448
FXUS62 KCAE 171743
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
1243 PM EST FRI JAN 17 2025
SYNOPSIS
MOISTURE INCREASES TONIGHT AND WIDESPREAD SHOWERS EXPECTED
SATURDAY AS A LOW PRESSURE SYSTEM MOVES INTO THE EASTERN U.S.
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. BY THE MIDDLE OF NEXT
WEEK, A COASTAL LOW WILL LIKELY INCREASE PRECIPITATION CHANCES
WITH SOME WINTRY POTENTIAL POSSIBLE BUT STILL UNCERTAIN.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGE(S):
- QUIET, SUNNY DAY WITH NEAR NORMAL TEMPS
- CLOUDS INCREASE TONIGHT, WITH RAIN CHANCES INCREASING NEAR
DAWN
TRANSIENT HIGH PRESSURE IS FORECAST TO CONTINUE SHIFTING
EASTWARD THROUGH THE FORECAST AREA TODAY. SHORTWAVE RIDGING IS
EXPECTED TO ACCOMPANY THE SURFACE HIGH PASSING THROUGH THE
REGION TODAY, WITH CONVERGENCE AND LOW PWS LEADING TO MOSTLY
SUNNY SKIES ACROSS THE AREA. SURFACE WINDS ARE LIKELY TO SHIFT
OUT OF THE SOUTHEAST BY THIS AFTERNOON, BUT TEMPERATURE
ADVECTIONS ARE EXPECTED TO REMAIN AT A MINIMUM. HIGHS WILL BE
SIMILAR TO YESTERDAY'S AS A RESULT, WITH TEMPS GETTING INTO THE
MID AND UPPER 50S. ALL I HAVE TO SAY IS ENJOY IT! OUR LONG TERM
TEMP OUTLOOK IS WAY COLDER THAN THAT. CLOUDS AND MOISTURE WILL
BEGIN TO INCREASE OVERNIGHT AS SOUTHWESTERN US SHORTWAVE TROUGH
BEGINS TO EJECT AND APPROACH THE SOUTHEASTERN US. THIS SHOULD
OVERSPREAD BROAD UPPER LEVEL LIFT OVER THE AREA AFTER 09Z BUT
PWS ARE STILL EXPECTED TO REMAIN BELOW 1" UNTIL AFTER 12Z. SO
WHILE RAIN IS MOST LIKELY AFTER 12Z, SOME MAY OCCUR AS LIFT
INCREASES BEFORE THEN. ANY RAINFALL WILL LIKELY BE LIGHT,
THOUGH. TEMPS WILL LIKELY HAVE A NON-DIURNAL CURVE TONIGHT,
FALLING TO LOW POINTS BEFORE 06Z AND THEN SLOWLY RISING AS
CLOUDS INCREASE AND WE MOVE MORE INTO THE SPHERE OF INFLUENCE OF
THE NEXT APPROACHING LOW PRESSURE SYSTEM.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
KEY MESSAGE(S):
- DRY HIGH PRESSURE IN PLACE TODAY WITH SEASONABLE TEMPERATURES.
- SHOWERS MOVE IN SATURDAY AHEAD OF A STRONG FRONT.
UPPER LEVEL TROUGH AND COLD FRONT MOVING INTO THE SOUTHEASTERN
CONUS DURING THE PERIOD. SOUTH- WESTERLY LOW-LEVEL DEVELOPS
EARLY WITH 850MB WINDS 30-40 KTS. THE MOISTURE TRANSPORT APPEARS
FOCUSED IN THE SOUTHEAST MIDLANDS DURING THE MORNING WITH
PRECIPITABLE WATER INCREASING TO AROUND 1 INCH. LOWER
PRECIPITABLE WATER IN THE WEST MIDLANDS AND PIEDMONT. FORCING
AHEAD OF THE SHORT WAVE TROUGH APPEARS STRONG THOUGH WITH AREA
IN LEFT FRONT EXIT REGION OF 250MB JET MAX EAST-WEST OVER THE
GULF COAST REGION. EXPECT RELATIVELY STRONG UPPER LEVEL
DIVERGENCE. THE ISENTROPIC LIFT APPEARS STRONGER IN THE COASTAL
PLAIN. THE CAM MODELS SUPPORT HIGHER POPS IN THE MORNING, WHILE
THE MOS GUIDANCE HAS DECREASED A BIT. OVERALL QPF NOT HIGH,
PERHAPS 0.25-0.5 INCH. EXPECT THE BULK OF THE PRECIPITATION IN
THE MORNING, BECOMING SCATTERED IN THE AFTERNOON AS A WEAK
SURFACE LOW MOVES TO THE NORTHEAST OFFSHORE. FRONTAL BOUNDARY
LIKELY STILL NEAR THE AREA AND CONTINUED SOUTH-WESTERLY FLOW
SHOULD CONTINUE TO TRANSPORT MOISTURE INTO THE AREA THROUGH THE
DAY. THE FRONTAL BOUNDARY STALLS NEAR THE AREA. TEMPERATURES
REMAIN SEASONABLE. ADDITIONAL SHORT WAVES AND THE WEAK SURFACE
LOW ON THE FRONT MAY PROVIDE ADDITIONAL SCATTERED SHOWERS IN THE
EVENING THROUGH SUNDAY MORNING BUT SCATTERED COVERAGE EXPECTED.
THE FRONT SHOULD BE EAST OF THE AREA BY SUNDAY AFTERNOON AND
WITH COLD ADVECTION DEVELOPING, BREEZY CONDITIONS EXPECTED.
LONG TERM /MONDAY THROUGH FRIDAY/
KEY MESSAGE(S):
- TEMPS 15-25 DEGREES BELOW AVERAGE EXPECTED MONDAY THROUGH THURSDAY.
