Forecast 7/30/09

It has been a busy couple of weeks and I have had little time to keep a detailed forecast the last few days. However, I did sit down this morning and do a detailed hand analysis. Based on that, here is my forecast...

Synopsis:

The forecast area continues under NW flow with the passage of a cold front early this morning. NW flow appears to continue into the early part of next week. There is a cold front in the northern Rockies that will approach the forecast area early Saturday morning.

Discussion:

The morning convection has cleared the area to the SE and we are in for a quiet and unseasonably cool night tonight. Temps should rebound nicely on Friday before the approach of a cold front early Saturday morning.

NAM 18Z (4pm local) Temps and Wind for Saturday

GFS 18Z (4pm local) Temps and Wind for Saturday

The above images indicate that the NAM and the GFS are in pretty good agreement on the timing of the front which should be in the southern part of the forecast area by late Saturday afternoon. The real question is will we see any precip or storms from the frontal passage. Typically these setups start an MCS (Big Thunderstorm) up in the high plains overnight that dives down and hits the forecast area early in the AM. However, the GFS has an interesting take on the precipitation totals for the area on Saturday.

GFS 18Z (4pm local) 12 Hour Precip Totals for Sat

If the GFS is to be believed the MCS forms over KS as expected but falls apart just north of the forecast area and then fires back up in the southern part of the forecast area later in the day. I am not buying this however. I will wait for tomorrow's model runs before making the final call, but I believe we should expect some thunder and rain early Saturday morning. (Get a tee time for Sunday, not Saturday morning!)

Long Range:

Our couple of weeks of cooler than normal temps looks to be coming to an end as we move into next week. Temperatures should be more seasonal, lower to mid 90's early next week. August heat looks to really get going sometime around 8/6 (next Thursday). According to the long range GFS runs which are not that accurate, but have been doing a good job handling the NW flow event we have been under, the next cool down looks to be around 8/11.

12Z 200mb Hand Analysis

12Z 700mb Hand Analysis

12Z 850mb Hand Analysis

12Z Surface Hand Analysis

7/21/09 Forecast

Synopsis:

NW flow continues for NE OK with the passage of the cold front this morning. A cold front currently lies to the south and east of the forecast area with a surface low centered over north central AR. A very large MCS extends all the way from WI to the gulf coast and continues to translate east.

Discussion:

The passing of the cold front will moderate daytime temps for the next few days to below seasonal averages. However we should see a warming trend through the end of the week. Dew points will also continue to fall over the next 24 hours before beginning to recover in the Thurs time frame. Our next chance at cooler temps and precip looks to be in the Saturday to Sunday time frame as the GFS wants to bring a cold front into the area over the weekend. However, this one doesn't look to be as fast or as cool as the front this AM.

Long range models continue to show the area staying in a general NW flow for the next couple of weeks. However it looks as though the upper level trough may try to slide east for a bit and bring warmer temperatures in the extended period.

21Z Regional Surface with Radar:

12Z 220mb Hand Analysis

12Z Surface Hand Analysis

7/20/09 Forecast Verifies

Like many of you I woke up to the thunder this morning around 3:30AM. Looks like the forecast verified nicely. Tulsa did get the thunder and about 3/4" of rain while the main body of the precip stayed in SE KS, SW MO, and NW AR. I grabbed a storm rain total off GRLevel3 radar this morning. Image below:

7/20/09 Forecast

SYNOPSIS:

The NW flow continues over the forecast area for the time being. A warm front lies just over the Tulsa area running on a line from Woodward ok to Tulsa to Little Rock AR as of 21Z. There is a surface low sitting over SW KS with a stronger cold front anchored by another surface low over central NE. To complicate things, there is a trough of low pressure running from SW NE all the way down to the TX panhandle.

12Z Analysis (Note, the warm front has moved north since this morning analysis)

18Z Meso Analysis:

Discussion:

Dew points are through the roof in the area today making it feel much hotter than it is. Those dew points are the fuel which may aid in storm development this evening and overnight. Tonight's forecast is a little on the tricky side. The coldfront to our NW should dive south tonight and be the focus of an MCS (read big storms) that should dive from NE to the SE across KS and into NE OK during the overnight hours. The real question is how far south the MCS makes it. While the NWS TUL is bringing the storms all the way into the Tulsa area overnight, I think the latest GFS and NAM runs are going to keep it just to our north. While it is possible that we will get some thunder and rain overnight due to the MCS I believe the bulk of the rain and severe weather will stay in SE KS, far NE OK and far NW AR. Don't be surprised to hear mother nature's alarm clock at about 4AM tomorrow.

