Area Forecast Discussion
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139 FXUS62 KTAE 222116 AFDTAE AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 416 PM EST Sat Nov 22 2014 .Near Term [Through Tonight]...
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A strong northern stream +PV anomaly is merging in with a southern stream anomaly over the northwest Gulf coast this afternoon. In the low-levels, flow is veering as high pressure is forced eastward by the advancing low pressure system. This morning, the veering flow forced a warm and very moist airmass across the eastern Gulf and Florida Peninsula, over a cooler airmass in place locally. This resulted in light to moderate isentropic rain across the entire Tri-State region that continues at this hour. Expect waves of light to moderate rain to continue for the remainder of the afternoon. Further south in the eastern Gulf, a surface trough is forming where the nose of the southern stream anomaly is spreading away from the northern stream flow, resulting in enhanced diffluence aloft. Since midday, convection has steadily increased in this region. Through the night, convection in the Gulf is expected to become more robust and move north in the increasingly southerly flow regime. This will force the trough/warm front north to the northeast Gulf coast very early on Sunday morning. Thus, through the night expect showers and embedded thunderstorms to continue to move north across the region with rainfall becoming much heavier. At this time, severe weather is not expected overnight as storms are unlikely to be rooted at the surface. .Short Term [Sunday Through Monday Night]... By dawn on Sunday, the aforementioned area of heavy rain and isolated thunderstorms will be steadily moving north through the region. At the same time, the aforementioned northern stream anomaly will be quickly approaching. The core of this system will likely pass just northwest of us, through central MS & AL, into TN. However, due to the strength and size of this system 40-50kts of deep layer shear will still be able to reach the Tri- State region, coincident with with a recovering boundary layer yielding around 1000 J/kg of SBCAPE and a strong LLJ. While there may be some discrete convection ahead of the main squall line, the greatest threat for more widespread severe coverage will occur along along the expected squall line forecast to enter our Panhandle and Alabama counties around mid afternoon. Both damaging thunderstorm winds and tornadoes should be expected with any discrete development and along the squall. The severe threat will gradually diminish through the late afternoon and evening as the squall progresses east; with a much lower threat for severe weather east of a line from Tallahassee to Albany as both wind shear and instability wane. A weak front will bisect the region through the day on Monday as deep layer southerly flow impedes the forward progress of the system. Showers and isolated thunderstorms should be expected Sunday night through Monday, especially along and east of a line from Panama City through Albany. However, these storms are not expected to become severe. .Long Term [Tuesday Through Saturday]... The amplifying northern stream longwave trough will finally push the surface front and any moisture out of the region by Wednesday evening. In its wake, dry conditions with highs in the lower to middle 60s and lows in the middle to upper 30s are anticipated through the remainder of the week.
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&& .Aviation...
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[Through 18Z Sunday] MVFR to IFR conditions will spread north from the coast through the remainder of the afternoon, reaching KABY and KDHN by sunset. Cigs will remain low through Sunday morning. Cigs may rise by late morning or early afternoon. However, thunderstorms will be likely thereafter.
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&& .Marine...
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A very strong low pressure system will yield solid advisory conditions through Sunday night. On Sunday, frequent gusts to Gale force are expected. Thus have kept the Gale warning in place. Strong to severe storms will also be possible across the northeast Gulf late tonight, but more likely on Sunday. While advisory conditions will come to an end on Monday, expect cautionary conditions to continue until another front increases winds again Tuesday into Wednesday.
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&& .Fire Weather...
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Wet weather will minimize any fire weather risk through Sunday. By Monday, a drier airmass will move into the region but humidity values are forecast to remain above critical levels.
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&& .Hydrology...
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Periods of heavy rain will move through the region tonight through Sunday night, resulting in total rainfall amounts of 2-3 inches with local amounts up to 4 inches possible. This will cause rises on smaller creeks and rivers next week. Since rivers are all very low at this time, the only river that we are expecting to get to minor flood stage is the Kinchafoonee River at Dawson, possibly by mid week.
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&& .Preliminary Point Temps/PoPs...
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Tallahassee 63 76 64 79 49 / 100 100 50 40 20 Panama City 63 74 64 75 51 / 100 100 50 30 10 Dothan 59 74 59 73 44 / 100 100 40 20 10 Albany 60 74 61 75 46 / 100 100 50 30 10 Valdosta 60 77 67 78 50 / 100 80 70 50 20 Cross City 63 78 67 78 53 / 100 60 60 50 20 Apalachicola 66 74 66 76 53 / 100 100 50 50 20
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&& .TAE Watches/Warnings/Advisories...
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FL...High Rip Current Risk through late Sunday night for Coastal Bay- Coastal Franklin-Coastal Gulf-South Walton. High Surf Advisory from 9 AM Sunday to Midnight CST Sunday Night for Coastal Bay-South Walton. GA...None. AL...None. GM...Small Craft Advisory from 1 AM to 7 PM EST Sunday for Apalachee Bay-Coastal waters from Suwannee River to Keaton Beach FL out 20 NM. Small Craft Advisory until 1 AM EST Sunday for Coastal waters From Ochlockonee River to Apalachicola FL out to 20 NM- Coastal waters from Apalachicola to Destin FL out 20 NM- Waters from Suwannee River to Apalachicola FL from 20 to 60 NM-Waters from Apalachicola to Destin FL from 20 to 60 NM. Small Craft Advisory from 7 PM Sunday to 7 AM EST Monday for Coastal waters From Ochlockonee River to Apalachicola FL out to 20 NM-Coastal waters from Apalachicola to Destin FL out 20 NM-Waters from Suwannee River to Apalachicola FL from 20 to 60 NM-Waters from Apalachicola to Destin FL from 20 to 60 NM. Gale Warning from 1 AM to 7 PM EST Sunday for Coastal waters From Ochlockonee River to Apalachicola FL out to 20 NM- Coastal waters from Apalachicola to Destin FL out 20 NM- Waters from Suwannee River to Apalachicola FL from 20 to 60 NM-Waters from Apalachicola to Destin FL from 20 to 60 NM.
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&& $$ NEAR TERM...HARRIGAN SHORT TERM...HARRIGAN LONG TERM...HARRIGAN AVIATION...CAMP MARINE...HARRIGAN FIRE WEATHER...CAMP HYDROLOGY...HOLLINGSWORTH

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