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162 FXUS62 KTAE 181321 AFDTAE AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 921 AM EDT Fri Apr 18 2014 ...Heavy Rain and Flooding Concerns Continue into this Evening... ...Strong to Severe Storms Possible mainly SE Big Bend and adjacent Waters... .Near Term [Through Today]...
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Mid morning analysis shows that the leading edge of mid/upper trough continues to dig ESE across Cntrl Gulf region. Closed low over LA. Low Strong jet extends from base of trough Newd to mid- Atlc states while several shortwaves move across SE region. Lead shortwave crossed early this morning leading to blowup of local convection. Another potent shortwave across extreme E TX diving down base of trough increasing divergence across Nrn Gulf of Mex setting us up for next round. At surface...latest MSAS confirmed by marine obs show that upper features have generated MCS low south of Mobile and latest radar pix show it only meandering N/E in last hour. Warm front extends Ewd across Cntrl FL. All this providing excellent isentropic lift...and has strengthened MCS yielding plume of moderate to heavy deep layer moisture moving Newd towards CWA which will increase rainfall amount and intensity. Later today...TX shortwave will amplify SEWD helping to generate closed H5 LOW. Guidance tracks MCS slowly Newd across Wrn FL Panhandle early aftn then just south of Apalachicola during the late aftn. Assocd warm front will likely reach I-10 by mid to late-aftn. This would strengthen Sly flow...intensity moisture plume as it overspreads CWA and further increase amount and intensity of rain as low approaches. This would also place the axis of heaviest rain from Wrn Panhandle thru SE AL and SW GA with the strongest forcing along and just north of the warm front. General 1-2 inches 6 hr rainfall totals (2 to 4 inch total) are expected but higher amounts are likely along and just east of track...i.e. coastal counties from Bay to Wakulla. The only possible curb would be a dry slot currently seen on radar south of Panama City. But latest pix show little N/E movement. With precip water values 50 to 100% above climo, rain rates will occasionally be very high, so we will leave our Flood Watch up and unchanged for our entire forecast area. The global model consensus brings H5 low to FL Panhandle while surface low moves Newd into NE FL by 06z Sat. So wrap around rain will continue especially across NE third of CWA. Clouds and rain will keep max temps well below normal for portions of CWA...near 60 north to mid 70s SE Big Bend. As of 9 AM EDT...rainfall totals were already 2-3 inches across Panhandle and 1-2 inches across the Big Bend...SE AL and SW/S/Cntrl GA. This included Chipley 3.03...Mossy Head 2.80 and Alpine Heights 2.65 in Walton County...Parker (Bay) 2.53...Panama City 2.43... Geneva AL 2.35...DeFuniak Springs 2.29...Tallahassee AP...1.70 and Apalachicola 1.47 inches. Although rain and flooding continues to be the main issue...the threat of strong to isold severe storms is non-zero across mainly Taylor and Dixie counties and adjacent waters. Although mid/upper lapse rates are expected to remain weak...limiting destabilization... Convection Allowing Model (CAM) forecast SBCAPE is in the 500-1000 J/kg range this afternoon in the warm sector with veered low level winds around Cross City and Perry. Given the expected 0-1 km bulk shear magnitude will be around 30 KT in that area, it`s reasonable to be concerned about isolated, low-topped supercells- with damaging wind gusts or perhaps even a brief tornado especially if GFS with its more Nrn track (rather then ECMWF) ends up verifying. Elsewhere we think that thunderstorms will be elevated enough to limit vertical mixing, though the low level winds are strong enough that wind gusts up to 40 MPH are possible. Other concerns to be monitored include possible coastal flooding this afternoon at high tide across coastal Big Bend, high surf advisories and high rip current risk for Walton thru Franklin coasts and gale force winds or gusts for the nearshore panhandle waters and all the offshore waters.
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&& .Hydrology...
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We continue to be on track for a moderate to heavy rainfall event across the forecast area today and tonight. Rainfall totals of 2 to 4 inches are expected to be fairly common, with isolated higher amounts perhaps up to 6 to 8 inches possible. In general, the rivers most likely to flood and have higher impacts will be in the Florida Panhandle and Big Bend where flows are already somewhat elevated. Where the heaviest rain falls, there should also be other flooding on smaller streams and creeks, as well as areas of high water in low-lying areas and fields. A more detailed hydrology discussion is available on our ESF (Hydrologic Outlook) product, which can be found here: http://www.srh.noaa.gov/product.php?site=NWS&product=ESF&issuedby=TAE The most up-to-date river forecast information can always be found on our AHPS page (below). http:/water.weather.gov/ahps2/index.php?wfo=tae.