Prior to the main show late tonight, there is the possibility of storms firing just about anywhere due to the high CAPE numbers over the area with little CINH or cap. However, there will need to be some forcing for that to happen and a look at the radar as of 18Z doesn't reveal any outflow boundaries as areas of forcing at this time. That said, the trough of low pressure to the west could cause some storms to pop up west of Tulsa and make their way down the warm front in the early and late evening hours.

Tomorrow should be a pleasant day with cooler weather after we get the chance of storms out of the area. Look for things to warm up the next few days with a possibility of another cold front effecting the area toward the weekend.

7/19/09 Forecast

No hand analysis today, too busy with golf and what not. That said, the NWS TUL office wants to break out precip for most of the area tomorrow night into Tues morning. After a brief look at the 18Z NAM it looks like it may stay north of the Tulsa area, but then again maybe not. There is a pretty well defined surface short wave that seems to be riding the NW flow into the area. It is currently running from SD all the way to the TX pan handle along what NCEP is depicting as a stationary front. I think it is more of a pressure gradient than a front, but will wait for the surface plots tomorrow to make that call.

Like all NW flow events, it is all about the timing and we will will just have to wait till the AM to get a handle on that. Easier when this is a hobby, not a job...

Surface depiction with radar from 20CDT

7/18/09 Forecast

Not enough time to do a hand analysis today, but we did have some hit or miss showers which is to be expected in a NW flow setup. Looks like things should quiet down tonight and we are looking at a record low possibility. It is interesting how it still manages to warm up so quickly after those low morning temps though.

DA surface analysis:

7/17/09 Forecast

Synopsis:

Northwest flow aloft is holding the cold front / stationary front south of the forecast area. A east coast ridge continues to strengthen at 200mb. A surface low is sitting in SE CO and has helped to sustain and ongoing MCS from NW KS to south central KS.

200mb analysis, note the NW flow.
Discussion:

The cold front from last night sits just south of the forecast area and I expect it to turn into a stationary front that slowly retrogrades over the weekend. The good news is dew points should be down by about 10 degrees over the next few days which will make for a pleasant weekend. Looking forward into next week it looks like we will see a return to seasonal temps by mid week. Beyond mid week it looks as though the upper level ridge to the east will stay in place which should prevent a return to 100+ temps for a bit. This can be seen in the 7 day ECMWF depiction below.

While the weekend looks to stay dry, short waves in the NW flow will need to be watched to anticipate wet weather over the next 7 days.

12Z Surface analysis:
12Z NECP automated analysis with radar:

7/16/09 Recap

I got on a plane in Houston this afternoon and got to see the meso that laid some baseball hail on OKC from 34 thousand feet and 100 miles away on the way back to Tulsa. It was a pretty neat sight and it was interesting to see a supercell from that angle. I had checked the radar before boarding in Houston and was looking forward to the view. Here are a couple of pics I shot with my iPhone. Note I was at 34K feet and the top of the storm was pushing 50K feet. Also note the anvil which is blowing off to the SE. Can we say hello northwest flow? More on that later.

Now for my blown forecast from yesterday. The convection last night was the result of an outflow boundary that showed up from some earlier convection to the north in KS yesterday afternoon. Then we get the early morning stuff that woke me at 4AM which was OK as I had to get up at 4:15 to catch a flight anyway. What really threw off the whole forecast is a huge amount of boundaries that presented this afternoon. Check out this map I put together with a program called Digital Atmosphere.

Note that all the activity is not around Tulsa. Then take a close look to the SE of Tulsa and OKC. What you will see are little areas of blue that note outflow boundaries that are setting up. This is the result of storms that died hours ago and gusted out. We will likely see more convection tonight along these boundaries as they progress south.

BTW, the main event which is the cold front we are all waiting on is still in central KS. It should make it through the area tonight and if it happens to connect with a boundary we have a chance of more storms. That said, I am not optimistic for the Tulsa area. I think we will see an MCS to the west and one to the south. The good news is we will have very nice temps the next few days. More importantly, dew points are going to get knocked down about 10 degrees so you won't start sweating the moment you head outside.

Enjoy the next 5 days. Summer will return soon enough...

