176
FXUS62 KCAE 150919
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
419 AM EST WED JAN 15 2025
SYNOPSIS
DRY CONDITIONS ARE EXPECTED THROUGH THE END OF THE WEEK, THEN
SHOWERS LIKELY THIS WEEKEND AS A LOW PRESSURE SYSTEM CROSSES
INTO THE EASTERN US. BEHIND THE SYSTEM, EXPECT WELL BELOW
NORMAL TEMPERATURES AS A ANOMALOUSLY DEEP TROUGH AND SURFACE
HIGH PUSHES AN ARCTIC AIR MASS INTO THE CENTRAL AND EASTERN US.
MOISTURE MAY RETURN TO THE FORECAST NEAR THE END OF THE LONG
TERM SUPPORTING A SLIGHT CHANCE OF PRECIPITATION.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGE(S):
- DRY HIGH PRESSURE WILL BUILD INTO THE REGION THROUGH TONIGHT
SATELLITE IMAGERY SHOWS SOME HIGH CLOUDS MOVING ACROSS THE
SOUTHEAST THIS MORNING. A COLD FRONT MOVING THROUGH NORTH
CAROLINA THIS MORNING WILL ARRIVE IN THE AREA AROUND SUNRISE,
DRIVEN BY A SHORTWAVE THAT WILL BE MOVING OFF THE MID- ATLANTIC
COAST.
BEHIND THIS SHORTWAVE, WINDS WILL SHIFT FROM WEST TO NORTH AND
DEWPOINTS WILL FALL INTO THE SINGLE DIGITS NORTH TO 20S SOUTH.
THE LOW LEVEL JET THIS MORNING WILL PRODUCE A BRIEF PERIOD OF
WIND GUSTS FROM 10 TO 15 MPH, BUT TAPER BY MIDDAY. EXPECT DRY
AND COOL WITH TEMPERATURES BELOW NORMAL. HIGHS WILL RANGE FROM
THE MIDDLE 40S NORTH TO LOWER TO MIDDLE 50S FAR SOUTH.
EXPECT A FEW HIGH CLOUDS TONIGHT, BUT WINDS SHOULD REMAIN RATHER
LIGHT. THIS WILL ALLOW TEMPERATURES TO DROP OFF NICELY ACROSS
THE CWA. EXPECT LOWS IN THE LOWER TO MIDDLE 20S NORTH/CENTRAL TO
NEAR 30 ACROSS THE CSRA.
SHORT TERM /THURSDAY/
KEY MESSAGE(S):
- COOL, DRY WEATHER CONTINUES. BREEZY THURSDAY.
AN UPPER LEVEL TROUGH WILL DIG INTO THE EASTERN US ON THURSDAY
WITH HIGH PRESSURE PUSHING OFFSHORE ON FRIDAY. PWAT VALUES FROM
THURSDAY TO 00Z ON FRIDAY WILL RANGE FROM 0.2 TO 0.4 INCHES
INDICATING CONTINUED DRY WEATHER. TEMPERATURES SHOULD BE WARMER
ON THURSDAY THAN THE PREVIOUS DAY AS THE AIR MASS MODIFIES.
EXPECT HIGHS IN THE MID TO UPPER 50S. A TIGHT PRESSURE GRADIENT
WILL ALLOW FOR BREEZY WINDS ON THURSDAY WITH GUSTS TO 25 MPH,
SUBSIDING OVERNIGHT AS HIGH PRESSURE MOVES OVER THE AREA. LOWS
ON THURSDAY NIGHT WILL RANGE FROM MID 20S TO AROUND FREEZING. ON
FRIDAY, THE CENTER OF THE SURFACE HIGH WILL SHIFT OFFSHORE
PROMOTING INCREASING SOUTHERLY FLOW ACROSS THE SOUTHEAST THROUGH
THE DAY. EXPECT HIGHS IN THE 50S. MOISTURE ADVECTION REMAINS
WEAK DURING THE DAYLIGHT HOURS SO WE EXPECT RAINFALL TO HOLD OFF
UNTIL OVERNIGHT.
LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/
KEY MESSAGE(S):
- WIDESPREAD RAIN FRIDAY NIGHT AND SATURDAY, THUNDERSTORMS UNLIKELY
- WELL BELOW NORMAL TEMPERATURES RETURN FOR SUN NIGHT AND NEXT WEEK
- MOISTURE SPREADS INTO THE SOUTHEAST NEAR THE END OF THE PERIOD
REX BLOCKING CURRENTLY OVER THE WEST COAST WILL BREAK DOWN OVER THE
COURSE OF THIS WEEK. THE CUTOFF LOW WILL EVENTUALLY BE PICKED UP AND
MOVE INTO THE EASTERN US. AT THE SURFACE, THE ASSOCIATED LOW
PRESSURE SYSTEM IS EXPECTED TO LIFT FROM THE SOUTH CENTRAL US INTO
THE SOUTHERN APPALACHIANS. DEEP, SOUTHERLY FLOW DEVELOPS ACROSS THE
FORECAST AREA FRIDAY NIGHT IN RESPONSE TO THE APPROACHING SYSTEM.
