textproduct: Columbia

WHAT HAS CHANGED

Updated Key message 1 part of discussion for current conditions and expected timing of rainfall through the night. Aviation updated for 00Z TAFs.

KEY MESSAGES

- 1. Significant and beneficial rainfall expected tonight and through much of Saturday.

- 2. Cooler than normal temperatures this weekend followed by a significant warmup next week. Unsettled weather returns by the middle of the week.

DISCUSSION

Key Message 1: Significant and beneficial rainfall expected tonight and through much of Saturday.

Area remains sandwiched between two fronts, with one stationary front situated across northern Florida, and a cold front moving slowly into the central Appalachians. Between these boundaries, moisture will continue to be on the increase this evening and throughout the nighttime hours. Still expected to see a few scattered light showers possible over the forecast area, with slightly higher coverage across the southern CSRA and southern Midlands between now and Midnight. Later tonight and area of low pressure is forecast to develop along the Gulf frontal boundary and be moving eastward. Meanwhile the cold front will still be slowly pushing southeast and out of the mountains into Saturday. Aloft, a deepening trough pushing into the southeastern U.S. will help to bring moisture northward as the Gulf low strengthens along the front. Pwat values early this evening range from just below an inch over the northern Midlands and the Pee Dee, to around 1.25 inches over the southern Midlands and CSRA. With the moisture increasing, pwats will rise to around 1.5 inches in several areas as the deeper moisture moves in. This should set up a rather good over- running rainfall event starting late tonight and lasting through the early afternoon hours Saturday. Rainfall totals ranging generally from 0.5 to 1.25 inches, with isolated totals of 1.5-1.75 inches still appear possible, especially across our southern counties. Rain should be moving off to the east by Saturday evening.

Given the extent of the current drought conditions across much of the area, this is going to be some welcome rainfall and should be falling at a perfect rainfall rate as well to help it soak in more instead of resulting in total runoff. This won't end the drought by any means but it will help keep things from getting worse for the time being.

Key Message 2: Cooler than normal temperatures this weekend followed by a significant warmup next week. Unsettled weather returns by the middle of the week.

A pretty typical, albeit initially cool, pattern for spring is forecast to setup heading into next week. High pressure should translate into the southeastern US on Sunday and Monday, with dry and cool air settling into the area. Highs will likely be in the 70s both days, yielding some of the better weather of the spring so far. Thereafter, an unsettled pattern will continue. The jet stream looks to situate across the southern tier of the US for the next week or two, continuing to offer up chances at rain and storms. Our next system should approach Wednesday night and Thursday with a warm up & increasing chances for showers and storms associated with it.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/

Conditions will gradually deteriorate this evening as widespread rain overspread the terminals. Ceilings are expected to lower from MVFR to IFR overnight and persist into Saturday morning.

High cirrus will continue streaming in from the west ahead of a developing low pressure system. A few light rain showers are currently over areas to our south and east, but are mainly confined along the coast. Widespread rainfall arrives late tonight, mainly after 04-06Z, spreading from southwest to northeast. With this, ceilings will gradually lower to IFR by the early morning hours on Saturday. While rainfall should generally remain light enough for only modest visibility impacts, brief periods of reduced visibility are possible. IFR conditions are likely to persist through much of the Saturday as low ceilings and rain continue through the afternoon. Northeast winds will prevail through the TAF period, with occasional low end gusts of 12-15 knots possible. Gradual improvement is expected Saturday evening as precipitation tapers off and ceilings begin to lift after 20-22Z.

EXTENDED AVIATION OUTLOOK...Periods of restrictions likely continue into Saturday evening as widespread rain overspreads the region. Drier conditions then are expected Sunday and into the early week.

CAE WATCHES/WARNINGS/ADVISORIES

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