-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 210706
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
305 AM EDT MON JUL 21 2014

.SYNOPSIS...A LOW PRESSURE AREA WILL HOLD OVER THE DEEP SOUTH
THROUGH TUESDAY... RESULTING IN A MOIST ATLANTIC FLOW FROM THE
SOUTHEAST INTO NORTH CAROLINA... AND UNSETTLED WEATHER TO START THE
WORK WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 235 AM MONDAY...

TODAY THROUGH TONIGHT: A DAMP AND VOLATILE ATMOSPHERE WILL HOLD OVER
CENTRAL NC AT LEAST THROUGH TONIGHT. THE LATEST SURFACE ANALYSIS
SHOWS A FRONTAL ZONE STRETCHING ACROSS THE GULF COAST THROUGH
CENTRAL GA/SC AND ACROSS SE NC... ASSOCIATED WITH A MID LEVEL TROUGH
OVER THE INTERIOR SOUTHEAST STATES AND MIDSOUTH. THIS TROUGH ALOFT
DEEPENS TO A BAGGY CLOSED LOW OVER SRN AL/GA BY TONIGHT... WITH A
WEAK BUT DISTINCT SHEAR AXIS STRETCHING NE ACROSS NC. PW VALUES ARE
ALREADY ON THE HIGH SIDE (120-140% OF NORMAL) AND ARE PROJECTED TO
RISE FURTHER... SURPASSING 2 INCHES OVER NEARLY THE ENTIRE CWA AND
PERHAPS 2.25 INCHES IN THE SE CWA... AS LOW LEVEL FLOW REMAINS FROM
THE SSE AND DRAWS IN ATLANTIC MOISTURE WHILE PRONOUNCED MID LEVEL
MOISTURE AND CONVECTIVE DEBRIS CLOUDS PERSIST WITHIN A WEAK STEERING
REGIME. THE LATEST HIGH-RES AND CONVECTION-ALLOWING MODELS SUGGEST
THAT THE PIEDMONT/WRN SANDHILLS WILL SEE THE GREATEST COVERAGE OF
SHOWERS AND ISOLATED STORMS THROUGH EARLY AFTERNOON... WHICH WOULD
THEN DRIFT EASTWARD INTO THE ERN SANDHILLS/COASTAL PLAIN DURING THE
AFTERNOON AND EARLY EVENING... BEFORE DECREASING IN COVERAGE BY
MIDNIGHT. THE GENERAL AGREEMENT ON THIS EVOLUTION BOOSTS FORECAST
CONFIDENCE... AND WILL FOLLOW THIS TREND IN THE FORECAST WITH GOOD
CHANCE POPS EAST AND LIKELY WEST EARLY... TRENDING DOWN IN THE WEST
AND UP IN THE EAST THIS AFTERNOON. BUT GIVEN THAT THE FLOW IS SO
WEAK WITH AN INCREASINGLY MOIST COLUMN AND SUBTLE MESOSCALE
BOUNDARIES GENERATED BY OUTFLOWS AND DIFFERENTIAL HEATING... SHOWERS
AND STORMS COULD POP UP ANYWHERE TODAY AND SIMPLY MEANDER. SLOW
STORM MOTION AND A FAIRLY DEEP WARM LAYER (AROUND 3.5 KM) TO FOSTER
WARM RAIN PROCESSES WILL BRING A RISK OF LOCALLY HEAVY RAINFALL
TODAY... ALTHOUGH NOT OVER A LARGE ENOUGH AREA TO NECESSITATE A
FLASH FLOOD WATCH AT THIS TIME. RAINFALL COULD BE EXACERBATED OVER
THE FAR WRN PIEDMONT WHERE LOW LEVEL MOIST UPGLIDE ATOP THE
RETREATING SHALLOW SURFACE RIDGE MAY ENHANCE LIFT. WILL TREND POPS
DOWN TO LOWER CHANCE TONIGHT... LOWER IN THE NE AND BETTER IN THE SW
WHERE MODELS SHOW SLIGHTLY BETTER MOISTURE TRANSPORT. CONSIDERABLE
CLOUDINESS WILL CUT DOWN ON HEATING TODAY ESPECIALLY EAST AND SE...
AND EXPECT HIGHS FROM THE LOW 80S NW TO MID 80S IN THE COASTAL
PLAIN. LOWS 68-72... LARGELY FOLLOWING PERSISTENCE. -GIH

&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
-- Changed Discussion --
AS OF 300 PM MONDAY...