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&& .Prev Discussion [645 AM EDT]...
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.Short Term [Tonight Through Sunday]... The surface low pressure system will be departing to our east tonight but rain chances will continue through Saturday as wrap around moisture associated with the upper low swings through the Tri-state region. Most of this rain should be light. Deep layer ridging will begin to build in on Sunday with warming temperatures and dry conditions. .Long Term [Sunday Night Through Friday]... By early next week the next weak trough and shortwave moves into Gulf region with weak zonal flow across local area. A surface low well to our NW brings a weak front to the Nrn Gulf before retreating back Nwd on Wed. This will bring a slight chance of rain and isold thunderstorms to the NRN counties Tues and Tues night followed by drying trend. Throughout the entire period, both high and low temps will shows a gradual warming trend. Inland highs Monday in the upper 70s to around 80 will rise to the mid 80s Wed and Thurs. Inland Lows Sun night in the low to mid 50s will rise by Thurs night to the low 60s. .Aviation... [Through 12z Saturday] Rain, occasional thunderstorms, and low cigs (lower MVFR to IFR) are expected at all terminals today. The heaviest rain will end from south to north this evening, followed by IFR cigs and occasional DZ. .Marine... Winds and seas will continue to increase today with gale conditions developing over the western and offshore legs. For the nearshore waters of the Big Bend...advisory conditions will prevail at least through the passage of the low pressure system tonight. The gale conditions for the remainder of the coastal waters will also subside tonight with advisory conditions diminishing by Saturday evening. The strong onshore flow will result in heavy surf and high risk of rip currents along area beaches from Franklin County westward. A coastal flood watch is also in effect along Wakulla County eastward to the mouth of the Suwannee River. .Fire Weather... With such wet conditions today, there will be no fire weather issues (i.e. Red flag conditions) through at least this weekend.
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&& .Preliminary Point Temps/PoPs... Tallahassee 69 53 67 51 76 / 100 60 30 10 0 Panama City 66 50 72 54 77 / 100 30 10 0 0 Dothan 63 48 70 51 76 / 100 50 20 0 0 Albany 63 50 65 50 75 / 100 80 40 10 0 Valdosta 69 55 65 51 75 / 100 80 40 10 0 Cross City 77 59 68 51 77 / 100 60 30 10 0 Apalachicola 70 56 71 53 73 / 100 30 10 0 0 && .TAE Watches/Warnings/Advisories...
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FL...Flood Watch through late tonight for Calhoun-Central Walton- Coastal Bay-Coastal Dixie-Coastal Franklin-Coastal Gulf- Coastal Jefferson-Coastal Taylor-Coastal Wakulla-Gadsden- Holmes-Inland Bay-Inland Dixie-Inland Franklin-Inland Gulf- Inland Jefferson-Inland Taylor-Inland Wakulla-Inland Walton- Jackson-Lafayette-Leon-Liberty-Madison-South Walton- Washington. COASTAL Flood Watch until 8 PM EDT this evening for Coastal Dixie-Coastal Jefferson-Coastal Taylor-Coastal Wakulla. High Rip Current Risk until 8 PM EDT /7 PM CDT/ this evening for Coastal Bay-Coastal Franklin-Coastal Gulf-South Walton. High Surf Advisory until 2 AM EDT /1 AM CDT/ Saturday for Coastal Bay-Coastal Franklin-Coastal Gulf-South Walton. GA...Flood Watch through late tonight for Baker-Ben Hill-Berrien- Brooks-Calhoun-Clay-Colquitt-Cook-Decatur-Dougherty-Early- Grady-Irwin-Lanier-Lee-Lowndes-Miller-Mitchell-Quitman- Randolph-Seminole-Terrell-Thomas-Tift-Turner-Worth. AL...Flood Watch through late tonight for Coffee-Dale-Geneva-Henry- Houston. GM...Small Craft Advisory until 8 PM EDT this evening for Apalachee Bay-Coastal waters From Ochlockonee River to Apalachicola FL out to 20 NM-Coastal waters from Suwannee River to Keaton Beach FL out 20 NM. Gale Warning until 8 PM EDT this evening for 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...BLOCK SHORT TERM...BARRY LONG TERM...BLOCK AVIATION...FOURNIER MARINE...BARRY FIRE WEATHER...FOURNIER HYDROLOGY...CJM

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