7/15/09 Forecast

Unfortunately today ended up being too busy to create a detailed forecast. I did complete a hand analysis so here is the short version. The upper ridge is shifting south and east over the next few days which will bring a NW flow to the area as I have been hinting at the last few days. The cold front that we have been waiting on has slowed down and now the best chances for convection (In NE OK and the Tulsa area specifically) look to be tomorrow late afternoon and evening. Which is not so good as I am supposed to be on a flight from Houston that lands at 5PM tomorrow!

Plan on some rain tomorrow night and possibly heavy rain a little thunder and lightening. Cooler weather for the weekend which means it is time to go play golf! Hope to have time to do a detailed analysis and forecast on Friday after I am back from my Houston day trip.

7/14/09 Forecast

Forecast Area: NE OK

Synopsis:

The upper ridge that has plagued the area for the past week is still firmly in place and will remain so for another 24 hours or so. The upper level high that was parked over central TX was moved west and is now sitting over the Big Bend region of western TX and southern NM. There is a warm front running from a surface low centered over the OK panhandle east across the OK/KS border and then running SE across NE OK and AR. The warm front appears to wash out into a stationary front from central AR to the SE. A trough of low pressure/stationary front extends from the surface low in the OK pan handle to an area of high pressure over northern CO. The news maker later this week will be a cold front that runs from the surface high to the NE across NE and SD.

Discussion:

Expect the hot temperatures to continue across NE OK this afternoon with Td's running in the upper 60's. This combination will continue to create high heat index values across the region. The far NE part of the forecast area will get a bit of a break due to the over night convection associated with the warm front. There is an OFB across far SW MO and NW AR that may serve as the focal point for another round of convection this afternoon, but do not expect that to effect the forecast area.

A continuation of down slope winds aided by warm 850mb temperatures and low Td's will crank up the heat across the western portion of the forecast area, but lower Td's will also moderate the heat index values. Expect strong winds from the south in the eastern portion of the forecast area veering to SW winds further to the west.

The 12Z GFS continues to depict the warm front moving north over KS over the next 24 hours before being over taken by the cold front some time in the Wed evening time frame. Depending on the timing there is a chance for convection in the forecast area Wed night. Best chances for storms seems to be in the Thurs morning to Thurs day time frame as the cold front moves across the forecast area.

Expect temperatures to moderate to more seasonal levels post cold front. Also, the upper level ridge should break down during this period and put the forecast area in a NW flow aloft. This will increase rain chances through the weekend into early next week.

Long story short, we have just two more hot days before we get a much needed break!

7/13/09 Forecast

Forecast Area: NE OK

Timing and storm mode:
Convection should initiate after 2PM to the NE of Tulsa on a line from Bartlesville OK to Tahlequah OK and to the south. Expect cells to initially be discreet with storm motion to the SE at around 15mph.

Synopsis:
The dominate feature at this time is a strong upper level ridge running from ND to the Mid Atlantic states. There is also a upper level high centered over central TX. Down slope winds of the rockies continue to pump heat into the region. A cold front along the OK/KS border running to the SE through central AR has been the focus of overnight convection.

Discussion:
Temperatures will hover around 100 in Tulsa today with slightly cooler temperatures to the NE due to the influence of the overnight convection and the associated cold front. Expect the front to remain relatively stationary and to slide to the east overnight. Dew points are in the 70’s across NE OK falling off into the upper 50’s across western OK due to the down slop winds and dry air aloft over western OK. The morning soundings show a 13-15 degree difference in dew point depressions from S KS across NE OK into central AR as compared to central and western OK.

Elevated dew points and daytime heating are creating CAPE values in excess of 8000 according to the 16Z run of the RUC. The RUC also depicts the cap breaking by early afternoon near western AR and eroding back across NE OK over the afternoon hours. The focus of any convection will most likely be along an outflow boundary that is visible on satellite and NWS radar at this hour.

There is relatively little shear for these storms to work with so do not expect much in the way of severe weather. Surface to 500mb cross over is close to 180 degrees in the area with the best instability, therefore it may be difficult for storms to sustain themselves. However, the best chance for severe storms will likely be over far eastern OK to central AR.

Expect storms to diminish this evening with the loss of daytime heating. Good news later this week as the upper ridge appears to break down by Wednesday evening bring NW flow and cooler temps and rain chances to the area. More on that tomorrow…

It is hot!

It has been a crazy year weather wise. A spring that never materialized (read no great storm days) turned into a hot humid summer. Looks like we are going to be under an upper ridge for the next week so no relief there. One nice thing about working with weather maps is you can tell where you don't want to be (117 in Enid) and where you would like to be (55 in N CO)!