textproduct: Columbia

SYNOPSIS

Cool and cloudy conditions continue today with below normal temperatures. Dry conditions are then anticipated for the mid to late week period with near to slightly below normal temperatures. A colder air mass may move in behind a dry cold front early next week.

NEAR TERM /THROUGH TONIGHT/

Key message(s):

- Cool and dry, clouds clearing this afternoon

Clouds have held in longer than most models projected leading to temps in the upper 30s to low 40s through mid day. Now that we are beginning to see some clearing, which will continue through the afternoon, those temps should jump up a bit into the mid 40s to upper 40s for highs. With high pressure moving directly over the region, winds will be light and variable through the day. Tonight, expect below normal temperatures in the mid to upper 20s. The HRRR which had a better handle than most models on the low clouds through the morning shows redevelopment late tonight. This could hinder cooling during the early morning hours on Wednesday.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/

Key message(s):

- Breezy for Wednesday as a dry front moves, followed by below average temps.

As strong low pressure system cuts through the Great Lakes, an associated surface front will drag across the Appalachians on Wednesday. The pressure gradient will notably strengthen by late morning and drive some gusty southwest winds throughout the day, along with completely clearing out any residual low stratus. Gusts to around 35mph are expected in the afternoon and a Lake Wind Advisory is out from late morning into the evening. With PWAT's down below 0.75" and limited forcing, this front will be dry as it moves through in the evening. Dry high pressure will then build in for Thursday behind this front with below average temps returning, despite sunny clear skies; 1000-500mb thicknesses will be around 540- 535dm, so a modest shot of cold air pushing in.

LONG TERM /FRIDAY THROUGH MONDAY/

Key message(s):

- Moderating temps through Saturday before a strong, but dry, front arrives late in the weekend.

The trough that digs in Thursday will steadily flatten out as weak surface ridging pushes into the area. Temps will steadily moderate to right around average, in the 50's and low 60's with PWAT's too low for any precip. A strong digging trough is the next notable weather maker which will approach the area Sunday. Strengthening southwest flow and some persistent moisture advection could help pop a few showers across the area Sunday ahead the surface front, but widespread rain looks unlikely. The front will then push through sometime late Sunday with a strong cold advection regime behind it; temps will then run below for the early half of next week. The ensemble guidance however is in a state, with great discrepancies in how far south this cold, shallow airmass can make it. The NBM 25- 75th percentiles for morning lows on Monday ranges from 17-34 F and then similarly again for Tuesday morning. So, it will take some time for the ensembles to come into better agreement on how this cold airmass will progress.

AVIATION /17Z TUESDAY THROUGH SATURDAY/

MVFR/IFR ceilings possible early Wednesday morning

High pressure over the region will keeps winds light and variable through today. The HRRR, which verified well with stratus over the past 24 hours, is indicating the potential for stratus/strato cu to build back in tonight as SW winds develop. This will likely lead to a period of MVFR or possibly IFR ceilings around 12Z. We are expecting restrictions to be short lived however as the pressure gradient tightens and winds begin gusting around 15Z. SW wind gusts above 20 kts are likely through the afternoon with gusts up to 30 kts possible.

EXTENDED AVIATION OUTLOOK...Dry air will hinder widespread restrictions through much of the extended, but localized fog along river valleys will be possible some mornings.

CAE WATCHES/WARNINGS/ADVISORIES

SC...Lake Wind Advisory from 10 AM to 11 PM EST Wednesday for SCZ016-018-020>022-025>031-035-037-038-041-115-116- 135>137. GA...Lake Wind Advisory from 10 AM to 11 PM EST Wednesday for GAZ040-063>065-077.