Alan's Thursday Mid Morning Weather

Thursday, September 13th 2007, 4:15 am
By: News On 6

Noon Update: So far, so good. Humberto moving through Louisiana at this time and keeping most of the moisture well to our south and east. Alan mentioned the cold front which still looks to be arriving during the morning hours of Friday. Not much moisture for it to work with so keeping his slight chance of rain on Friday. Pressure gradient suggests rather blustery N winds and locations behind the front may struggle to reach the forecast, have dropped them a bit. Otherwise, not much in the way of any changes.....


From 9:18 AM:
I have noticed mid 60 dew points arriving from North TX into southeastern OK as pressure falls to our northwest. This is matching nicely with forecasted values of increasing low level moisture this afternoon across the Red River Valley. A few showers or storms will remain in the forecast for areas south of I-40 as a weak mid level wave draws near the area along with maximized daytime heating. This activity should not impact Tulsa.

Our front arrives Friday and will be able to generate some scattered showers or storms along and even behind the boundary. The big question remains as to how much coverage we should have on the map. This past week I have used a 30% coverage, but lowered to 20% early this morning. I should have stuck with the 30%, but no changes will be made to the forecast at this hour.

The 06 incoming Nam offered some pops across southern Kansas Sunday morning in response to moisture increasing back into the area Sunday morning and a weak impulse traveling in the northwest flow aloft. This is something to watch, but I’ll keep the extended also unchanged from previous days.

Dick will be in the office around to update you later today.

Alan Crone

From 4:15 AM:

Good morning!

Humberto is to our south. An upper level wave is just west of our area this morning, with a cold front located in the central U.S. All of these features will have a supporting role in our weather for the next few days. Humberto may actually spread a little moisture into far southeastern OK late this afternoon. Concurrently the upper level system to our west will slide eastward and may help to initiate a few showers or storms in far southeastern OK. The front to our north will arrive Friday morning across northeastern OK then slide to the I-40 corridor around 1pm, then to the Red River Valley around 7pm or so.
Moisture Friday is not expected to be sufficient for wide spread showers or storms. I’m trying to keep my 30% coverage Friday, but may drop this down to a 20% pop. I’ll make this decision near the 5am air time.

NAM data is attempting to pool dews from 65 to near 70 along the I-44 corridor Friday in advance of the front. This seems a little overdone to me, but some mid 60s would be possible if Humberto scoots a hair east. If so, then a 30% pop would be justified. Low level moisture is pushed southward through Saturday midday, but makes a quick return Saturday night into Sunday as pressure falls occur along the Front range in advance of the next system.

We have some differences in model data, more so with the solutions regarding the position of a surface ridge of high pressure Saturday. This would have ramifications for clouds and temperatures, but I think our forecast is in the ball park regardless.
Saturday relatively cooler and drier air will filter into the area for day before warmer air begins arriving Sun into early next week as the upper air pattern begins to transition.
Next week will be dominated eventually by a significant trough in the west while our mid level ridge will attempt to suppress thunderstorm activity in the southern plains through Wednesday. From the middle of the week to next week, the pattern alone with suggests at least a chance for some showers and storms, and that will probably be the case.

Need to run.
See you soon!

Alan Crone