Tuesday Morning Forecast

Forecast issued by Justin Gibbs on 11/28/06 at 1:39:49 am CST

Mobile, Alabama 5 Day Forecast
Today	Wednesday	Thursday	Friday	Saturday
76°F	75°F	78°F	62°F	61°F
	59°F	63°F	60°F	40°F
SE 5-10 mph	SE 10-15 mph	SE 10-20 mph	NW 10-15 mph	W 4-8 mph
0%	30%	50%	0%	0%

Mobile, Alabama 5 Day Detailed Forecast

Today... Partly cloudy. High 76. Winds southeast 5-10 mph. Tonight... Partly cloudy with fog forming in the evening hours. Dense Fog possible in some areas. Low 59. Winds southeast 7-14 mph. Wednesday... Partly cloudy with scattered showers. High 75. Winds southeast 10-15 mph. Chance of rain is 30 percent. Wednesday Night... Partly cloudy with scattered showers and thunderstorms. Low 63. Winds southeast 10-15 mph. Chance of rain is 40 percent. Thursday... Mostly cloudy with scattered showers and thunderstorms. High 78. Winds southeast 10-20 mph. Chance of rain is 50 percent. Thursday Night... Cloudy with showers and thunderstorms likely. Low 60. Winds south 10-20 mph. Chance of rain is 60 percent. Friday... Variable clouds with partial clearing in the afternoon. Isolated showers and storms in the morning. High 62. Winds northwest 10-15 mph. Friday Night... Partly cloudy. Low 40. Wind chill values as low as 34 degrees are possible. Winds northwest 5-10 mph. Saturday... Partly cloudy. High 61. Winds west 4-8 mph.