THE BAGGY LOW OVER SRN AL IS EXPECTED TO DRIFT WESTWARD TUE/TUE
NIGHT TOWARD LA... NUDGING THE WEAK SHEAR AXIS ALOFT TO OUR WEST...
WHICH IN TURN BUMPS THE DIFFUSE SURFACE FRONTAL ZONE WESTWARD TOWARD
THE NC FOOTHILLS. PW IS EXPECTED TO HOLD AT OR ABOVE 2.0 INCHES...
WITH A SURGE IN LOW LEVEL MOISTURE TRANSPORT BY AFTERNOON. MODELS
GENERATE SPARSE PRECIP THROUGH MIDDAY MAINLY IN THE FAR SOUTH AND
FAR WRN PIEDMONT... THEN SPREAD NUMEROUS SHOWERS OVER THE WRN
PIEDMONT AND BACK TO THE FOOTHILLS IN THE AFTERNOON. MODELS DEPICT
MARGINAL TO MODERATE INSTABILITY BUT WITH WEAK DEEP LAYER SHEAR...
EXPECT ANOTHER ROUND OF MAINLY NON-SEVERE MULTICELL CLUSTERS
PRODUCING POCKETS OF HEAVY DOWNPOURS. WILL HAVE THE HIGHEST POPS IN
THE NW AND FAR WRN CWA AND LOWER POPS ELSEWHERE... AS OVERALL LIFT
IS TEMPERED BY MODEST HEIGHT RISES. SLIGHTLY GREATER SUNSHINE IS
ANTICIPATED WITH SLIGHTLY LOWER CONVECTION COVERAGE AND SIMILAR
THICKNESSES... SO EXPECT TUE TEMPS TO TOP OUT A BIT HIGHER THAN
TODAY... 85-89. LOWS TUE NIGHT 69-73 WITH POPS LOWERING TO SLIGHT
CHANCE. -GIH
-- End Changed Discussion --

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 230 AM MONDAY...

WEDNESDAY THROUGH FRIDAY: AN UPPER LEVEL TROUGH WILL APPROACH AND
MOVE INTO CENTRAL NC DURING THIS PERIOD. EXPECT THE USUAL SUMMERTIME
DIURNAL SHOWERS AND STORMS FOR WEDNESDAY AS A THE PIEDMONT TROUGH
SETS UP OVER THE AREA AND SURFACE WINDS SHIFT TO SOUTHWESTERLY. THE
INCREASING WARM MOIST SOUTHWEST FLOW WILL YIELD HIGHS AROUND 90
DEGREES AND LOWS IN THE LOW TO MID 70S. PWAT VALUES WILL BE BETWEEN
1.50 AND 2.00 INCHES...AND WITH CAPE AROUND 1500 J/KG AND RELATIVELY
WEAK SHEAR...EXPECT THE MAIN STORM THREATS TO BE HEAVY RAIN AND
STRONG GUSTY WINDS. THE UPPER LEVEL TROUGH WILL BE SLOW TO TRAVERSE
THE CAROLINAS AT THE END OF THE WORK WEEK. THE 00Z GFS INDICATES AN
INITIAL FRONT MOVING INTO CENTRAL NC THURSDAY NIGHT INTO FRIDAY
MORNING...WITH WINDS VEERING TO NORTHWESTERLY...AND STALLING OVER
THE AREA ON FRIDAY. A SECONDARY FRONT ASSOCIATED WITH THE MAIN PUSH
OF COOLER AIR IS EXPECTED TO MOVE INTO THE REGION LATE FRIDAY/FRIDAY
NIGHT...WITH HIGH PRESSURE OVER THE OH VALLEY. THE HIGHEST CHANCES
FOR SHOWERS AND STORMS IN THE NORTHWEST AND LOWEST CHANCES IN THE
SOUTHEAST ON THURSDAY...WITH THE REVERSE BEING THE CASE FOR FRIDAY.
HIGHS THURSDAY WILL BE MAINLY IN THE LOW TO MID 90S...AND OVERNIGHT
LOWS IN THE UPPER 60S TO LOW 70S. WITH THE NW WINDS ON FRIDAY...
EXPECT HIGHS 3-5 DEGREES COOLER THAN THURSDAY...MID TO UPPER 80S...
AND LOWS IN THE MID 60S TO AROUND 70 DEGREES.

