758
FXUS62 KRAH 230700
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
300 AM EDT SAT MAY 23 2026
WHAT HAS CHANGED
* CONTINUED INCREASING CONFIDENCE IN WIDESPREAD RAIN, LOCALLY HEAVY
AT TIMES, THROUGH THE MIDDLE OF NEXT WEEK. RAINFALL AMOUNTS DURING
THIS TIME ARE EXPECTED TO RANGE FROM 2 TO 4 INCHES ON AVERAGE,
THOUGH LOCALLY HIGHER AMOUNTS WILL BE POSSIBLE.
KEY MESSAGES
AS OF 300 AM SATURDAY...
1) WAVES OF SHOWERS AND STORMS ARE EXPECTED AGAIN TODAY AND TONIGHT
WITHIN A MOIST AIRMASS AND SLOWLY RETREATING WEDGE FRONT
2) ABOVE AVERAGE CHANCES OF RAIN/CONVECTION WILL CONTINUE THROUGH AT
LEAST THE MIDDLE OF NEXT WEEK, DURING WHICH TIME A PLUME OF DEEP
MOISTURE WILL BE DIRECTED AROUND A SUB-TROPICAL HIGH AND ATOP A
FRONTAL ZONE THAT WILL WAVER OVER THE SRN MIDDLE ATLANTIC.
DISCUSSION
AS OF 300 AM SATURDAY...
KEY MESSAGE 1... WAVES OF SHOWERS AND STORMS ARE EXPECTED AGAIN
TODAY AND TONIGHT WITHIN A MOIST AIRMASS AND SLOWLY RETREATING WEDGE
FRONT
AN AREA OF LOW PRESSURE ALONG THE IN/OH BORDER WILL TRACK UP INTO
THE GREAT LAKES TONIGHT. AS THAT HAPPENS, THE CAD WEDGE FRONT WILL
GRADUALLY LIFT NORTHWARD, LIKELY STALLING OUT AS IT MAKES IT WAY
INTO NORTH AND WESTERN SECTIONS OF CENTRAL NC. THE LATEST SURFACE
ANALYSIS SHOWS THE WEDGE BOUNDARY STRETCHING FROM CENTRAL SC INTO
SOUTHEASTERN NC, TUCKED AS FAR WEST AS NORTHEAST GA. THE FORECAST
CHALLENGE CONTINUES TO BE WHERE THE FRONT ENDS UP LATER TODAY AND
TONIGHT. PERHAPS THE GFS IS THE SLOWEST ON THE NORTHWARD MOVEMENT,
KEEPING THE WEDGE BOUNDARY SOUTH OF THE TRIANGLE MUCH OF THE DAY,
WHILE NAM/ECMWF FASTER, LIFTING THE BOUNDARY THROUGH ALL BUT THE FAR
NW PIEDMONT. THE GENERAL CONSENSUS OF GLOBAL AND HIGH-RES GUIDANCE
SUGGESTS THE TRIAD STAYS NW OF THE BOUNDARY IN THE NE FLOW, WHILE
THE SANDHILLS TO SOUTHERN COASTAL PLAIN SEE THE BOUNDARY LIFT
THROUGH. OUR FORECAST FOLLOWS CLOSELY THE HRRR/NAM-NEST SOLUTIONS,
SUGGESTING THE BOUNDARY BECOMES DRAPED FROM PORTIONS OF THE SOUTHERN
PIEDMONT INTO THE TRIANGLE AND CENTRAL TO NORTHERN COASTAL PLAIN BY
THE AFTERNOON TO EARLY EVENING. HOWEVER, THE BOUNDARY COULD END UP
50-100 MILES NORTH OF SOUTH OF THIS LINE. REGARDLESS, IT WILL MAKE
FOR A WIDE RANGE IN HIGHS FROM THE UPPER 50S TO LOW 60S IN THE FAR
NW, TO SOME MIDDLE 80S IN THE FAR SOUTH AND EAST.
