Area Forecast Discussion
Issued by NWS Columbia, SC

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151
FXUS62 KCAE 041817
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
217 PM EDT WED MAY 4 2016

.SYNOPSIS...
COLD FRONT CONTINUES DEPARTING THE REGION ALLOWING A COOLER AND
DRIER AIRMASS TO OVERSPREAD THE AREA. A REINFORCING COLD FRONT
WILL CROSS THE AREA TONIGHT WITH MUCH COOLER TEMPERATURES ALONG
WITH A CHANCE OF SHOWERS FOR THURSDAY AND FRIDAY. DRY CONDITIONS
AND A WARMING TREND WILL DOMINATE THE AREA FOR THE WEEKEND INTO
EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
DIURNAL CUMULUS WILL REMAIN ACROSS THE FORECAST AREA THROUGH THIS
AFTERNOON THEN DISSIPATE WITH SUNSET AND LOSS OF HEATING.
OVERNIGHT SURFACE AND UPPER LEVEL TROUGHS WILL MOVE THROUGH THE
REGION ALLOWING ADDITIONAL COOLER AIR INTO THE REGION. INCREASING
CLOUDS WILL BE ASSOCIATED WITH THESE FEATURES...HOWEVER NO RAIN IS
EXPECTED. THE CLOUDS AND WINDS BETWEEN 5 TO 10 MPH OVERNIGHT WILL
PREVENT RADIATIONAL COOLING FROM BECOMING OPTIMAL RESULTING IN
OVERNIGHT LOWS IN THE LOWER TO MIDDLE 50S.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
CLOSED UPPER LOW WILL DROP SOUTH OVER THE CAROLINAS ON THURSDAY WITH
A SIGNIFICANT COLD POOL ALOFT WITH 500MB TEMPS AROUND -25C.  SURFACE
LOW PRESSURE OVER EASTERN NORTH CAROLINA WILL SHIFT OFFSHORE WHILE
PREDOMINANT SURFACE AND LOW LEVEL FLOW OVER THE FORECAST AREA WILL
BE FROM THE NORTHWEST.  0-3KM LAPSE RATES EXPECTED TO BECOME VERY
STEEP BY LATE MORNING THROUGH THE AFTERNOON AROUND 8-9 C/KM WITH
LIFTED INDEX VALUES FALLING TO AROUND -2C.  WHILE PRECIPITABLE WATER
VALUES WILL BE MARGINAL AROUND 0.5 TO 0.6 INCHES...IT SHOULD BE
SUFFICIENT ALONG WITH THE INSTABILITY TO PROVIDE DIURNAL CONVECTIVE
SHOWERS AND MAYBE ISOLATED THUNDERSTORMS.  CANNOT RULE OUT THE
POSSIBILITY OF A FEW SMALL HAIL OR GRAUPEL REPORTS DUE TO THE
SIGNIFICANT COLD POOL ALOFT AND STRONGER WIND GUSTS WITH EVAPORATIVE
COOLING THAT WILL TAKE PLACE WITH DRY AIR ALOFT AND A BIT OF AN
INVERTED-V SOUNDING NEAR THE SURFACE. HAVE INCREASED THE POPS A
BIT ACROSS THE NORTHERN MIDLANDS TO SOLID CHANCE POPS AND TAKE THE
SLIGHT CHANCE POPS INTO THE CSRA.

SHOWERS SHOULD WANE DURING THE EVENING HOURS AS THE ATMOSPHERE
RESTABILIZES WITH THE LOSS OF HEATING BUT COULD SEE SOME LINGERING
SHOWERS ACROSS THE NORTHERN MIDLANDS CLOSER TO THE CENTER OF THE
UPPER LOW AND BETTER FORCING.  THE UPPER LOW WILL LIFT INTO EASTERN
NC/VA THURSDAY NIGHT AND BECOME NEARLY STATIONARY AS MORE SHORTWAVE
ENERGY DIVES DOWN THE BACK SIDE OF THE UPPER LOW FOR FRIDAY WHICH
WILL WARRANT KEEPING SOME POPS ACROSS THE PEE DEE REGION AND
MIDLANDS NORTH OF A LINE FROM NEWBERRY TO COLUMBIA TO LAKE MARION.
THE UPPER LOW WILL PULL AWAY FROM THE REGION FRIDAY NIGHT AS SKIES
CLEAR WITH NO PRECIPITATION EXPECTED.

