Tracking Rain Systems

Thursday, November 20th 2014, 4:37 am

By: Alan Crone

The focus of the forecast remains centered on two systems approaching our area that will bring some precipitation chances back to the region.   The first weak wave nears the area late tonight into Friday morning with some drizzle or spotty showers across eastern OK. The second and stronger wave will near the state Saturday bringing rain and thunderstorms back to eastern OK. Some pockets of moderate to heavy rainfall is possible Saturday across southern and south-central OK.   This storm system may linger for a few hours Sunday morning before exiting far eastern sections of the state.

A weak front cleared the area yesterday with little impact on the daytime highs. Temps moved into the mid and upper 50s yesterday with sunshine and light north winds.   This boundary, located to our south this morning, will slowly advance northward later tonight into Friday morning as our first wave nears the region. Moisture is expected to flow up and over this boundary into southern OK and northeastern OK resulting in areas of drizzle of spotty showers by Friday morning to midday. This chance will remain around 30 to 40%, but locations across the Tulsa metro may see a damp start to Friday with the very light precipitation over the area.

The second and stronger wave will be rapidly diving down the Pacific coast and turning inland Friday.   Moisture from the Gulf of Mexico is expected to quickly surge northward Friday night resulting in numerous showers and storms across central and northern Texas by late evening. Saturday morning the main upper level system is moving eastward across northern Mexico with abundant moisture advecting into southern and eastern OK resulting in wide-spread showers and thunderstorms. Some severe weather is possible across central Texas with some pockets of moderate to heavy rainfall a possibility across southern OK. Even though moisture profiles are extremely high for this time of year, I don't think flooding will be a big issue with this system even though some local street level issues may occur across southern OK.

This system will move eastward late Saturday night into Sunday morning with a few showers “wrapping around" the back side of the departing trough for a few hours early Sunday.   The upper air flow will remain positioned to bring another cold front into the state Sunday night into Monday with gusty northwest winds and slightly cooler air.   The arriving air-mass, while colder, does not appear to be of arctic origin. We'll keep our numbers in the upper 40s and lower 50s for highs early next week.

As posted here yesterday, the end of next week in the data offers little confidence. The EURO continues to bring another trough into the state with rain chances Friday and possibly some colder air allowing for wintry precip Saturday. The GFS is now suggesting a surface front could move into the area Thursday, but offers little in the way of precipitation.    All of this is creating high uncertainty for one of the biggest travel and shopping Holidays-weekends of the year. If you have travel or shopping plans for the Thanksgiving Holiday, you are encouraged to remain aware of the forecast as we unravel this data for the end of next week.

Temps today look fine with highs in the mid-50s along with sunshine until later in the day. Enjoy the weather! But throw the rain gear into the truck for Friday and more so Saturday.

Thanks for reading the Thursday Morning weather discussion and blog.

Have a great day!

Alan Crone

KOTV