Wednesday, October 3, 2007

Latter Week Forecast -- Severe Weather Possibilities

To start off, the Des Moines NWS and the Quad Cities NWS have issued their statements on the tornadoes that occurred yesterday in Iowa. The tornado in Des Moines & Seymour were both given EF1 ratings, their reports can be found here. The other tornado in Iowa occurred in Keokuk county nearest to the town of Delta, this one was also given an EF1 rating. The specifics for that one as well as the tornado in Scotland county, MO are given on the Quad Cities NWS page.

A nice day today however behind the front with mid 70s to near 80 degrees for the highs across the state. Tonights' lows won't drop nearly as low as last nights as the southerly winds in the lower levels will continue to bring up moisture, upper 40s in eastern Iowa to the mid 50s in western Iowa are forecasted. Highs tomorrow should range from low to mid 80s with the southerly winds continuing to pump in warm and moist air for this weekend. This can easily be seen in Thursday night lows as they will be limited by the dew points, range of lows should be near 60 to the mid 60s in southern Iowa.

Thursday evening and early overnight will bring the first round of severe weather that will be possible over northwest Iowa. The strong lower level winds will continue to increase the moisture return to the north, this will also aid in the development of a warm front over the area. The nose of the low level jet will likely be the focus of thunderstorm development, mainly elevated during the overnight hours. These thunderstorms do have the possibilities of becoming severe, with large hail being the main threat. Isolated shower/thunderstorm may last overnight and into the morning hours for northern Iowa, although they should clear out of the area with time.

Friday's highs will be well above normal and within a few degrees of records in the warmth can really spread to the north. Lower 80s in the north where some clouds may linger near the warm front will keep them from flirting with near record warmth. However from Sioux City to the Quad Cities and points southward, highs will likely range in the mid to upper 80s! The dew point will also remain high, leading to quite muggy conditions for this time of year. Lows overnight will be wonderful, ranging from mid to upper 60s!

Currently areas of northwest Iowa are currently under a slight risk for Friday evening/night as well, including a hatched area where significant severe weather may be possible. This threat however is still questionable as the warm front will likely be well north of the state. We'll likely be relying on the low pressure system that will be developing over eastern Nebraska. This system is currently getting strong wording from the SPC, indicating that with such strong shear values and instability, along with a stout capping inversion that will be in place where storms can initiate they may have the ability for some extremely large hail and potentially strong tornadoes. This is very strong wording for an event this far out, so it will definitely deserve to be watched as it unfolds.

The weekend may also hold more severe weather potential as a deep trough move out of the west and onto the plains. A coinciding low pressure system will also develop int he lee of the Rockies and move into the western Plains for Saturday and Sunday. This feature in the forecast is also quite difficult to pinpoint at this time, but given the strong heating and moisture that is likely to be in place along with some impressive shear values it is undoubtedly looking like some areas of the plains will be in good shape for severe weather. This will likely be my focus of the next several updates, with the potential for several severe weather and chase opportunities on the weekend.