Area Forecast Discussion
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932 FXUS62 KTAE 212146 AFDTAE AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 446 PM EST Fri Nov 21 2014 .Near Term [Through Tonight]...
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Very uneventful near term period, with mostly clear skies and a gradual warming trend. Low temps will range from the upper 30s well to the NE to the upper 40s near the coast. .Short Term [Saturday Through Sunday Night]... Nearly zonal upper-level flow locally will begin to amplify on Saturday afternoon in response to a strong shortwave forecast to be passing through Texas. A southern stream PV anomaly will energize convection in the western to central Gulf on Saturday, spreading into the northeast Gulf late Saturday night. The developing warm front will lift into the Tri-State region very early on Sunday morning. Anomalously high PWAT values will combine with a strong southerly low-level jet and boundary parallel upper- layer flow to present a threat for very heavy rainfall. Widespread average rainfall amounts of 2.5"-3.5" will be possible over a relatively short period of time. Due to the progressive nature of the system, any sort of significant flooding is not expected at this time. For further information on the heavy rain threat reference the hydrology section below. Impressive wind shear profiles suggest a non-zero threat for an isolated severe thunderstorm during the overnight hours, though pretty much all thunderstorms should be elevated during this period. On the heels of the aforementioned system, the previously mentioned strong northern stream shortwave will be moving into the Tri-State region. Once again, very impressive shear profiles will overspread the region from west to east through the late morning and afternoon hours on Sunday. The main question will be just how much instability will be present in the wake of the morning rainfall. Early indications from some of our high resolution modeling suggests a quicker progression of the morning rainfall and thus a better chance for destabilization during the day on Sunday, while the global-scale models indicate very little surface destabilization and lingering rain through the day on Sunday. With the event just starting to fall within the range of the higher resolution models, there is quite a bit of uncertainty but given the fact that the global-scale models tend to be a bit slow with isentropic rain development, it is certainly possible that the hires models may be on to something. Should the severe threat pan out, the primary threats would be damaging winds and tornadoes within discrete supercells. The more dynamic shortwave will move out of the region by Sunday evening, stalling a weak front across the region. Continued southern stream support will keep the potential for showers and isolated thunderstorms through the night on Sunday, but the severe threat will have come to an end. .Long Term [Monday Through Friday]... The primary northern stream longwave trough will gradually approach through Tuesday. Increased diffluence between the northern stream and southern stream anomalies will continue to support primarily showers across the eastern half of the region until a stronger cold front clears out all of the rain by Wednesday morning. Arctic high pressure will fill in across the Southeast on Wednesday, capping afternoon highs in the 50s to finish out the week. Overnight lows starting on Wednesday night will fall back into, at least, the lower 30s.
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&& .Aviation...
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[Through 18Z Saturday] VFR conditions are expected to prevail through the period, with some increasing cloudiness during the afternoon hours. Also, winds nay become a bit breezy out of the E and NE (greater than 10 kts) from early in the afternoon onwards.
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&& .Marine...
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Advisory level winds and seas should be expected through Sunday associated with a complex frontal system. A temporary dip below headline levels is expected on Monday before another strong cold front re-introduces headline conditions on Tuesday, possibly through the end of the week.
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&& .Fire Weather...
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With increasing low level moisture and rain chances, no Red Flag concerns are expected through the weekend. In fact, Wet Flags are expected on Sunday.
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&& .Hydrology...
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Storm total rainfall amounts Saturday through Tuesday will be on the order of 2 to 4 inches, with most of the rainfall coming over a 12 hour period late Saturday night through Sunday morning. Low river levels will likely prevent any river flooding even with these high totals. However, there is a concern for some localized flooding in the more urbanized locations that receive the higher totals over a short period of time. Any decisions about a Flash Flood watch will likely come overnight tonight, or tomorrow afternoon when more guidance becomes available.
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&& .Preliminary Point Temps/PoPs...
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Tallahassee 45 68 60 75 64 / 0 20 100 70 50 Panama City 49 67 63 75 66 / 0 30 100 80 50 Dothan 40 65 56 74 62 / 0 10 100 80 40 Albany 39 65 56 74 63 / 0 10 100 80 50 Valdosta 43 68 58 76 64 / 0 20 100 80 50 Cross City 49 72 63 77 64 / 0 20 100 60 40 Apalachicola 51 67 66 74 67 / 0 30 100 60 50
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&& .TAE Watches/Warnings/Advisories... FL...None. GA...None. AL...None. GM...Small Craft Advisory until 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. && $$ NEAR TERM...GOULD SHORT TERM...HARRIGAN LONG TERM...HARRIGAN AVIATION...GOULD MARINE...HARRIGAN FIRE WEATHER...GOULD HYDROLOGY...HARRIGAN

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