730 FXUS62 KTAE 130307 AFDTAE AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 1107 PM EDT Fri Jul 12 2013 .NEAR TERM [Through Tonight]... Other than some adjustments to PoPs with some fairly strong storms lingering well after sunset, current fcst is essentially on track and only additional minor tweaks to the current package were made. && .SHORT TERM [Saturday Night Through Sunday Night]... This promises to be a complex forecast due to a very atypical pattern we have setting up over the CONUS. An upper level low in the vicinity of the OH/WV border is dropping southward toward eastern KY this afternoon, but will begin to retrograde westward tonight and be positioned over eastern KS by Sunday. After that, the system will drop southward into the Southern Plains. Surface analysis shows a northeast to southwest oriented trough bisecting our forecast area. The tricky part of the forecast involves the development of a closed circulation on this trough and where it moves once formed. There is now a general model consensus that low pressure will develop over the northeast Gulf of Mexico and if it does, it will be pulled closer to the coast as the upper system gains longitude and pulls it northward. It appears at this time that a closed circulation can be deduced from satellite imagery and buoy data just southeast of the mouth of the Mississippi River. We therefore chose to go with the more westward cyclogenesis depicted in the GFS. This model then draws the low northwestward toward the Mississippi coast on Sunday. The take away here is that there is a lot of uncertainty in the forecast and that winds could change considerably over what is issued today. Regardless of where the low develops, it does appear more certain that a high PoP forecast remains in order. Drier air aloft will initially keep PoPs lower across our western zones, but likely PoPs are expected for most areas with categorical for the eastern FL Big Bend counties on Saturday. && .LONG TERM [Monday through Friday]... By the start of this period, the upper low will have retrograded all the way to the Southern Plains with a large upper high centered over Ohio ridging southward to the Northeast Gulf of Mexico. The surface ridge will be displaced a bit to the east of the upper feature, but will still ridge into our area. The deep layer ridging would normally suppress convection below typical summertime levels. However, a series of easterly waves will work their way across the FL Peninsula during this time and keep PoPs closer to normal. It should be noted that the NAM brings a tropical cyclone to the east coast of FL by Monday evening and is being discounted in favor of an open wave. Temps will be close to normal overnight and a couple of degrees below normal during the afternoons. && .AVIATION ... [Through 00 UTC Sunday] The Hi-Res models were not very aggressive at all with flying restrictions overnight tonight, but this could change with early evening rainfall after sunset. For this package, just went with MVFR at DHN, ABY, and VLD, but TLH may need to be amended later tonight with 0.29" of rain falling after sunset. && .MARINE... This forecast will be subject to some substantial modifications over the next 24 hours as we await the development of low pressure over the northeast or north central Gulf of Mexico. At this time, we anticipate a low developing southwest of the waters tonight and lifting northwestward toward Mississippi on Sunday. Other models have the low developing further east over the forecast waters. If this happens, the forecast will need to be updated. As it stands now, we are calling for exercise caution conditions to develop over the western legs on Saturday and continuing through the weekend. During the upcoming work week, high pressure will build north of the waters setting up an easterly flow regime with surges of wind to near cautionary levels during the overnight and morning hours. && .FIRE WEATHER... Red Flag conditions are not expected for some time. && .HYDROLOGY... All river points that have been in flood continue to recede, albeit slowly on the lower Choctawhatchee, where Caryville and Bruce will remain at flood stage for some time. Routed flows from the Withlacoochee and Alapaha Rivers are progressing downstream and are now beginning to initiate rises in the lower portions of these rivers and into the Middle Suwannee. There is considerable capacity in the Suwannee Basin, so barring significant rainfall, flooding is not anticipated along the Middle Suwannee, though flows may approach action stage by the middle of next week at Ellaville and Dowling Park. It is helpful that routed flows from the Upper Suwannee remain relatively low, as the bulk of the expected rise on the Middle Suwannee is occurring from the Withlacoochee and Alapaha Rivers. The rainfall over this weekend is expected to average aerially around 2 to 3 inches, with isolated heavier totals possible. This certainly does not look to be like the significant flooding rainfall we saw last week, and as a result, widespread flooding is not anticipated. However, given the wet soil conditions across much of North Florida and Southern Georgia, a couple of inches of rain in a short amount of time could easily generate localized flooding, especially in an urban environment. Expected rainfall could keep rivers currently in flood at those levels well into next week (like the Choctawhatchee) and could result in basins like the Ochlockonee or Chipola nearing flood stage depending on the location of the heaviest rains. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 72 84 72 89 72 / 60 70 40 60 40 Panama City 73 85 74 86 75 / 50 60 30 50 40 Dothan 72 84 71 85 72 / 60 60 30 50 30 Albany 73 84 72 89 72 / 40 70 40 60 30 Valdosta 72 88 72 91 72 / 70 80 40 60 30 Cross City 71 88 72 89 71 / 60 80 40 60 30 Apalachicola 72 83 73 88 75 / 50 70 40 50 50 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AL...None. GM...None. && $$ NEAR TERM...Gould SHORT TERM...Wool LONG TERM...Wool AVIATION...Gould MARINE...Gould/Wool FIRE WEATHER...Harrigan HYDROLOGY...Godsey