Area Forecast Discussion
Issued by NWS Columbia, SC

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000 FXUS62 KCAE 010249 AFDCAE AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 1049 PM EDT FRI OCT 31 2014 .SYNOPSIS... A STRONG UPPER LEVEL LOW WILL CONTINUE PUSHING TOWARDS THE REGION OVERNIGHT...HELPING TO PUSH A COLD FRONT THROUGH THE FORECAST AREA. BEHIND THIS FRONT...MUCH COLDER AIR WILL FOLLOW ALONG WITH BREEZY CONDITIONS. THE FIRST WIDESPREAD FROST ALONG WITH THE FIRST FREEZE OF THE SEASON FOR SOME AREAS WILL LIKELY OCCUR SUNDAY NIGHT/MONDAY MORNING. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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UPDATE...BASED ON LATEST OBSERVATIONS UPSTREAM GUSTY WINDS EXPECTED ON AREA LAKES OVERNIGHT..ESPECIALLY CLARKS HILL. LAKE WIND ADVISORY IN EFFECT AT 4AM... AS OF 02Z...REGIONAL RADAR LOOP SHOWING MOST OF THE SHOWERS AND THUNDERSTORMS ALONG AND AHEAD OF THE FRONT HAVE SHIFTED INTO THE EASTERN HALF OF THE FORECAST AREA. HAVE RECEIVED REPORTS OF SOME SMALL HAIL ASSOCIATED WITH THESE STORMS WHICH IS NOT SURPRISING DUE TO THE RELATIVELY LOW FREEZING LEVEL AND WEAK INSTABILITY. STORMS WILL TAPER OFF WITHIN THE NEXT COUPLE OF HOURS WITH MAINLY RAIN SHOWERS THROUGH THE OVERNIGHT PERIOD. THE DEEP UPPER LEVEL CUT OFF LOW WILL CONTINUE DIGGING TOWARD THE CSRA OVERNIGHT. SURFACE ANALYSIS SHOWS THE COLD FRONT CURRENTLY STRETCHED ACROSS THE UPSTATE OF SOUTH CAROLINA. THE FRONTAL BOUNDARY WILL SHIFT EAST ACROSS THE FORECAST AREA TONIGHT. THE HIGHEST RAIN CHANCES WILL BE IN THE NORTHERN MIDLANDS AND PEE DEE REGIONS DURING THE OVERNIGHT PERIOD WHERE THE BEST MOISTURE IS LOCATED. WINDS HAVE ALREADY PICKED UP ACROSS THE AREA TONIGHT AND WILL CONTINUE TO INCREASE TOWARD SATURDAY MORNING AS THE PRESSURE GRADIENT TIGHTENS AND COLD AIR ADVECTION INCREASES. OVERNIGHT LOWS IN THE UPPER 30S WEST TO LOWER 40S EAST.
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&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
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THE CLOSED OFF UPPER LOW WILL CONTINUE TO MOVE EAST INTO THE UPPER SAVANNAH RIVER VALLEY BY SATURDAY MORNING...THEN RAPIDLY MOVE TOWARDS THE COAST BY EARLY SATURDAY AFTERNOON. HAVE GONE WITH LIKELY POPS ON SATURDAY ACROSS THE NORTHERN MIDLANDS WITH A GRADUAL TAPER IN POPS SOUTHWARD THROUGH THE PERIOD. SIGNIFICANT COLD POOL ALOFT WITH THIS SYSTEM...AND THUS WITH SUCH COLD TEMPERATURES ALOFT...WOULD NOT BE SURPRISED TO SEE A FEW REPORTS OF FROZEN PRECIPITATION MIXED IN WITH THE LIGHT RAIN EARLY SATURDAY. HAVE INTRODUCED RAIN MIXED WITH SNOW IN THE FAR WESTERN MIDLANDS AND CSRA DURING THE 10Z TO 14Z TIME FRAME. BELIEVE THIS AREA MAY HAVE THE BEST CHANCE TO SEE A MIX DUE TO THE COOLER TEMPERATURES WRAPPING AROUND THE LOW IN THIS AREA AND THE BETTER MOISTURE. 