textproduct: Charleston

WHAT HAS CHANGED

All sections have been updated.

KEY MESSAGES

- 1) Patchy fog will be possible across the area late tonight and early Friday.

- 2) Unseasonably warm temperatures expected through the late week, with scattered showers and a thunderstorm, or two possible on Friday.

DISCUSSION

KEY MESSAGE 1: Patchy fog will be possible across the area late tonight and early Friday.

The forecast area will sit in the warm/moist sector ahead of an approaching cold front tonight. Light southerly flow this evening will continue through tonight and forecast lows are only in the mid to upper 60s for much of the area. Such values would be 15+ degrees above normal for early November. These temperatures, combined with similar dewpoints, will produce nearly saturated conditions in the presence of light to calm surface flow. Model guidance is mixed regarding coverage and intensity of fog. Most guidance sources suggest visibilities mostly in the 3-5 mile range, though there is some statistical guidance depicting some potential for lower visibility. Probabilistic guidance from the 05/12z REFS is being partially discounted along the SC coast and southeast SC because it appears to be initializing with sea fog along the coast and then allowing it to advect inland within the southerly flow. NBM probabilities are considerably lower and seem more reasonable for most of the forecast area. Overall, the current expectation is for patchy fog with visibilities mostly in the 3-5 mile range mostly for locations inland of the I-95 corridor.

KEY MESSAGE 2: Unseasonably warm temperatures expected through late week, with scattered showers and a thunderstorm, or two possible on Friday.

A cold front extending across the Ohio River Valley continues to track eastward towards the region. This will allow some isolated showers to form out ahead of the front across portions of the region as the front makes it's way towards the coastline. As the front inches closer tomorrow, expect a weakening broken band of showers with a couple embedded thunderstorms to track along with it through the region in the early morning/afternoon hours. There is an extremely low severe potential with this system as the environment remains unsupportive. Also, significant rainfall does not seem to be in the cards as well. Rainfall totals will range from 0.10 to 0.25 inches with 0.50 inches possible in some spots where the axis of higher instability develops (which appears to be along the coastline). The front should push offshore in the evening hours and drier, cooler air will make a return with a rain-free forecast in place through early next week.

On another note, temperatures will continue to be unseasonably warm this afternoon and tomorrow before the cold front passes through the region. Expect afternoon highs to reach into the low to mid 80s. These values are around 10 degrees above early November normals and are within a few degrees of records (see climate section below).

AVIATION /00Z FRIDAY THROUGH TUESDAY/

06/00Z TAF Discussion: Prevailing VFR conditions will start the 00Z TAF period with mostly clear skies and light winds. Focus overnight turns to fog and stratus potential. Guidance remains somewhat mixed; however, a warm, moist boundary layer favors at least shallow ground fog across the terminals. Maintained MVFR at KCHS and KJZI late tonight/early Friday. Kept KSAV VFR for now, as the highest probability for fog and stratus looks to remain inland.

Trends between the time of morning fog dissipation and the passage of a cold front remain tricky and is a low confidence forecast. Trapped moisture could hold MVFR (or IFR) ceilings into the midday hours until pre-frontal mixing increases. Attention then shifts to the approaching front and a rather quick-moving, broken line of scattered showers Friday afternoon. Isolated thunder cannot be completely ruled out, but probabilities remain too low to justify a TSRA mention at this time. Introduced a PROB30 to mention -SHRA given timing and coverage uncertainties.

Extended Aviation Outlook: It's possible to see some brief flight restrictions as scattered showers and thunderstorms pass through the region on Friday afternoon/evening.

MARINE

Through tonight: The local waters will sit ahead of an approaching cold front. This setup will favor modest southerly flow with wind speeds mostly topping out around 10 knots. Seas will continue to average 2-4 feet, highest beyond 20 nm.

Friday through Tuesday: A weak cold front will push offshore across the waters on Friday evening, however no significant marine conditions are expected except for a wind shift to the north- northeast on Saturday. Expect wind speeds to range generally from 10 to 15 kts with gusts up to 20 kts possible through the forecast period. Seas will range from 2 to 4ft.

CLIMATE

Record High Temperatures:

November 6: KCXM: 81/2003

CHS WATCHES/WARNINGS/ADVISORIES

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