textproduct: Columbia

SYNOPSIS

Cool and mostly dry conditions are expected today, though a few showers are possible along and ahead of a cold front this afternoon and evening. A period of moderate to heavy rainfall is expected with the next storm system Monday night into Tuesday. High pressure then builds back in for Wednesday and Thursday before another system may take aim at the region to end the week.

NEAR TERM /THROUGH TONIGHT/

Key message(s):

- Increasing moisture with isolated showers possible - Cold front crosses the region overnight

A shortwave moving through the TN Valley is driving a cold front slowly toward our area with regional radar showing an area of scattered showers moving through the Upstate. Moisture will continue to increase as moisture advection shifts eastward ahead of the front and PWATs are expected to rise to around an inch just ahead of the front by this evening. The front is expected to slowly move through the region overnight with chances of rain best across the western and northern Midlands and upper CSRA this afternoon and evening, although no significant rainfall is expected, generally a tenth of an inch or less. Temperatures were slow to rise earlier due to cloud cover but some clearing across the eastern half of the area has allowed temperatures to surge into the mid and upper 50s already over the eastern Midlands while the western Midlands remain cold under cloud cover with mid 40s at Newberry. Highs today should range from around 50 to lower 50s west to the mid 60s east.

Expect quite a bit of cloud cover tonight with the front moving through and winds gradually shifting more to the northeast behind the front. This should limit radiational cooling and overnight lows expected to be warmer ranging from the upper 30s northwest to mid 40s southeast.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/

Key message(s):

- Cooler and drier on Monday with a low (10 to 20 percent) risk for a few light showers until rain chances rapidly increase towards evening.

- Widespread moderate to heavy rainfall moves in Monday night into Tuesday morning with precipitation tapering off from southwest to northwest in the afternoon.

- Skies clear out Tuesday night as high pressure builds in.

Monday and Monday Night: High pressure passes north of the region pushing cold, dry air down the spine of the Appalachians in a classic in-situ wedge setup. Expect mainly cloudy skies and cooler temperatures. While much of the day should be dry, a bit of drizzle or a few light showers cannot be ruled out, especially in the CSRA. Temperatures will be cooler than today with forecast highs generally in the 50s, with some upper 40s possible in the far northern CWA. Low pressure in the Western Gulf rapidly moves northeast and ends up near or off the South Carolina coast by daybreak Monday. The rain may be heavy at times towards daybreak. The clouds and rain limit cooling with lows ranging from the mid-30s to mid-40s.

Tuesday and Tuesday Night: Widespread moderate to locally heavy rainfall should be ongoing at the start of the day aided by an approaching upper trough, deep isentropic lift, and a robust low-level jet. While the forecasts is calling for rainfall amounts between 1 and 2 inches, the overall flood threat is low though some minor flooding cannot be ruled out in locations where the heaviest rainfall occurs. Rain chances diminish from southwest to northeast during the afternoon and evening hours. Skies clear out at night as high pressure builds in from the west. Daytime temperatures should once again end up in the 50s in most locations, with a few lower 60s possible across the southeastern CWA. Clearing skies at night should promote radiational cooling allowing temperatures to drop into the upper 20s to mid-30s.

LONG TERM /WEDNESDAY THROUGH SATURDAY/

Key message(s):

- Mainly sunny but cool on Wednesday.

- Warmer Thursday with increasing cloudiness.

- Rain chances return to close out the extended.

High pressure passes overhead on Wednesday bring cool, dry weather conditions to the FA. The anticyclone will pass offshore by daybreak Thursday promoting moisture and warm air advection across the FA, though temperatures will likely remain below seasonal values. Clouds should increase during the day ahead of the next storm system, which will begin to take shape over the Western Gulf. Rain chances increase Thursday night into Friday and there is the potential for another round of moderate rainfall to close out the extended, though confidence in timing is low. Temperatures should warm enough Friday morning to prevent any frozen precipitation at the onset of the event, though trends will be monitored. Below normal temperatures are likely to persist through the long term.

AVIATION /16Z SUNDAY THROUGH THURSDAY/

Generally VFR conditions expected through the 24hr forecast period.

A cold front will approach the area this evening and move through overnight. Moisture continues to increase through the evening with isolated showers possible ahead of the front but confidence is limited in impacts at the terminals as much of the rain may stay north and west of them. Earlier MVFR cigs have eroded and VFR cigs around 5kft to 10kft are expected through the afternoon with some possible MVFR cigs with rain showers that will be included in a Prob30 group all but OGB. Generally light and variable winds around 5 knots or less through this evening until the front passes then winds should shift more northeasterly by morning and increase to 5 to 10 knots after 15z. There is some possibility of a return to MVFR cigs, favoring AGS/DNL, 12z-16z time frame but confidence is limited so not including in this forecast.

EXTENDED AVIATION OUTLOOK...The next weather system early in the week will keep the potential for restrictions in rain Monday and Tuesday, with highest likelihood of rain on Tuesday. Additional restrictions possible late in the week.

CAE WATCHES/WARNINGS/ADVISORIES

SC...None. GA...None.