Area Forecast Discussion
Issued by NWS Columbia, SC

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000 FXUS62 KCAE 190738 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 338 AM EDT Sat Oct 19 2019 .SYNOPSIS...
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Tropical Storm Nestor will move inland over the Florida Panhandle this morning, move across Georgia this evening then cross eastern South Carolina tonight as it becomes a post-tropical cyclone. The system will bring potentially significant rainfall to the area along with windy conditions. A brief break in the weather is expected Monday followed by another cold front crossing the area Tuesday.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Mid level clouds will begin increasing across the area this morning and lowering as the air mass moistens with the approach of Tropical Storm Nestor. Rain showers will move into the CSRA this morning, but onset of any rainfall may be delayed slightly due to the drier air currently in place. The center of Nestor is expected to track across Southern Georgia through the day today and then across the Midlands this evening as it transitions into a post-tropical low. This system will bring significant rainfall along with windy conditions, with the greatest impacts later this afternoon and evening. With peak precipitable water values exceeding 2 inches and a deep warm layer aloft fueling high rainfall rates, expect rainfall totals around 2 inches across the northern Midlands to near 3 inches in the south. The system will be progressive which should limit the flood threat, but there is the possibility of higher amounts with localized flooding due to runoff. Instability should remain limited because of widespread rain and a lack of time for the development of significant surface-based destabilization because of the fast system movement, but wind shear will be high so cannot rule out a few stronger cells with a marginal threat of tornadoes, especially across the eastern Midlands. A model blend supports most likely peak wind gusts 30 to 40 mph, mainly in the southern CSRA and east. There is some concern of stronger wind because of the accelerating storm movement and some possibility of greater instability, but based on the forecast storm track with the greater instability forecast to stay well east of the forecast area believe this threat is low. However, a Lake Wind Advisory has been issued due with the expectation of frequent gusts greater than 25 kts.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
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Post Tropical Storm Nestor is forecast to cross southeast GA and the Coastal Plain of SC tonight then move off the NC coast Sunday. This system will bring significant rainfall along with breezy conditions. Categorical pops in order tonight as the system crosses eastern SC. Precipitation should lift northeast of the Midlands during the early morning hours Sunday. The models depict strong lift associated with a 40-knot southeast h85 jet and negative tilt h5 shortwave trough. A model blend supports general rain totals of 1.5 to 2.0 inches in the Piedmont to 2 to 3 inches in the eastern Midlands and lower Central Savannah River Area. The system will be progressive which should limit the flood threat. Precipitable water forecast to exceed 2 inches so there may be high rainfall rates with some possibility of localized flooding. Instability should remain limited because of widespread rain and a lack of time for the development of significant surface- based destabilization because of the fast system movement. The models keep surface-based LI values above zero except possibly in the extreme east part where both the GFS and NAM show values near -1 this evening. Shear will be high but we believe there is a diminished tornado threat because of little instability. A model blend supports most likely peak wind gusts around 30 mph, mainly across the eastern Midlands. There is some concern of stronger wind because of the accelerating storm movement and some possibility of greater instability, but based on the forecast storm track with the greater instability forecast to stay well east of the forecast area we believe this threat is low. Dry ridging is forecast to be in the region Sunday and Sunday night. Low temperatures tonight will be in the mid 50s west to low 60s east. High Sunday should be in the mid 70s to around 80 as skies clear and winds diminish. Lows Sunday night are expected to be in the 50s.
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&& .LONG TERM /MONDAY THROUGH FRIDAY/... The models depict a progressive fall weather pattern during the medium-range period. Ridging is forecast to move off the coast early Monday ahead of an approaching cold front. The front is expected to cross the area Tuesday. The models depict the deepest moisture ahead of the front Monday night into early Tuesday. The dry air mass behind the front should dominate Wednesday and Thursday. Moisture may increase again ahead of sharpening upper troughing and as associated cold front Friday. The GFS and ECMWF MOS support near-normal temperatures during the period. && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
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VFR conditions through tonight. Restrictions expected to develop later this morning and continue through the end of the TAF period in widespread rainfall. Windy conditions this afternoon and evening. Moisture and clouds will increase from the south as Tropical Storm Nestor approaches the northern Gulf Coast tonight, moving across Georgia and South Carolina today as it becomes a post- tropical cyclone. Ceilings expected to lower overnight, but should remain VFR through at least 11-13Z, with a lot of dry air still in place at the surface. Expecting MVFR ceiling restrictions by mid morning at all of the terminals and IFR ceilings and visibility restrictions by 15-17Z at all of the terminals. AGS/DNL terminals will drop first. Potential for moderate to heavy rainfall will increase this afternoon and through the end of the 24-hr TAF period as the deepest moisture and forcing associated with Nestor sets up over the area. Northeasterly winds will also be increasing through the day with gusts up to 20 knots by midday. With 2000 AGL winds forecast to be 35-45 kts and 5000 AGL winds 45-50 kts, approaches and departures will be challenging with strong LLWS. EXTENDED AVIATION OUTLOOK...Showers and associated restrictions with windy conditions through Sunday morning, as a post tropical system moves across southern GA and the eastern Carolinas. A cold front will cross the region Tuesday bringing showers/tstms and associated restrictions Monday night into Tuesday.
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&& .CAE WATCHES/WARNINGS/ADVISORIES...
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GA...Lake Wind Advisory from 2 PM this afternoon to 2 AM EDT Sunday for GAZ040-063>065-077. SC...Lake Wind Advisory from 2 PM this afternoon to 2 AM EDT Sunday for SCZ016-018-020>022-025>031-035>038-041-115-116.
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&& $$

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