TEMPERATURES WILL BE WELL BELOW NORMAL THIS PERIOD WITH HIGHS
STRUGGLING TO GET INTO THE 70S ON THURSDAY DUE TO CLOUD COVER AND
COOL AIR MASS AND SHOWERS ASSOCIATED WITH THE UPPER LOW.  SLIGHTLY
WARMER TEMPERATURES EXPECTED ON FRIDAY WITH HIGHS IN THE LOWER TO
MID 70S.  LOWS THURSDAY NIGHT WILL BE IN THE UPPER 40S AND FURTHER
COOLING LIMITED BY A MIXED BOUNDARY LAYER FOLLOWED BY SLIGHTLY
WARMER TEMPERATURES FRIDAY NIGHT IN THE LOWER 50S.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
NOT TOO MUCH CHANGE IN THE FORECAST THIS PERIOD FROM PREVIOUS
FORECAST AS PATTERN TRANSITIONS A BIT WITH THE CLOSED UPPER LOW
OPENING UP AND LIFTING AWAY FROM THE MID-ATLANTIC AS ANOTHER
SHORTWAVE MOVES ACROSS THE NORTHEAST AND UPPER FLOW BECOMES MORE
ZONAL OVER THE FORECAST AREA.

NORTHWEST TO WESTERLY DOWNSLOPING MID LEVEL FLOW TRANSITIONS TO MORE
WESTERLY FLOW AND A DEVELOPING SOUTHERLY SURFACE FLOW WILL ALLOW FOR
MODERATING TEMPERATURES OVER THE WEEKEND WITH TEMPS RISING BACK
ABOVE NORMAL IN THE UPPER 80S TO AROUND 90 EARLY NEXT WEEK. SOME
GENERAL AGREEMENT AMONG THE MEDIUM RANGE MODELS SHOW UPPER RIDGING
OVER THE SOUTHEASTERN STATES WHILE A DEEP CLOSED LOW SLOWLY DRIFTS
EASTWARD OUT OF THE INTERMOUNTAIN WEST.  THIS WILL SET UP A SERIES
OF SHORTWAVES MOVING THROUGH THE SOUTHWESTERLY FLOW TO TRACK OUT OF
THE MISSISSIPPI VALLEY NORTHEASTWARD TOWARDS THE FORECAST AREA MID
WEEK. THERE REMAINS SOME DIFFERENCES AMONG THE MODELS REGARDING
MOISTURE AVAILABLE AND HOW THAT MAY RESULT IN PRECIPITATION FOR OUR
AREA SO WILL CONTINUE A DRY FORECAST THROUGH TUESDAY AND INTRODUCE
SLIGHT CHANCE POPS ON WEDNESDAY.

TEMPERATURES THROUGH THIS PERIOD WILL BE SLIGHTLY BELOW TO NEAR
NORMAL ON SATURDAY WITH HIGHS IN THE LOWER 80S BUT THEN WARM ABOVE
NORMAL SUNDAY THROUGH WEDNESDAY WITH HIGHS IN THE UPPER 80S TO
AROUND 90 DEGREES.  LOWS WILL GENERALLY BE IN THE 60S.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
VFR CONDITIONS THROUGH THE PERIOD.

COLD FRONT CONTINUES MOVING AWAY FROM THE REGION WITH DIURNAL
CUMULUS DEVELOPING ACROSS THE TAF SITES. EXPECT THE CUMULUS AND
WIND GUSTS UP TO 18 KNOTS TO LINGER INTO THIS EVENING THEN
DIMINISH WITH SUNSET. OVERNIGHT UPPER LEVEL AND SURFACE TROUGHS
WILL CROSS THE AREA ALLOWING ADDITIONAL COOLER AIR TO MOVE INTO
THE AREA. THIS WILL RESULT IN CLOUDS INCREASING AS THE TROUGHS
CROSS THE TAF SITES...HOWEVER NO SHOWERS ARE EXPECTED. VERY LATE
IN THE TAF PERIOD AN UPPER LEVEL LOW WILL MOVE INTO THE AREA ALONG
WITH SCATTERED DIURNAL SHOWERS. CONFIDENCE IN TIMING OF SHOWERS
REMAINS LOW SO HAVE NOT INCLUDED MENTION WITH THIS TAF ISSUANCE.

EXTENDED AVIATION OUTLOOK...FLIGHT RESTRICTIONS POSSIBLE IN ISOLATED
TO SCATTERED SHOWERS/THUNDERSTORMS THURSDAY AFTERNOON INTO THURSDAY
NIGHT.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.

&&

$$
SYNOPSIS...MP
NEAR TERM...HC
SHORT TERM...HC
LONG TERM...HC
AVIATION...MP



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