textproduct: Wilmington

WHAT HAS CHANGED

Slight increase to precipitation chances today. Increased confidence for accumulating snowfall - along and south of I-71 Saturday into Sunday. Higher confidence in very cold temperatures this weekend into the upcoming workweek.

KEY MESSAGES

1) Light precipitation and gusty winds expected today.

2) Very cold conditions expected Friday through early next week, with snow possible Saturday into Sunday.

DISCUSSION

KEY MESSAGE 1...

Surface high pressure will continue building off the east coast as weak low pressure tracks from the Mid MS Valley this morning thru the Great Lakes today. There will be a tightening pressure gradient between retreating surface high and the weak area of low pressure.

Southwesterly low level jet moves into the region this morning and strengthens to 55-60 kts. In warm advection flow, wind gusts of 25-30 knots appear likely, with a chance of a few gusts to 35 knots, especially across the northern counties.

Moisture is initially lacking but forcing leads to saturation and precipitation. Much of this will be in the form of snow, boundary layer temperatures will likely be warm enough for rain to mix in across parts of the CWA, mainly the south and southeast. Precipitation amounts are fairly light across the model solutions, suggesting snow accumulation will be limited to several tenths of an inch. The depth of the moisture is limited, and does not coincide with the DGZ for much of the event.

KEY MESSAGE 2...

There is high confidence in a return of arctic air and very cold temperatures from Friday into the upcoming work week. A strong (1050) Canadian high will sink down into CONUS bringing a potent polar airmass to our region. Temperatures will fall to well below normal, with ambient air temperatures in the single digits and teens for several days straight. The coldest day of the timeframe is forecast to be Friday night into Saturday. Exact numbers may still change, but blended guidance has been pretty consistent painting wind chills in the negatives across the CWA during that overnight frame.

In addition to the very cold temperatures this coming weekend, a very robust weather system will be moving across the southern US with the potential to cause significant impacts as far north as Kentucky and southern Ohio. A trough over southwest CONUS will begin to advect plentiful moisture out of the Gulf into the Tennessee Valley region. Meanwhile, closer to home, we'll be under the right entrance region of a potent jet Saturday night into Sunday, providing plenty of lift.

Confidence is slowly increasing that we will likely see some accumulating snowfall in our northern Kentucky/ southern Ohio counties Saturday into Sunday. We do have HIGH confidence that p- type will be snow, given the arctic airmass in place. However, it is still way too early to be looking at accumulation and caution should be exercised with any snowfall maps posted this early out. For example, in the last 24 hours, the blended guidance has painted anywhere from 1-3 inches to 8-11 inches over our southern counties between runs. Wild swings like this over short periods of time indicate HIGH uncertainty and unpredictability. Thinking remains the same in that the big questions still to be answered are how much moisture from the south can be transported north into our area, overall storm track, and timing/onset of precipitation. Then of course, once we nail down these details a bit more, we will begin to look closer at SLRs, snowfall rates, depth of the DGZ and more. Much still to be determined.

After this system passes, there still appears to be a signal for a prolonged period of very cold temperatures, with temperatures well below average forecast for the coming working week.

AVIATION /06Z WEDNESDAY THROUGH SUNDAY/

A low level jet develops ahead of a shortwave and a weak surface low tracking thru the Great Lakes today. A period of low level wind shear will develop toward sunrise and continue to late morning when better mixing develops.

Clouds increase and lower to a VFR deck between 4000 and 6000 ft late tonight. Some light snow is possible as this moisture and weak lift develops with MVFR ceilings after sunrise. Have a mention of prob30 for this chance.

MVFR ceilings to continue into the afternoon with the potential for a period of IFR after 18Z. The better threat for IFR conditions looks to occur across the eastern TAF sites. Expect MVFR ceilings to continue into this evening with some improvement to VFR from the west-southwest late in the evening into the overnight hours.

OUTLOOK...Snow and IFR conditions is likely Saturday night and Sunday, with the greatest threat along and south of I-71.

ILN WATCHES/WARNINGS/ADVISORIES

OH...None. KY...None. IN...None.