Thursday, with more significant flooding and some beach erosion possible over the weekend.

A confluence of earthly weather events and the gravitational effects of the recent full moon are making it all possible.

``Strong high pressure over the Great Lakes region, coupled with developing low pressure along the southeast coast, will produce a prolonged period of onshore winds along the mid-Atlantic coast through this weekend,'' said Bryan Cullen, a meteorologist at the weather service office in Wakefield.

High-pressure systems rotate clockwise, while lows - storms - rotate counter-clockwise. Thus, where the two meet, an egg-beater effect makes for strong winds. Put that pattern over Hampton Roads and winds blowing out of the east push up higher tides along the coast.

``In addition, astronomical tides are running high due to the recent full moon,'' Cullen said.

Tides of 1 to 1 1/2 feet above normal are expected today, especially this morning, when the astronomical tide is the highest.

By Saturday, onshore winds are expected to increase as the developing northeaster moves slowly northward. Rough surf also may cause some beach erosion this weekend.

The weather service said a coastal flood watch may be issued today if the potential for flooding this weekend seems likely.

High tides will occur today at Sewells Point in Norfolk at 10:38 a.m. and 11 p.m.

Even absent any flooding, the weather will be more suited to ducks than people for several days, as any doubts that fall is here get blown away. Wet, windy, chilly, gray weather is the rule until Tuesday.

A stalled frontal zone just offshore provided a path to carry some weak, stormy weather over the region from the south Wednesday night and Thursday. Meanwhile, the northeaster is expected to develop over northern Florida by tonight along that same frontal line and then move northeast along the Atlantic Seaboard over the weekend.

Rain is likely across much of Virginia and North Carolina today through Sunday, with thunderstorms possible along the Outer Banks tonight through Saturday night.

The rain should help lessen the region's rain shortage, however. The 0.13 inch of rain recorded by 5 p.m. at the National Weather Service office at Norfolk International Airport is the first rainfall this month. Normally, 3.41 inches falls in October.

For the year, 25.64 inches has fallen in Norfolk - almost 11 inches below normal.

Here is the Hampton Roads forecast:

Today and tonight - Periods of rain and drizzle with a high in the lower 60s, a low in the mid-50s and northeast winds at 15 to 20 mph. The chance of rain is 80 percent.

Saturday, Sunday and Monday - Rainy and becoming windy with highs in the lower 60s and overnight lows in the mid-40s to low 50s. Northeast winds will be sustained at 20 to 25 mph with higher gusts. The rain should begin to taper off Monday.

Tuesday - Clearing and cool but continued windy along the coast and east of the Chesapeake Bay. The high will be in the upper 50s to near 60 with the low between 45 and 50.

Small-craft advisories will likely be posted by tonight as northeast winds increase to 25 to 30 mph with seas building to 6 to 8 feet, the weather service said. Winds may increase to gale force Saturday night and Sunday. KEYWORDS: NORTHEASTER WEATHER EROSION

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