PWAT VALUES RISE FROM ONE THIRD OF AN INCH FRIDAY EVENING TO 1-1.3
INCHES BY SATURDAY MORNING. DIVERGENCE ALOFT, CONVERGENCE AHEAD OF
THE FRONT, AND DEEP MOISTURE ALL SUPPORT WIDESPREAD SHOWERS. WEAK
CONDITIONAL INSTABILITY LIMITS THE THREAT OF THUNDERSTORMS. RAINFALL
WILL TAPER OFF LATE SATURDAY AS THE FRONTAL SYSTEM MOVES EAST OF THE
AREA AND DRY, COLD AIR TAKES ITS PLACE.
AN ANOMALOUSLY DEEP 500 MB TROUGH (NEAR THE NAEFS CLIMATOLOGICAL
MINIMUM FOR THIS TIME OF YEAR) WILL DIP INTO THE NORTH CENTRAL US
LATE THIS WEEKEND AND EARLY NEXT WEEK. A STRONG SURFACE HIGH WILL
FILTER ARCTIC AIR INTO THE CENTRAL AND EASTERN US. THERE IS VERY
HIGH CONFIDENCE IN TEMPERATURES WELL BELOW NORMAL. 90 PERCENT OF THE
NBM MEMBERS HAVE HIGH TEMPERATURES IN THE 40S OR LOWER FOR MONDAY
THROUGH WEDNESDAY. MEAN TEMPERATURES HAVE ALSO BEEN TRENDING COLDER
FOR EARLY NEXT WEEK. THERE ARE A GROWING NUMBER OF ENSEMBLE MEMBERS
SHOWING PRECIPITATION OVER THE SOUTHEAST FROM EARLY TO MID NEXT
WEEK. 50 TO 70 PERCENT OF ECMWF MEMBERS AND 30 TO 50 PERCENT OF GEFS
MEMBERS RECORD MEASURABLE PRECIPITATION. THE SYNOPTIC SETUP OF
ABNORMALLY COLD AIR OVER THE REGION AND POTENTIAL FOR MOISTURE TO
SPREAD INTO THE FORECAST AREA IS A SITUATION THAT WILL CONTINUE TO
NEED MONITORING. THAT SAID THERE IS STILL A LARGE SPREAD IN THE
TIMING OF ANY POTENTIAL PRECIP AND AMOUNTS, OR LACK THEREOF. THIS
ULTIMATELY IS KEEPING POPS LIMITED TO SLIGHT CHANCE FOR THE END
OF THE LONG TERM SINCE THE CONFIDENCE OF PRECIP AT ANY GIVEN
PERIOD IS LOW. MODEL GUIDANCE VARIES GREATLY IN THE TRACK OF A
LOW PRESSURE SYSTEM WHICH MAY BRING THE SOUTHEAST SOME FORM OF
WINTRY PRECIP NEAR THE END OF THE LONG TERM.
AVIATION /09Z WEDNESDAY THROUGH SUNDAY/
VFR CONDITIONS CONTINUE....
SATELLITE THIS MORNING CONTINUES TO SHOW SOME HIGH THIN CLOUDS
MOVING ACROSS THE REGION. SURFACE OBSERVATIONS ACROSS GEORGIA
AND THE CAROLINAS INDICATE CEILINGS ARE BETWEEN 15K AND 25K
FEET AND GUIDANCE SUGGESTS THAT FEW TO SCT SKIES WILL CONTINUE
THROUGH MUCH OF THE PERIOD. WEST WINDS FROM 4 TO 8 KNOTS EARLY
THIS MORNING WILL SHIFT TO A NORTHERLY DIRECTION BEHIND A COLD
FRONT BETWEEN 12Z AND 14Z THIS MORNING ALONG WITH A SLIGHT
INCREASE IN WIND SPEEDS THROUGH MIDDAY. WINDS WILL ONCE AGAIN
SLACKEN THIS EVENING AND TONIGHT WITH NEAR CALM WINDS AT MOST
TAF SITES.
EXTENDED AVIATION OUTLOOK...THE NEXT CHANCE FOR SIGNIFICANT
RESTRICTIONS WILL BE LATE FRIDAY AND SATURDAY AS MOISTURE
SPREADS INTO THE SOUTHEAST.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
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