Area Forecast Discussion
Issued by NWS
Issued by NWS
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091 FXUS62 KTAE 161723 AFDTAE Area Forecast Discussion National Weather Service Tallahassee FL 123 PM EDT Sun Jun 16 2024 ...New AVIATION... .SYNOPSIS... Issued at 403 AM EDT Sun Jun 16 2024 A surge of moisture from the south today will support a significant one-day increase in shower and thunderstorm coverage. Strong high pressure will develop tonight over the U.S. Mid- Atlantic region, pushing drier air and unseasonably strong easterly breezes across the region from Monday through at least Wednesday. Moisture will increase from Thursday through Saturday as a fast-moving easterly wave moves off the Atlantic and across the tri- state area. && .NEAR TERM... (Today and tonight) Issued at 403 AM EDT Sun Jun 16 2024 Early this morning, a very moist air mass was located just south of the forecast area, characterized by Precipitable Water (PW) values well in excess of 2 inches. In fact, the TBW sounding from Saturday evening observed a PW of 2.22 inches, which is near the max moving average for mid-June in the SPC sounding climatology for TBW. This moist air is spreading northwest and will overspread areas along and southwest of a Eufaula to Valdosta line later today. This will really prime the air mass for a large increase in shower and thunderstorm coverage today. Indeed, convection has increased rapidly since midnight about 70-80 miles south of Apalachicola over the warm 85-degree Gulf waters. This serves as another sign of the expected increase in showers and thunderstorms further north and inland today. High temperatures will trend down a few degrees today, due to increased clouds and rain-cooled air. Late tonight, low-level flow will turn from southeasterly to more easterly, bringing drier air. Showers and storms will wane late this evening and overnight. && .SHORT TERM... (Monday through Wednesday) Issued at 403 AM EDT Sun Jun 16 2024 A strong 500 mb high over the Carolinas will expand toward the U.S. Mid-Atlantic region and strengthen impressively during the first half of the week ahead. In response, the southern periphery of strong surface high pressure will bridge down the Southeast Atlantic coast. This will happen concurrent with development of a tropical low or perhaps a tropical cyclone over the southwest Gulf (see NHC Tropical Weather Outlook). An unseasonably strong pressure gradient will develop between these two features, and a prolonged period of strong easterly flow will get underway and crank up on Monday and Monday night. A dry air mass emanating from the strong surface high to our northeast will funnel into the forecast area from the northeast and east. PW values will be in the process of dropping below 1.5 inches on Monday, then bottom out in the 1-1.5 inch range on Tuesday and Wednesday. Have reluctantly carried slight chance PoPs forward in the forecast over our FL counties from Monday through Wednesday, but PW values well below 1.5 inches suggest a greater potential for convective shutdown on those days. In the unseasonably breezy environment, mesoscale speed surges and speed convergence could generate some transient low-topped convection, which is the justification for holding onto low PoPs for now. && .LONG TERM... (Wednesday night through Saturday) Issued at 403 AM EDT Sun Jun 16 2024 The southern base of the upper trough out near Bermuda today will get detached from the mid-latitude westerlies, then become orphaned and transition into an easterly wave as strong high pressure builds in to its north over the U.S. Mid-Atlantic region. This easterly wave or inverted trough should pass westward past the Bahamas on Wed night, then across the FL Peninsula and south Georgia on Thursday, then across the FL Panhandle and Lower Alabama around Thursday night. As low-mid level flow quickly flips out of the southeast behind this trough axis, a moister air mass will stream in and bring a return of convection from Thursday through Saturday. A small but growing number of guidance members do form a closed low around midweek somewhere within the easterly wave axis. Such development could happen just about anywhere along or east of the Florida/Georgia coast. The latest NHC Tropical Weather Outlook from 2 AM EDT on Sunday reflects this possibility with a low chance (30 percent) of tropical cyclone formation around midweek. If this occurs, it would be a fast-moving system coming off the Atlantic, moving westward or west-northwestward. && .AVIATION... (18Z TAFS) Issued at 122 PM EDT Sun Jun 16 2024 Scattered showers and thunderstorms are developing across our Florida terminals. This will continue through the evening hours. Valdosta and Albany may see shower/thunderstorms later this evening due to the Atlantic seabreeze pushing in from the east. With these storms, downbursts will be possible, leading to gusty winds. Also, frequent lightning will be a concern. Convective activity should diminish after sunset. Winds will be light to calm overnight before becoming easterly during the day tomorrow. Following this TAF period, easterly winds may be gusting up to 20 knots for the afternoon. && .MARINE... Issued at 403 AM EDT Sun Jun 16 2024 It is going to be an unseasonably rough week on the waters, as easterlies start to pick up tonight. The roughest conditions will come from Tuesday through Thursday. This will also make for dangerous rip currents along our beaches this week. A prolonged period of fresh to strong easterly breezes will develop on Monday and then continue through at least Thursday. This will occur as pressure gradients tighten between strong high pressure off the U.S. Mid-Atlantic coast and deepening low pressure over the southwest Gulf. Small craft advisory conditions are expected for much of the week ahead, marked by nocturnal surges and afternoon lulls that are common in easterly flow. && .FIRE WEATHER... Issued at 403 AM EDT Sun Jun 16 2024 The air mass will moisten substantially today, bringing an increase in shower and thunderstorm coverage through this evening. Then unseasonably strong easterly flow will develop on Monday and continue through about next Friday. This will come with a dry air mass from Monday through Wednesday, then some moistening on Thursday and Friday. Given the strong transport winds starting Monday, look for high dispersion values for much of the week ahead. && .HYDROLOGY... Issued at 403 AM EDT Sun Jun 16 2024 Shower and thunderstorm coverage will increase today, posing the concern for intense rainfall rates within the core of heavier thunderstorms which could lead to short-lived runoff issues. However, no widespread or significant flooding is expected. Rainfall, if any, from Monday through Wednesday will be hydrologically insignificant. Shower and thunderstorm coverage will increase from Thursday through Saturday, once again posing the risk of short-lived runoff issues stemming from intense rainfall rates beneath the core of heavier thunderstorms. Riverine flooding is not expected. && .SPOTTER INFORMATION STATEMENT... Spotter activation is not requested. However, spotters are always encouraged to safely report significant weather conditions when they occur by calling the office or tweeting us @NWSTallahassee. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 74 94 74 94 / 50 30 0 20 Panama City 76 92 76 93 / 20 30 20 20 Dothan 73 93 73 92 / 30 20 20 10 Albany 73 94 72 92 / 40 20 10 10 Valdosta 72 94 71 93 / 20 20 0 10 Cross City 71 94 71 93 / 40 30 0 30 Apalachicola 79 88 78 89 / 30 20 20 20 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk through late Thursday night for FLZ108-112- 114-115. GA...None. AL...None. GM...None. && $$ NEAR TERM...Haner SHORT TERM...Haner LONG TERM....Haner AVIATION...Montgomery MARINE...Haner FIRE WEATHER...Haner HYDROLOGY...Haner