Technical Discussion

Synopsis: Rather active pattern exists over the CONUS this morning with the main theme being ridge east..trough west. Mean deep layer ridge axis looks to be continuing to shift to the east; currently looking to be over GA/NC/WRN VA with the sfc ridge axis in the vcnty of a New Orleans to Atlanta line. However, this ridge is beginning to loosen its grip on our weather as the winds begin to pick up and the main ridge shifts ewd (currently centered over ERN Canada with the trof axis running along the eastern seaboard. Further upstream a once closed upper level low has again reopened as forecast and continues to dig east/southeastward. 0z Data puts the 500mb trof axis along a Sacremento, CA/Portland, OR line as it shifts eastward. This rather robust upper level low has led to surface cyclogenesis which remains underway on the lee side of the rockies. 0z KLIX sounding continues to reveal a very dry airmass with PWATs around 0.67 with strong indications of subsidence in the form of an inversion around 800mb. Forecast Discussion (Tuesday through Saturday): Short Term... Pressure gradient will tighten as the afforementioned low pushes eastward through the first few periods. Going wind forecast looks to be in good shape with SE winds at 5-10mph. NAM/GFS projections show little change in the overall airmass/column thickness for the first period from what we saw today...so feel comfortable with the MOS consensus of 76 which is 1 degree warmer than what we saw today. As the winds move to the southwest, guidance is in solid agreement with a slow modification of our airmass, especially in the lower levels. This slow increase in moisture provides confidence in continuing the going Partly Cloudy forecast in the first period. We will likely see a cloud or two more into the overnight hours as the slow modification continues. 700/850mb/sfc NAM/GFS windfields also continue to support the eeking upward of the wind speeds to the 7-14mph range as the upper level and surface low continue to approach from the west. Main question regarding 2nd period lows revolves around the amount of moisture advection we will see during the day today. Guidance looks to bring dewpoints of 58/60 in by late evening. That lines up well with what we are seeing tonight (looking downstream) so will lean on the more mixed side of things and go with 59 for the second period low. Will also include fog, as an event slightly more substantial than tonights looks to be in the cards as the dewpoint depression looks to drop to 0 at several regional stations by 3-4z. Agreement amongst guidance and MOS and low visibility signals amongst the MOS suite, will go ahead and mention dense fog in some areas and patchy fog metro area wide. Later shifts will likely need to reevaluate this and make mention of what may become a more significant fog event in the overnight hours Tuesday. Wednesday it appears we will begin to be within flirting range of the warmfront ahead of the surface low. Nevertheless, a slight amount of overrunning looks to be possible during the day Wednesday. Also will bump windfields up a half category to 10-15mph to come into better agreement with the latest GFS guidance which looks good in response to the deepening trof through the column and the subsequent behavior of the sfc storm system. With the tightening windfield and associated overrunning will go with a slight step in the wetter direction with a 30% pop in the afternoon and maintain the going 40% pop in the overnight hours. Will also handle the thunder/no thunder similarly adding the chance of a rumble in the post 0z hours once a bit of elevated instability builds in closer to the warmfrontal boundary. Will remain on the Mostly Cloudy boat through the passage of the storm system due to the substantial column moisture expected to be in place invof the low. Overall, prefer the slightly slower and HPC endorsed GFS on timing, this brings the main frontal boundary through in the 10z time frame. Will slow this down a few hours to allow for slowdown during a very complex evolution of this storm system. Will go with a mostly cloudy and breezy solution for the Wednesday/Wednesday night period as the warm front passes early in the day and we remain in the warm sector. Mid-level moisture will be somewhat lacking subsequently mid level lapse rates follow suit with nothing greater than 5 c/km indicated in any going guidance. Forecast soundings and MUCAPE plan view fields reveal about 500-1000 j/kg CAPE at peak instability from surface based lifted parcels (elevated instability earlier in the event looks to be in the sub 500 j/kg range.) Best dyanmical support may be just behind the event as during frontal passage we look to be in the 20-40kt range in the 0-6km range. Additionally the best low level jet (>50kts) looks to build in over the lower Ohio Valley as opposed to this region. Backed sfc winds in the warm sector to yield 0-1km SRH values in the 150-200 m2/s2 levels which would help support rotating updrafts in the event of convection in this area. That being said there are a lot of questions regarding how all of this will come together but it appears we run a relatively conditional threat for severe weather, with it being too early to get detailed as to the main threats. The rain and thunderstorm threats though are pretty cut and dried, so will bump to likely pops for the Wednesday night period and hold the going 50% for the Thursday day period, mainly becuase of questions regarding timing. Will carry the going blustery wind forecast into into the Thursday evening period as well. Long Term... Friday the front looks to push through by noon at the very latest, will introduce a 20% pop to ease the possibility of a slowed FROPA into the forecast. Will include morning wording on this however and paint a cooler and breezy forecast picture. Like the going 'variable cloudiness' as the best 4th and 10 scenario for the time being, but additionally believe with the ribbons of moisture behind the front that likely will be the best depiction of sensible wx for the day. Friday evening looks to be a cool and mostly clear night. MOS consensus is around 42 but will tweak that a touch downward as it appears the cloud cover is a bit too high considering the column moisture that will be present (not to say there won't be any clouds--but there probably won't be quite as many as the GFS is currently forecasting) so will go with a 40 for Friday evening. Will paint a partly cloudy and 61 degree day for Saturday as a ridge builds to our west.

Hazardous Weather

Hazardous Weather Outlook (Tuesday through Saturday): Fog will become possible in the evening and overnight hours Tuesday across the Mobile area. Current indications are the fog may be rather widespread and likely will be dense in some areas. Motorists with travel plans for Tuesday night should be prepared for the possibilty of rapidly reduced visibilities in areas of heavy fog. Areas such as the Mobile Bayway and Causeway and areas over and near bodies of water will be most susceptible to dense fog. By midweek organized showers and thunderstorms are expected, there is a slight chance a few of these storms may be severe, mainly on Thursday evening and early Friday morning. It is too early to provide details on the type of severe weather that may occur or exact timing of this system. Residents of the Mobile area should monitor updated forecasts throughout the week as the event nears and more details become available.

Astronomical and Climatological Data
Moon Phase First Sunrise 6:29 AM Sunset 4:51 PM	11/28/06 Normal High Record High Normal Low Record Low Temperature 67°F 80°F (2005) 45°F 25°F (1938) November Normal Wettest Driest Precipitation 5.41 in. 13.65 in. (1948) 0.06 in. (1924)