Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 020212
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
1012 PM EDT SUN MAY 1 2016

.SYNOPSIS...
A MOIST SOUTHERLY FLOW WILL CONTINUE INTO THE FORECAST AREA
THROUGH MONDAY AHEAD OF A SLOW MOVING COLD FRONT. THE FRONT WILL
BE NEAR THE REGION TUESDAY AND WEDNESDAY...KEEPING THE CHANCE OF
STORMS IN THE FORECAST.

&&

.NEAR TERM /UNTIL 8 AM MONDAY MORNING/...
SCATTERED STRONG CONVECTION EXPECTED TO CONTINUE ACROSS THE
PIEDMONT AND NORTH MIDLANDS. PWAT AROUND 1.6 INCHES...SO HEAVY
RAIN THREAT CONTINUES.

THERE ARE SOME DIFFERENCES AMONG THE GUIDANCE IN HANDLING
SHORTWAVE ENERGY APPROACHING THE AREA LATER TONIGHT WITH SOME
SHOWING SHOWERS AND THUNDERSTORMS WHILE OTHERS DO NOT. WILL HOLD
ON TO SOME CHANCE POPS TOWARD DAWN MONDAY GIVEN THE POTENTIAL FOR
ADDITIONAL NOCTURNAL CONVECTION. MILD TEMPERATURES ARE EXPECTED
OVERNIGHT IN THE MID TO UPPER 60S AS STRATUS SHOULD REDEVELOP WITH
A STRONG LOW LEVEL JET AND CONTINUED ABUNDANT BOUNDARY LAYER
MOISTURE.

&&

.SHORT TERM /8 AM MONDAY MORNING THROUGH WEDNESDAY/...
.MONDAY...I EXPECT ANOTHER ROUND OF LOW CLOUDS IN THE EARLY
MORNING WITH DECENT WINDS ABOVE THE SURFACE AND A NICE ELEVATED
INVERSION SET UP PER FORECAST SOUNDINGS. DEEP MOISTURE WILL REMAIN
IN PLACE FOR MONDAY AS PW VALUES CONTINUE TO BE IN THE 1.5 TO
1.75 INCH RANGE. SURFACE BOUNDARIES WILL CONTINUE TO BE
RELATIVELY DIFFUSE...BUT ANOTHER IN A SERIES OF WEAK DISTURBANCES
WILL APPROACH FROM THE WEST BY AFTERNOON...HELPING TO SPAWN MORE
SCATTERED SHOWERS AND THUNDERSTORMS. THE BETTER CONCENTRATION OF
CONVECTION IS EXPECTED TO BE IN THE SOUTHEASTERN HALF OF THE CWA
WHERE GREATER LOW LEVEL INSTABILITY WILL RESIDE...BUT THERE IS AT
LEAST A CHANCE EVERYWHERE. MAX TEMPS WILL GET UP INTO THE MID 80S
BEFORE THE CONVECTIVE CLOUD COVER TAKES OVER AND COOLS THINGS
BACK DOWN.

.MONDAY NIGHT...THERE WILL BE ANOTHER GOOD CHANCE OF SHOWERS AND
THUNDERSTORMS MONDAY NIGHT AS THE STRONGEST JET OF THE SERIES
DIPS FURTHER TO THE SOUTHEAST IN RESPONSE TO AN AMPLIFYING TROF
IN EASTERN NORTH AMERICA. THIS CLOSER APPROACH WILL ENHANCE UPPER
LEVEL DIVERGENCE...SUPPORTING CONVECTION DESPITE THE LOSS OF
DAYTIME HEATING. MIN TEMPS WILL AGAIN REMAIN ABOVE NORMAL IN THE
MID TO UPPER 60S DUE TO THICK INSULATING CLOUDS AND SUSTAINED
SOUTHWESTERLY WINDS OF 5 TO 10 KNOTS ALL NIGHT...PROVIDING LOW
LEVEL WARM ADVECTION.

