Weather

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Area forecast discussion 
National Weather Service Wakefield Virginia 
154 PM EDT sun Sep 7 2008 


Synopsis... 
a frontal boundary becomes nearly stationary across North Carolina 
today. Meanwhile...high pressure builds into the middle Atlantic 
region through Monday. A stronger cold front crosses the region 
late Tuesday. High pressure builds into the region Wednesday. 


&& 


Near term /until 6 PM this evening/... 
Hanna continues to move rapidly NE and away from region this am. Trailing 
frontal boundary prognosticated to become nearly stationary across NC through Monday. 


In shortest of terms...will carry patchy fog through 12z or so in 
grids due to combo of wet grnd as winds have decoupled in areas 
away from the water. Trplcl airmass in place today in wake of Hanna. 
Tsctns sprt a M sunny day ahead with temperatures in M-u80s. 


&& 


Short term /6 PM this evening through Tuesday night/... 
500 mb ridge builds into region through Monday night with stalled frontal boundary 
lingering across NC. Models do show some moisture dvlpng along this 
boundary Monday. Although an isolated shower is possible ivof Albemarle sand Monday 
afternoon...will keep probability of precipitation out of forecast at this time as it appears that any 
convection that does develop gnrly stays S of Albemarle sand. As last 
shift indctd...models continue to show ptnt sea breeze boundaries dvlpng 
drng peak htng hours. However...not enough evidence to include any 
probability of precipitation in forecast at this time. Lows tonite mainly in the 60s...xcpt 50 ivof 
sby. Highs Monday M-u80s. 


Moisture begins to increases across forecast area Monday night out ahead of next frontal 
boundary apprchg from the west. Will keep it dry Monday night but indct an 
increases in cloud cover...spclly across western counties. Lows in the 60s. 


Decent agreement to sprt chance probability of precipitation (shwrs/tstrms) out ahead of cdfrnt 
Tuesday with said frontal passage Tuesday night. Highs Tuesday in the m80s. 


&& 


Long term /Wednesday through Saturday/... 
GFS/European model (ecmwf) remain in decent agreement and continue to show the cold 
front stalling across the Carolinas on Wednesday as the middle level flow 
flattens out. Will have 30% chances of precipitation across the south tapered 
to dry forecast north. With north-northeast flow highs should remain in the upper 
70s. 


Difficult forecast Thursday/Fri/Sat as eventual track of Ike will be the 
dominant feature. Overall best chances for showers would be SW zones 
west/ low level Ely flow as weak warm advection begins to move back in 
the low/middle levels from the SW. Will keep current forecast as is for now... 
but if latest trends hold true...precipitation chances will likely be dropped as 
dry and cooler airmass remains across region. 


&& 


Aviation /18z Sunday through Friday/... 
VFR conds across the region today with light downsloping (westerly) winds 
and high pressure in place. 


Expect another night of patchy fog tonight/Monday morning with 
soil moisture remaining high and winds once again decoupling 
after sunset. Look for full VFR conditions during the day on 
Monday. Chance of precipitation then increases through the day Tuesday ahead 
of approaching cold front...with frontal passage early Wednesday. High pressure 
will then return by late Wednesday through Thursday. 


&& 


Marine... 
Hanna has transitioned to an extratropical storm and it continues to 
race farther away from the area towards the Canadian Maritimes with 
high pressure building in across the waters today. Small Craft 
Advisory has been cancelled for southern waters from Parramore Island Virginia S 
to Currituck Beach Light NC with buoy observation showing seas between 3 
to 4 feet. Could still have an occasional 5 feet lingering wave or two 
mixed in outer portion this am...although sig wave height will 
remain below Small Craft Advisory criteria. Extended Small Craft Advisory flags north of Parramore Island 
Virginia through 4 PM EDT as seas are still running at or above 5 feet in those 
areas. 


Winds over the waters will be primarily diurnally driven today 
as high pressure moves overhead. Light offshore winds this am 
will become onshore early this afternoon as a seabreeze develops 
and pushes inland. The high will then move offshore on Monday with 
flow turning back to the S/SW ahead of the next cold front...which 
will move through the region on Tuesday. Models then indicate a possible 
Small Craft Advisory northerly wind surge later Tuesday into Wednesday behind the cold 
front...although this will be dependent on how much cold air actually 
gets advected into our region. 


&& 


Rip currents... 
lingering swell from former tropical system Hanna will slowly 
subside today. Waves in the surf zone will average between 3 to 4 feet 
this morning...then 2 to 3 feet by the afternoon. Forecast a moderate 
risk of rip currents at Maryland/VA/NC today vs a high risk as tidal 
anomalies will be low...and as winds will be predominantly 
offshore. 


A moderate risk of rip currents means wind and or wave conditions 
support stronger or more frequent rip currents. Only experienced 
surf swimmers should enter the water. Be especially cautious with 
outgoing tides which improve rip current formation. 


&& 


Hydrology... 
Hanna brought some beneficial rainfall to region. Total rain amounts 
ranged from 1 to 3 inches east of I-95 (lcly higher amounts across 
portions of lower Maryland eastern shore)...with amounts between 2 to 4 inches 
over most areas west of I-95. Pockets of 5-7" amounts were noted over 
portions of the eastern Virginia Piedmont...with radar estimates near 8" over 
far western Prince Edward County. 


However...some flooding prblms. Only Flood Warning at this time is on the 
Appomattox above Farmville where the river is (at 1 PM edt) at 
16.9 feet (flood stage is 16.0 ft) with a crest this evening near 18 
feet. See latest flsakq for details. At 1pm...the Meherrin River at 
Lawrenceville was 13.6 feet (flood stage 15.0 ft) and still rising 
though it is expected to remain below flood stage with a crest 
this afternoon. No othr flooding xptd at this time with modest rises 
across the area. 


&& 


Akq watches/warnings/advisories... 
Maryland...none. 
NC...none. 
Virginia...none. 
Marine...Small Craft Advisory until 4 PM EDT this afternoon for anz650- 
652. 


&& 


$$ 
Synopsis...mpr 
near term...mpr 
short term...mpr 
long term...lkb/mpr 
aviation...baj/jrl 
marine...jrl/baj 
rip currents...jrl/baj 
hydrology...mpr/baj 

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