Tuesday Morning Forecast

Forecast issued by Justin Gibbs on 09/19/06 at 12:53:01 am CDT

Mobile, Alabama 5 Day Forecast
Today	Wednesday	Thursday	Friday	Saturday
84°F	83°F	85°F	86°F	84°F
	58°F	60°F	69°F	70°F
SW 5-10 mph	Lgt NW	S 5-10 mph	SE 5-10 mph	SW 5-10 mph
60%	0%	0%	30%	30%

Mobile, Alabama 5 Day Detailed Forecast

Today... Variable cloudiness with showers and thunderstorms likely in the morning. Then clearing and cooler. High 84. Winds southwest 5-10 mph, shifting to the northwest at 5-10 mph by afternoon. Chance of rain is 60 percent. Tonight... Mostly clear. Low 58. Winds northwest 5-10 mph. Wednesday... Sunny. High 83. Winds Light northwest winds. Wednesday Night... Clear. Low 60. Winds south 5-10 mph. Thursday... Mostly sunny. High 85. Winds south 5-10 mph. Thursday Night... Mostly clear. Low 69. Winds south 5-10 mph. Friday... Partly cloudy with scattered showers and thunderstorms. High 86. Winds southeast 5-10 mph. Chance of rain is 30 percent. Friday Night... Partly cloudy with scattered showers and thunderstorms. Low 70. Winds south 5-10 mph. Chance of rain is 30 percent. Saturday... Partly cloudy with scattered showers and thunderstorms. High 84. Winds southwest 5-10 mph. Chance of rain is 30 percent.

Technical Discussion

Synopsis: 04z Surface Analysis lines up cold front along a line from KBTR to KTCL to KGAD. Upper air charts indicate a nearly vertically stacked closed low centered over NERN MN which is responsible for the sfc cyclone. 500/700mb RAOB data indicate a s/wv across western LA and SRN AR. KLIX/KTLH soundings show a very saturated air mass with minimal positive buoy area with SBCAPEs aoa 1500 j/kg. Upper air analysis shows slightly cooler air aloft closer to the main s/wv axis which combined with sfc convergence invof the frontal boundary is believed to be responsible for the latest flare up of +TSRA currently located acrdoss SRN MS/NRN LA. Forecast Discussion (Tuesday through Saturday): Short Term... Main forecast challenge is handing of 1st period pops. Guidance is in firm agreement of a 12-14z FROPA. WV/Soundings indicate bone dry air behind the main frontal boundary so do not expect anything in the form of postfrontal precip. Given the saturated air above us and the nature of the development to our west there is a 70-80% chance of precip across the Mobile metro area with the system however linear extrapolation of the line brings it through around 4:30 a.m. So it is simply a matter of making a determination if the system will clear before or after 6 a.m. So will assume it may slow some and go with 60% morning pop wording. Will also stick with going high which is a touch below MOS but will allow for full FROPA+loss of about 3 hours of insolation+lower heighs associated with deep layer s/wv. Severe weather currently appears rather unlikely as a look at forecast/observed soundings show a very thin positive area on the sounding which will largely limit updraft acceleration (which is likely why storms over SRN MS are having a hard time producing dBZ values above 50 at ~20kft.) Additional daytime heating post 12z may allow for some stronger storms, but this line should be moving east of the area before much in the way of substantial heating is expected. Tuesday evening puts us in a very dry postfrontal airmass with relatively light northwest winds. Weak ridging builds in at the sfc and aloft by tomorrow evening. Fcst soundings continue to show very low PWAT values with Tds down in the mid to upper 50s across the board as well. Going forecast sems to have a good handle on the next few periods as ridge builds at the sfc before being pushed eastward by our next feature expected to arrive Friday. Long Term... NAM/GFS/ECMWF both develop another strong upper level storm system which forms a sfc cyclone that pushes NE'wd across the central CONUS. As this low builds, our sfc winds will shift to the south and southeast. Will stick with going forecasts handling of doing this on Thursday. Thursday evening projects a rather substantial airmass modification as again our very dry airmass is loaded up with moisture as the dominant low/mid/upper level flow becomes southerly ahead of the appraoching trof. Frontal passage is a bit tricky as GFS/UKMET both appear to develop another southerly sfc low which slows things down rather substantially. GFS even appears to hint at the idea the boundary will nearly wash out altogether. This doesnt appear particuarly likely at the time given the strength of the upper level pattern so will not make any changes to the going package's handling of PoPs as a more conservative approach appears prudent with this system. ECMWF goes ahead with frontal passage during the early morning Saturday and that is the preferred solution for this package. Will introduce 30 POPs to the daypart Saturday.

Hazardous Weather

Hazardous Weather Outlook (Tuesday through Saturday): A cold front will approach the area overnight and will result in a continued chance for showers and thunderstorms until it passes Tuesday morning. Because the atmosphere is so moist, thunderstorms that do occur will be capable of very heavy rainfall which could lead to brief flooding of streets in urban areas. Widespread flooding problems are not expected, however. Although strong thunderstorms may bring heavy rainfall and dangerous lightning, severe thunderstorms are not expected.

Astronomical and Climatological Data
Moon Phase Crescent Waning Sunrise 6:38 AM Sunset 6:52 PM	09/19/06 Normal High Record High Normal Low Record Low Temperature 86°F 97°F (1925) 67°F 48°F (1981) September Normal Wettest Driest Precipitation 6.01 in. 24.12 in. (1998) 0.47 in. (1923)

09/19 in Mobile Area Weather History

In 1998 an early afternoon storm produced a waterspout that moved inland near Gulf Shores in Baldwin County, AL. The tornado quickly weakened and no damage was found. (Data compiled from NWS Mobile, NWS Birmingham, newspaper articles, USA Archives and HurricaneCity.com)