850 TEMPS ARE EXTREMELY IMPRESSIVE AT -5 TO -6 IN PARTS OF THE CSRA. THE 18Z NAM HAS MOISTURE AND UPWARD VERTICAL MOTION IN THE SNOW GROWTH REGION...WHILE THE GFS IS MORE MARGINAL. ALSO CAN NOT RULE OUT SHALLOW CONVECTION WITH THE STRENGTH OF THE LOW...WHICH COULD ALSO BRING SOME GRAUPEL TO THE AREA. NO ACCUMS...AND CONFIDENCE NOT HIGH. EXPECT RAIN TO BE THE MAIN PRECIPITATION TYPE THROUGH THE EVENT. TEMPERATURES ON SATURDAY WILL BE SIGNIFICANTLY COLDER...NEARLY 15-20 DEGREES COLDER THAN RECENT DAYS...WITH HIGHS STRUGGLING TO REACH 50 DEGREES IN THE MIDLANDS. MAX TEMPERATURES WILL RANGE FROM THE MID TO UPPER 40S ACROSS MUCH OF THE NORTHERN MIDLANDS...THE POSSIBLY THE LOWER 50S IN THE CSRA. THE OTHER FORECAST ISSUE TO DEAL WITH DURING THIS PERIOD WILL BE THE INCREASING SURFACE GRADIENT AND THE STRONG 40 TO 50 KNOT LOW LEVEL JET MOVING ACROSS THE REGION SATURDAY AFTERNOON AND EVENING. THE STRONGEST WINDS WILL DEVELOP ACROSS THE CWA ON SATURDAY AND CONTINUE SATURDAY EVENING WITH A GRADUAL DECREASE TOWARD SUNDAY MORNING. WITH THE LAKE WATER TEMPERATURES IN THE UPPER 60S TO AROUND 70 DEGREES AND STRONG COLD AIR ADVECTION...EXPECT WINDS TO REMAIN RATHER BREEZY ACROSS THE LAKES FROM SATURDAY MORNING TO SUNDAY MORNING. WILL CONTINUE WITH THE CURRENT LAKE WIND ADVISORY WHICH RUNS FROM 10 AM EDT SATURDAY UNTIL 10 AM EST SUNDAY. SUSTAINED WINDS 15 TO 25 MPH WITH GUSTS AS HIGH AS 30 TO 40 MPH EXPECTED ON SATURDAY/SATURDAY EVENING. AS THE UPPER LOW MOVES OFFSHORE BY SATURDAY EVENING...HIGH PRESSURE ASSOCIATED WITH A COLD DRY CANADIAN AIRMASS WILL SETTLE OVER THE AREA FOR THE REMAINDER OF THE WEEKEND. A STRONG PRESSURE GRADIENT WILL PERSIST THROUGH THE OVERNIGHT HOURS SATURDAY NIGHT WHICH WILL PREVENT IDEAL STRONG RADIATIONAL COOLING FROM OCCURRING BY KEEPING MUCH OF THE BOUNDARY LAYER WELL MIXED. THIS MEANS THAT LOWS SATURDAY NIGHT AND SUNDAY MORNING WILL GENERALLY BE DETERMINED BY THE COLD ADVECTION TAKING PLACE INSTEAD OF BY RADIATIONAL COOLING. THIS PUTS LOWS GENERALLY IN THE MID 30S. SUNDAY WILL FEATURE DECREASING CLOUDINESS AND MOSTLY SUNNY SKIES WITH SLIGHTLY WARMER BUT STILL WELL BELOW NORMAL TEMPERATURES WITH HIGHS IN THE 50S. THE BEST NIGHT FOR WIDESPREAD FROST AND THE POTENTIAL FOR FREEZING TEMPERATURES APPEARS TO BE LATE SUNDAY NIGHT AND MONDAY MORNING. WINDS SHOULD DIMINISH UNDER LOW-LEVEL INVERSION...SKIES WILL BE CLEAR...AND AIRMASS WILL BE DRY. THIS CREATES IDEAL RADIATIONAL COOLING CONDITIONS. OVERNIGHT LOWS WILL FALL INTO THE LOWER TO MID 30S...WITH UPPER 20S REMAINING POSSIBLE IN THE TYPICAL COLD SPOTS. SOME OF THE NUMBERS FOR BUSH FIELD STILL TRY TO TAKE THE TEMPERATURE DOWN INTO THE MID/UPPER 20S...WHICH IS QUITE IMPRESSIVE AND SEASONABLY COLD FOR EARLY NOVEMBER. FOR SUNDAY NIGHT...AT A MINIMUM WILL LIKELY NEED A FROST ADVISORY...BUT IF GUIDANCE CONTINUES THE DOWNWARD TREND...AND IT CONTINUES TO SHOW IDEAL RADIATIONAL CONDITIONS...A FREEZE WARNING MAN BE NEEDED INSTEAD FOR PORTIONS OF THE CWA. THESE WOULD BE ISSUED WITH LATER PACKAGES IF NEEDED.
