Wednesday, January 16, 2013

Winter Weather Recap and End of the Week Forecast


Recap of Last Night:
The forecast for last nights winter weather event was somewhat a challenge at times. A change in degree here or there really can mean the difference between an ice storm and rain. Last night, Bowling Green temperatures reached freezing later into the event. We saw some icing on elevated surfaces such as signs, hand rails, and car tops but nothing substantial. Areas as close as one county over in Butler County received more significant icing. The location of the freezing line (line of change over from rain to mixed wintry precipitation) was the saving grace for Warren County last night. This line stayed mostly off to our west which meant that most of our precipitation changed over to rain with only a short period of some freezing rain and sleet for parts of far western and northwestern Warren county.

Image taken from Tempestchasing.com. A great depiction of the location of last nights freezing line at 6 pm CST.


The most icing reported from downtown BG was only a thin coating on hand rails, car tops, and street signs. The trees and bushes in my area remained rain coated with no visible icing. While not as favorable for pictures sake, a huge near miss in the way of headache and danger.


Forecast Discussion for 1/17-1/20:
A strong upper level low located over Texas, Arkansas, Louisiana looks to advance northeast over Mississippi and Tennessee Valleys throughout the day Thursday. A surface low is forecast to begin development Thursday morning and become more organized over the border of Georgia and South Carolina by 18z (12 pm CST). This surface low will then advance northeast along the Carolinas. Far eastern Kentucky will remain on the cold side of this low (where colder air is the dominate advection). This will provide a chance for a light wintry mix event to occur in far southeastern Kentucky. 

09z ( 3 am CST) 1000-500 thickness MSLP and precipitation showing surface low development over GA/SC border.

Moisture looks to be sufficient for showers to develop as the low pressure system brings southeasterly winds and gulf moisture up along the cold frontal boundary extending from Florida to the Carolinas into the Atlantic.  HRRR High Resolution Rapid Refresh model shows a broad swath of precipitation from Mississippi to Northern Kentucky throughout the day Thursday. As the surface low develops, the heavier precipitation is shifted northeast as the low advances northeast.
24 hr forecast snow fall totals ending at 6 pm Thursday (CST). Shows far eastern KY in the 80% range for > 1 in with majority of eastern KY in the 30-75% chance of > 1 in.
Warren County could see a few light rain showers from this but no mixed precipitation is forecast though a few occasional flurries cannot be totally ruled out. Most wintry mix should stay to the east of Warren County. Any showers would be in the early morning clearing out later on in the day. Clouds should recede as well as the low pressure system passes to the east allowing some sunny skies to poke through after lunch time and into the afternoon as surface high pressure moves in behind. Partly sunny skies will be the trend into the weekend as we wait on our next significant weather system into early next week as another upper level trough becomes dug out from a jet max out of Canada. This system will bring the clouds and precipitation back into the Ohio Valley. Once under the influence of surface high pressure, temperatures will be slightly warmer into Friday and the weekend with highs in the mid to upper 40's even reaching the 50's by Saturday as our surface winds become more southwesterly.

NAM forecast surface temperatures for 18z (12 am) Saturday.

Forecast Overview:

Thursday 1/17: High, 43. Low, 24 . Northwesterly winds peaking between 5-10 knots. Slight chance of light morning showers. Clearing for some peak through sunshine into the afternoon with temperatures warming up. Mostly clear and cool night.

Friday 1/18: High, 43. Low, 26. Winds shifting to the southwest during the day. Mostly clear with few clouds. Winds peaking at 3-5 knots. 

Saturday 1/19: High, 50. Low, 32. Mostly clear and sunny and and overall beautiful day!

Sunday 1/20: High, 37. Low, 25. Clouds increasing into afternoon. Winds shifting more southerly. 

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