Fri Aug 28

Past day verification and analysis: No precip high 94 low 72. Precip coverage was less than 30% likely due to dry air aloft along with capping inversion around 650mb. Will take that into account in future forecasts.

Synoptic analysis: A closed low in the deep south will open up and converge with Tropical Storm Danny. Thunderstorm chances will increase this afternoon. A chance of storms will continue on Saturday. A cold front will begin to push into the region on Sunday and stall early next week providing a good chance of showers and thunderstorms. Cooler and drier conditions will invade the region by next week.



Near term (12 hr): A very interesting but fairly difficult forecast. The closed off upper level low will become an open wave and converge with Tropical Storm Danny. The juxtaposition of these two features will create a dynamic and complicated scenario this afternoon. A zone of surface convergence should set up near the piedmont later this afternoon. Upper level support isn't too impressive... still anticipate likely chance for convective development this afternoon. Precip on the wet side of Danny's circulation is hardly in existence with westerly shear having sheared most of the precip to the east of the center... therefore am less concerned with direct precip from Danny. Breaks in the cloud cover should enhance SBCAPE above 2000 J/Kg by this afternoon. PW values of 1.8 to 1.9 inches are currently in the region. There is also no sign of a capping inversion therefore expect storms with heavy rain to develop along regions of convergence. Will go likely PoPs this afternoon and high chance overnight. High around climatology due to cloud cover and low slightly higher than persistence due to the same reasoning.



Short term ( 12 -60 hr): Attention will shift from tropical storm Danny and the upper level low in the south toward the strengthening and transient upper low near the great lakes. A relatively strong cold front will approach the area from west increasing rain chances through Sunday afternoon. We have a good chance for storms Saturday afternoon being in the warm sector. A 500 mb impulse will move through Saturday night therefore will keep high chance PoPs through the night on Saturday. Will go with climatological high and persistent low. Cloud cover and showers will impact lows. Will lower PoPs on Sunday to high chance. Increased shear will improve storm organization, but most of the upper level dynamics will be to the west. Severe threat will increase but not enough to warrant anything other than a mention at this time.


Long term (Beyond 60 hr):

Trough will deepen and the cold front will stall and weaken in the early part of the week bringing a chance for showers and storms on Monday and Tuesday before slowly moving past the region. Will go high chance on Monday and Tuesday. Once confidence grows in the timing of the front and upper level support. Autumn weather will invade the area after the passage of the front through the end of the week.

Forecast:

Friday afternoon: 60% chance of storms with heavy rain possible at times. Precip .25 inches but higher in storms. High 86

Friday night: 40 % chance of showers and storms.. precip less than .1 inches

Saturday: 40 % chance of showers and storms through the night.. precip less than .1 inches High 89 low 72

Sunday: 50 % chance of showers and storms mainly before 10 pm.. precip .1 - .25 inches High 89 low 72

Monday: 40% chance of showers and storms after 2 pm High 85 low 72

Tuesday: 40% chance of showers and storms through the night. High 85 Low 72

Wednesday: Mostly cloudy in the morning partly cloudy in the afternoon High 81 Low 65

Thursday: Partly Cloudy High 79 Low 60

Review of RAH AFD: Need to watch for dry air on Saturday. Keep a good eye out on upper divergence as well. A lot of stuff to look at through with a full forecast. RAH breaks it up into several sections. Precip early next week may be some overrunning. When looking at theta e to determine position of front need to consider that part of the hold up is due to downsloping effect. So I need to look at the pressure field and wind direction to determine if front has passed.