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&& .LONG TERM /MONDAY THROUGH FRIDAY/... BEHIND THIS SYSTEM...COOL AND DRY WEATHER SHOULD PERSIST AT LEAST INTO WEDNESDAY. MONDAY MORNING TEMPERATURES WILL START OFF WELL BELOW NORMAL IN THE LOWER TO MID 30S...WITH WIDESPREAD FROST EXPECTED ALONG WITH SOME AREAS OF FREEZING/BELOW FREEZING TEMPERATURES. FULL SUNSHINE EXPECTED WITH A DRY AIRMASS IN PLACE WILL YIELD SLIGHTLY WARMER TEMPERATURES COMPARED TO SUNDAY BUT STILL REMAINING WELL BELOW NORMAL. THE SURFACE RIDGE WILL SHIFT OFFSHORE ON TUESDAY WITH A RETURN SOUTHERLY FLOW EXPECTED AROUND THE SURFACE HIGH...WHICH WILL PROVIDE WARMER TEMPERATURES AND INCREASED LOW LEVEL MOISTURE. NEAR NORMAL TEMPERATURES EXPECTED TUESDAY WITH HIGHS IN THE UPPER 60S TO LOWER 70S AND MUCH WARMER MIN TEMPERATURES TUESDAY NIGHT IN THE UPPER 40S. THE FORECAST BECOMES A BIT MORE CHALLENGING AND LESS CONFIDENT BY MID WEEK...DUE TO TIMING AND STRENGTH ISSUES. WILL CARRY SLIGHT CHANCE POPS WED NGT/THU WITH APPROACHING FRONT. TEMPERATURES WILL WARM BACK TO NEAR OR SLIGHTLY ABOVE NORMAL VALUES. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... A COLD FRONT WILL MOVE THROUGH THE AREA TONIGHT. SCATTERED SHOWERS HAVE FORMED AHEAD OF THE COLD FRONT AND WILL BE IN THE VICINITY OF ORANGEBURG FOR THE NEXT FEW HOURS. NORTHWESTERLY WINDS WILL BEGIN TO STRENGTHEN AS THE FRONT PASSES BRINGING LOWERED CEILINGS AND THE POSSIBILITY OF SHOWERS AFTER 09Z. ON SATURDAY... THE BEST CHANCE FOR WIDESPREAD SHOWERS REMAINS IN THE PEE DEE AND NORTHERN MIDLANDS. CONFIDENCE HAS INCREASED TO ADD -SHRA AFTER 15Z FOR THE COLUMBIA AIRPORTS. NORTHWEST SURFACE WINDS NEAR 15 KNOTS WITH GUSTS UP TO 30 KNOTS ARE LIKELY THROUGHOUT THE DAY WITH THE STRONGEST WINDS EXPECTED IN THE LATE AFTERNOON. .EXTENDED AVIATION OUTLOOK... BREEZY CONDITIONS EXPECTED TO CONTINUE INTO SUNDAY MORNING WHICH WILL INHIBIT FOG AND FROST FORMATION FOR SUNDAY MORNING. DRY AIR BEHIND THE FRONT WILL ALLOW FOR CLEAR SKIES INTO MONDAY. THERE IS A POSSIBILITY FOR FROST MONDAY MORNING AS TEMPERATURES DROP NEAR FREEZING WITH LIGHT WINDS. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...LAKE WIND ADVISORY FROM 4 AM EDT SATURDAY TO 10 AM EST SUNDAY FOR SCZ015-016-018-020>022-025>031-035>038-041. GA...LAKE WIND ADVISORY FROM 4 AM EDT SATURDAY TO 10 AM EST SUNDAY FOR GAZ040-063>065-077. && $$

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