.TUESDAY...RAIN LOOKS LIKELY AGAIN ON TUESDAY AS THE TROF CONTINUES
TO DEEPEN AND A COLD FRONT STARTS TO APPROACH FROM THE
NORTHWEST. DEEP MOISTURE WILL REMAIN IN PLACE OVER THE AREA INTO
EARLY AFTERNOON...BUT SOME DRYING WILL START TOP MOVE IN FROM
THE NORTHWEST LATER IN THE DAY. THE EXACT TIMING IS STILL A
CHALLENGE DUE TO MODEL DIFFERENCES...BUT TO REFLECT THE
UNCERTAINTY I HAVE HIGHER POPS IN THE EASTERN HALF OF THE FA
TUESDAY.

.TUESDAY NIGHT...A COLD FRONT WILL MOVE TROUGH THE CWA TUESDAY
NIGHT...BRINGING IN DRIER AND COOLER AIR. HOWEVER...I HAVE LEFT IN
CHANCE POPS DUE TO THE TIMING UNCERTAINTY MENTIONED ABOVE AS
A SLOWER ECMWF SOLUTION WOULD ALLOW CONVECTION TO LINGER THROUGH
THE EVENING.

.WEDNESDAY...THE AREA LOOKS TO DRY OUT ON WEDNESDAY AS A SURFACE
LOW AND TRAILING COLD FRONT GET PULLED OUT INTO THE ATLANTIC AND
DRY WESTERLY FLOW AT LOW LEVELS BECOMES ESTABLISHED. MAX TEMPS
WILL BE COOLER WITH HIGHS ONLY REACHING THE MID TO UPPER 70S.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
THE GLOBAL MODELS STILL DIFFER IN THE DETAILS OF THE ANOMALOUS
UPPER LOW THAT IS EXPECTED TO DEVELOP OVER THE EASTERN U.S. FOR
THE SECOND HALF OF THE WEEK. THE ECMWF DROPS THE LOW FURTHER TO
THE SOUTHEAST AND HAS A SHARP UPPER TROF MOVING THROUGH
THURSDAY AFTERNOON...BRINGING THE THREAT OF LOW TOPPED SHOWERS
AND MAYBE EVEN SOME GRAUPLE/SMALL HAIL WITH 500 MB TEMPS EXPECTED
TO DROP BELOW -25C. THE GFS KEEPS THE CORE AND THE GREATEST
INSTABILITY FURTHER NORTH...PROVIDING DRY CONDITIONS THURSDAY
AFTERNOON. GIVEN THAT THE ECMWF SOMETIMES OVER AMPLIFIES THESE
SITUATIONS...I HAVE STAYED ON THE LOWER END OF THE GUIDANCE AND
JUST HAVE A SLIGHT CHANCE OF SHOWERS OVER LANCASTER AND
CHESTERFIELD COUNTIES THURSDAY AFTERNOON. THE UPPER LOW SHOULD
START MOVING SLOWLY EAST BY FRIDAY AND THE WEEKEND...WITH A
GRADUAL WARMING TREND IN STORE AND PRECIP CHANCES QUITE LOW.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
VFR CONDITIONS EXPECTED OUTSIDE OF CONVECTION THROUGH THE EVENING
THEN MVFR CIGS RETURN TONIGHT.

ANOTHER ROUND OF NOCTURNAL STRATUS ASSOCIATED WITH ABUNDANT LOW
LEVEL MOISTURE AND A LOW LEVEL JET IS EXPECTED TO DEVELOP AFTER
08Z BUT SHOULD MIX OUT AROUND 15Z. CANNOT COMPLETELY RULE OUT
ISOLATED TO SCATTERED SHOWERS OVERNIGHT AS A WEAK UPPER LEVEL
DISTURBANCE CROSSES THE REGION. BEST CHANCE FOR CONVECTION WILL
BE MONDAY AFTERNOON INTO THE EVENING. HAVE INDICATED VCSH IN TAFS
GIVEN UNCERTAINTY OF TIMING AND EXACT LOCATION OF STORMS.

EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CIGS POSSIBLE BOTH
TUESDAY AND WEDNESDAY MORNINGS AS THE LOW LEVEL MOISTURE REMAINS
OVER THE AREA. ALSO...SCATTERED CONVECTION MAY CAUSE SOME BRIEF
MVFR/IFR CONDITIONS TUESDAY AFTERNOON/EVENING. CONDITIONS SHOULD
IMPROVE FOR THE END OF THE WEEK WITH MAINLY VFR EXPECTED.

&&

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

&&

$$


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