- WINTRY PRECIP CHANCES CONTINUE FOR MID-WEEK, BUT CONFIDENCE
REMAINS LOW.
STRONG COLD ADVECTION SUNDAY NIGHT WITH 850MB TEMPERATURES
FALLING TO BELOW -10C BY MIDNIGHT. VERY BROAD AND AMPLIFIED
UPPER TROUGH OVER THE CONUS WILL DRIVE AN ARCTIC AIR MASS INTO
THE SOUTHEASTERN U.S. MODELS INDICATING A VERY STRONG HIGH
PRESSURE AREA 1040MB WILL SETTLE OVER THE MID ATLANTIC GIVEN THE
STRONG UPPER LEVEL CONVERGENCE IN THAT REGION AND BUILD SOUTH
INTO THE CAROLINAS AND GEORGIA EARLY IN THE WEEK. THIS AIR MASS
WILL BE UNUSUALLY COLD FOR SC/GA. THE AIR MASS IS HIGHLY
ANOMALOUSLY COLD BUT NOT RECORD SETTING. LOOKING AT TEMPS 15-25
DEGREES BELOW NORMAL, SO HIGHS IN THE 30S AND LOWS IN THE TEENS
TO LOW 20S. EC EFI CONTINUES TO SHOW EFI VALUES BETWEEN 0.9 AND
0.95 MONDAY AND TUESDAY, BUT SOT IS VERY LOW; A CLASSIC HIGH
CONFIDENCE IN WELL BELOW AVERAGE, BUT NOT EXTREME TEMPS, SIGNAL.
REGARDLESS, THE LREF OUTPUT SUGGESTS WE WILL APPROACH OR EXCEED
COLD WEATHER ADVISORY CRITERIA AT SOME POINT NEXT WEEK, SO STAY
AWARE OF THAT POTENTIAL NEW PRODUCT ISSUANCE. FROZEN PIPES AND
RELATED IMPACTS ARE BECOMING MORE LIKELY DURING THE MID- WEEK
PERIOD AS HIGH TEMPS WILL ONLY MAKE IT ABOVE FREEZING FOR A FEW
HOURS EACH DAY.
AN UPPER TROUGH IS EXPECTED TO MOVE FROM THE DESERT SOUTHWEST
ACROSS THE GULF COAST REGION TUESDAY AND INITIATE LOW PRESSURE
IN THE GULF OF MEXICO AND TRACK EAST ACROSS FLORIDA TO POSSIBLY
NEAR THE SC COAST. THE REMAINS QUITE UNCERTAINTY HOW FAST THE
THE TROUGH WILL MOVE EAST AND POSSIBLY PHASE WITH THE NORTHERN
STREAM DIGGING TROUGH INTO THE MID MISSISSIPPI VALLEY. THE GFS
CONTINUES TO BE FASTER MOVING THE SHORT WAVE EAST FROM THE
DESERT SOUTHWEST AND DOES NOT PHASE WITH THE NORTHERN STREAM
TROUGH. THIS LEADS TO THE MOISTURE SUPPRESSED FURTHER TO THE
SOUTH. SNOW PROBABILITIES REMAIN HIGHEST IN THE SOUTHERN PORTION
OF THE AREA TUESDAY/TUESDAY NIGHT. THE CANADIAN REMAINS THE
MOST AGGRESSIVE WITH WINTER WEATHER POTENTIAL. THE ECMWF/UKMET
ARE COMPROMISES. ONE CONCERN WITH THE LATEST 00Z 1/17 GUIDANCE,
THE GFS HAS TRENDED BACK INLAND A BIT WITH THE SNOWFALL. WILL
OBVIOUSLY CONTINUE TO MONITOR THIS WINTRY POTENTIAL.
AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
VFR CONDITIONS THROUGH THE TAF PERIOD.
HIGH PRESSURE MOVES EAST THIS AFTERNOON, WITH A COLD FRONT
APPROACHING FROM THE WEST LATE THIS WEEKEND. THE NEXT 24 HOURS
WILL REMAIN MOSTLY VFR, ALTHOUGH CLOUDS WILL BE ON THE INCREASE
LATER TONIGHT. MOSTLY CLEAR SKIES THROUGH THIS AFTERNOON, THEN
BROKEN TO OVERCAST UPPER TO MID LEVEL CLOUDINESS MOVES IN AFTER
SUNSET. VFR CEILINGS WILL HOWEVER CONTINUE OVERNIGHT AND INTO
SATURDAY MORNING. RAINFALL SHOULD BE MOVING INTO THE CSRA SITES
BY SUNRISE, THEN INTO THE MIDLANDS BETWEEN 13Z-15Z. VISIBILITIES
IN THE RAIN EXPECTED TO DROP TO MVFR THROUGH THE DAY AT ALL
SITES. NEAR THE END OF THE 24 HOUR FORECAST PERIOD, CONFIDENCE
INCREASING FOR IFR CEILINGS, ESPECIALLY AT AGS/DNL, SO HAVE
INTRODUCED THOSE CONDITIONS ACROSS THE CSRA BY 16Z SATURDAY.
WINDS LIGHT AND OUT OF THE EAST THIS AFTERNOON, THEN MOSTLY
LIGHT AND VARIABLE FROM SUNSET ONWARD INTO SATURDAY. WINDS MAY
BECOME MORE SOUTHERLY LATE IN THE PERIOD AS THE SYSTEM MOVES
THROUGH.
EXTENDED AVIATION OUTLOOK
RESTRICTIONS ARE EXPECTED ON
SATURDAY AFTERNOON AS A LOW PRESSURE SYSTEM WORKS ITS WAY
THROUGH THE REGION.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
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