SATURDAY AND SUNDAY: THE AFOREMENTIONED HIGH OVER THE OH VALLEY
WEAKENS AND THE BOUNDARY THAT LINGERED ACROSS THE AREA BECOMES
WASHED OUT OVER THE WEEKEND. GIVEN THE LACK OF A DOMINATING SURFACE
FEATURE AND THE GENERAL TROUGHINESS ALOFT...EXPECT A RETURN TO MORE
SEASONAL CONDITIONS FOR THE WEEKEND...WITH CHANCES FOR AFT/EVE
SHOWERS AND STORMS AND NEAR NORMAL TEMPERATURES...HIGHS IN THE UPPER
80S TO AROUND 90 DEGREES AND LOWS IN THE UPPER 60S TO LOW 70S.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AS OF 130 AM MONDAY...

SMALL CLUSTERS OF SHOWERS AND A FEW STORMS WILL PERSIST OVER CENTRAL
NC FOR MUCH OF THE TAF VALID PERIOD... BUT CONFIDENCE IS LOW AS TO
WHICH AIRFIELDS WILL BE MOST AFFECTED... AS SHOWERS/STORMS COULD
FORM ANYWHERE AND MEANDER/MOVE SLOWLY AROUND THE AREA. BUT IT
APPEARS THAT INT/GSO WILL SEE THE BEST COVERAGE THROUGH TODAY. A
WEAK TROUGH ALOFT OVER THE DEEP SOUTH IS EXPECTED TO CLOSE OFF INTO
A LOW OVER AL/GA TODAY AND TONIGHT... WHICH WILL KEEP A VERY MOIST
AND UNSETTLED ATMOSPHERE OVER NC... WITH A LIGHT FLOW FROM THE SE
AND S DRAWING IN ATLANTIC MOISTURE. GSO/INT AND TO A LESSER EXTENT
RDU HAVE THE BEST CHANCE OF SEEING MVFR CONDITIONS WITHIN
SHOWERS/STORMS THROUGH DAYBREAK. OTHERWISE... EVEN AWAY FROM
SHOWERS/STORMS... INT/GSO/RDU HAS A GOOD CHANCE OF SEEING IFR-LIFR
CIGS/VSBYS 08Z-13Z... AS THEY`VE SEEN THE MOST PRECIP IN THE LAST 24
HRS RESULTING IN A WET GROUND... SUSCEPTIBLE TO FOG/STRATUS GIVEN
THE LIGHT SURFACE WINDS. RWI/FAY ARE EXPECTED TO SEE A SHORTER
PERIOD OF MVFR-IFR CONDITIONS IN THE 08Z-13Z TIME FRAME. THESE CIGS
ARE EXPECTED TO LIFT SLOWLY AFTER DAYBREAK BUT STAY MVFR UNTIL
AROUND NOON... WHEN VFR CONDITIONS SHOULD RETURN WITH CIGS BASED AT
10 000 TO 15 000 FT AGL... ALTHOUGH LINGERING MVFR CIGS REMAIN
POSSIBLE THROUGH THE AFTERNOON. MORE SUB-VFR SHOWERS AND STORMS ARE
LIKELY TO DEVELOP AND DRIFT TO THE N OR NW TODAY THROUGH TONIGHT...
AND IT APPEARS ALL CENTRAL NC AIRFIELDS HAVE AN EQUAL CHANCE OF
SEEING SUCH STORMS LATER TODAY INTO TONIGHT.

LOOKING BEYOND 06Z TONIGHT... GOOD CHANCE OF IFR CIGS REDEVELOPING
BY LATE EVENING OR SOON AFTER MIDNIGHT TONIGHT... LASTING THROUGH
THE NIGHT... AT ALL TAF SITES... ACCOMPANIED BY MVFR FOG. THESE
SHOULD LIFT TO VFR BY LATE TUE MORNING. PATCHY SHOWERS AND ISOLATED
STORMS WILL REMAIN A GOOD BET THROUGH TONIGHT... WITH A LOW LEVEL
FLOW FROM THE EAST OR SE. SUB-VFR CONDITIONS SHOULD RETURN ONCE
AGAIN TUE NIGHT-WED MORNING AS THE MOIST UNSETTLED PATTERN HOLDS.
SCATTERED TO NUMEROUS SHOWERS AND STORMS ARE EXPECTED EACH DAY...
MAINLY AFTERNOON THROUGH EVENING... WITH CHANCES IMPROVING
EACH DAY THROUGH FRI. -GIH

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...KCP
AVIATION...HARTFIELD