Tuesday Morning Forecast

Forecast issued by Randy Bowers on 11/14/06 at 3:05:12 am CST

Mobile, Alabama 5 Day Forecast
Today	Wednesday	Thursday	Friday	Saturday
71°F	74°F	62°F	68°F	73°F
	63°F	48°F	39°F	40°F
S 10-20 mph	SW 10-20 mph	NW 10-20 mph	W 2-4 mph	W 2-4 mph
10%	90%	0%	0%	0%

Mobile, Alabama 5 Day Detailed Forecast

Today... Areas of fog this morning giving way to mostly sunny skies. Becoming partly cloudy during the afternoon. High 71. Light south wind increasing to 10 to 20 mph late. Tonight... Mostly cloudy with showers and thunderstorms becoming likely. Low 63. Winds south at 15 to 25 mph with gusts around 30 mph. Chance of rain is 60 percent. Wednesday... Mostly cloudy with thunderstorms. Some storms may be severe with damaging winds. High 74. Winds southwest 15 to 25 mph with gusts to around 30 mph. Chance of rain is 90 percent. Wednesday Night... Mostly cloudy with a slight chance of showers. Low 48. Winds northwest 10 to 20 mph. Chance of rain is 20 percent. Thursday... Mostly cloudy. High 62. Winds northwest 10 to 20 mph. Thursday Night... Mostly clear. Low 39. Winds west 4 to 8 mph. Friday... Mostly sunny. High 68. Winds west 2 to 4 mph. Friday Night... Mostly clear. Low 40. Winds west 2 to 4 mph. Saturday... Mostly sunny. High 73. Winds west 2 to 4 mph.

Technical Discussion

Main focus for this forecast will be potent mid/upper trough that is to impact the area starting tonight. Several concerns with this system from strong gradient winds, to potential for severe tstms and heavy rainfall. Sfc ridge axis located over the area early this morning with calm winds at KMOB last hr. Td/T depressions narrowing and a few areas of fog has formed per area ASOS network. Fog that does form later this morning should mix out quickly with diurnal heating. Meanwhile, Srly flow should increase dramatically throughout the day in response to lee sfc cyclogenesis evolving as a result of digging/amplifying mid/upper trough. Per previous AFDs and HPC PMDHMD, NAM has trended deeper/further south and slightly slower over the past few runs. This results in more intense sfc cyclone over the Mid-South with a slightly further south track than previously expected. Strength and position of surface low raises concern for strong gradient winds. In fact, 00z guidance consensus is for slightly stronger winds than going forecast has. Have raised pre-frontal sfc winds in public forecast in Tue night-Wed timeframe. Post-frontal winds were also on the low side and chose to increase as well. LLJ/WAA expected to strengthen dramatically late Tue/Tue night w/ potential for WAA SHRA/TSRA as soon as Tuesday evening. Have thus reintroduced PoP for Tue night period and have chosen to go likely. Toward daybreak Wed, position of 850 mb LLJ and warm front/best low-level moisture favors increased potential for deep convection. GFS and NAM forecast soundings both indicating rather substantial positive area w/ column CAPE AOA 1800 J/KG. Much of this is located in the lower portion of the column where best lapse rates reside. Significant 0-3 km CAPE and strong shear yielding EHI values approaching 3. NAM is overall weak with mid-level lapse rates, while GFS is slightly steeper but shows a rather substantial inversion between 500 mb and 700 mb. Feel that given this, best chance for deep convection would be in the form of a squall line during the afternoon where forcing/convergence along sfc boundary should be sufficient. Convection along the warm front or discrete cells in the warm sector likely to remain rather shallow. Despite this, low-level speed shear will be significant. 0-1 km shear AOA 35 kts or greater will be present. Given this, damaging winds would be a concern in even shallow convection. Undoubtedly, damaging winds will be the primary severe wx concern given intense wind fields. Directional shear in the lowest 3 km not overly impressive and substantial tornado threat is therefore not expected. Still, sufficient directional shear combined with intense speed shear will be enough for the threat of isolated tornadoes, particularly in discrete cells or embedded supercells within the line. Current thinking is that convection will increase in coverage/intensity overnight Tue night with pcpn coverage probably attaining likely criteria by or just before daybreak as warm front passes. Scattered to numerous convection likely to persist in warm sector before fropa/squall line passage early/mid-afternoon. Post-frontal lingering moisture should result in overcast through at least early-afternoon Thur, and possibly the entire day. Have worded the public forecast accordingly. A quick peak at the 06z NAM shows a slightly slower/less intense system overall w/ 500 mb hieght falls not quite as strong as previous run. Also, fropa is delayed slighty to about 22z. This should not require much in the way of changes in the 00z-based forecast package and will leave all the same for now. Later shifts will want to consider timing trends if nothing else.

Hazardous Weather

Hazardous Weather Outlook (Tuesday through Saturday): An intense storm system that is expected to stengthen over the plains later today and move toward the area. As it does, warm moist air will surge nortward ahead of the system and set the stage for a potential severe weather event. Strong low-level wind fields will support storms to become organized pose a threat of wind damage. Although damaging winds is expected to be the primary threat, large hail and isolated tornadoes will be possible. Thunderstorms should increase in coverage tonight and be scattered across the area into the morning hours on Wednesday. As the system passes later during the afternoon on Wednesday, a line of thunderstorms will likely sweep across the area bringing the highest threat for severe weather. The most likely time for this line to impact the area will be from early to mid afternoon. Residence should review severe weather safety information and be prepared to take action should severe weather threaten. Now is a good time to develop a plan of action if you do not already have one. Monitor a reliable weather source, such as NOAA Weather Radio, for the latest on the dangerous weather situation.

Astronomical and Climatological Data
Moon Phase Last Sunrise 6:17 AM Sunset 4:55 PM	11/14/06 Normal High Record High Normal Low Record Low Temperature 70°F 82°F (1955) 48°F 32°F (1986) November Normal Wettest Driest Precipitation 5.41 in. 13.65 in. (1948) 0.06 in. (1924)

11/14 in Mobile Area Weather History

In 1983 an early evening storm dropped an F0 tornado near Fulton in Clarke County, AL where a roof of a home was damaged and several trees were downed. (Data compiled from NWS Mobile, NWS Birmingham, newspaper articles, USA Archives, US Hurricanes and HurricaneCity.com)