AS FOR RAIN CHANCES, MODEL GUIDANCE INDICATES SEVERAL ROUNDS OF
SHOWERS AND SOME STORMS TODAY AND TONIGHT, DRIVEN BY SEVERAL MID-
LEVEL DISTURBANCES AND EMBEDDED MCVS TRACKING IN THE MOIST SW FLOW
ALOFT. PRECIPITABLE WATER VALUES STAY SOME 150-170 PERCENT OF NORMAL
IN THE 1.5-1.8 INCH RANGE. INITIAL SHOWER ACTIVITY INTO MID-MORNING
WILL BE MOST PREVALENT ACROSS OUR WESTERN ZONES. HOWEVER, GUIDANCE
DOES DEPICT ANOTHER WAVE OF ENERGY DURING THE AFTERNOON AND EVENING
GRADUALLY TRACKING EAST FROM THE WESTERN PIEDMONT AND INTERACTING
WITH THE WEDGE FRONT NEAR THE US-1 CORRIDOR AND PERHAPS SEA-BREEZE
ALONG THE COASTAL PLAIN. ALONG/SOUTH OF THE BOUNDARY, SOME 1000-1500
J/KG OF CAPE IS PRESENT WITH DEEP-LAYER SHEAR OF 20-25 KTS. WHILE WE
ARE NOT OUTLOOKED FROM SPC, WE CANNOT RULE OUT A FEW ISOLATED SEVERE
GUSTS WITH POSSIBLE WET MICROBURSTS. SOME LOCALLY HEAVY RAINFALL
WILL BE POSSIBLE NEAR/ALONG THE WEDGE BOUNDARY. THE HREF AND REFS
ENSEMBLE SYSTEMS BOTH INDICATE A POSSIBLE SWATH OF 1-4 INCHES OF
RAIN STRETCHING FROM THE SOUTHERN PIEDMONT INTO THE CENTRAL TO
NORTHERN COASTAL PLAIN. WHERE THAT SETS UP WILL ULTIMATELY DEPEND ON
WHERE THE BOUNDARY ENDS UP STALLING.
KEY MESSAGE 2... ABOVE AVERAGE CHANCES OF RAIN/CONVECTION WILL
CONTINUE THROUGH AT LEAST THE MIDDLE OF NEXT WEEK, DURING WHICH TIME
A PLUME OF DEEP MOISTURE WILL BE DIRECTED AROUND A SUB-TROPICAL HIGH
AND ATOP A FRONTAL ZONE THAT WILL WAVER OVER THE SRN MIDDLE
ATLANTIC.
ANOMALOUSLY MOIST SWLY FLOW, WITH PWS AROUND 2" AND 150-190% OF
NORMAL, WILL BE DIRECTED FROM THE GULF TO THE SRN MIDDLE ATLANTIC
THROUGH WED, BETWEEN A SUB-TROPICAL HIGH THAT WILL RETROGRADE FROM
NEAR BERMUDA AND INTO THE SOUTH ATLANTIC COAST AND A TROUGH THAT
WILL RELOAD OVER THE SRN PLAINS AND LWR MS VALLEY. THE PREVAILING
PATTERN WILL ALSO DIRECT MCVS FROM UPSTREAM CONVECTION ACROSS NC.
THE SUB-TROPICAL HIGH WILL THEN WEAKEN AND RETREAT INTO THE
CARIBBEAN, AS A DEEP TROUGH DEVELOPS ACROSS ERN CANADA, ANOTHER
PROGRESSES INTO THE GREAT BASIN, AND A REX BLOCK DEVELOPS BETWEEN
THE TWO AND ACROSS CNTL NOAM (CENTERED OVER THE MS VALLEY) THROUGH
LATE WEEK. THAT BLOCKING PATTERN, AND MOSTLY NWLY FLOW ALOFT OVER
THE MIDDLE ATLANTIC, WILL THEN LIKELY PERSIST THROUGH NEXT WEEKEND
AND PROBABLY INTO THE FOLLOWING WEEK.
AT THE SURFACE, A SHARP AND WELL-DEFINED WEDGE FRONT, WITH 50S-60S F
AND CONTINUED COLD AIR DAMMING TO ITS WEST AND 70S F TO ITS EAST,
WILL LIKELY BISECT CNTL NC (INVOF US HWY 1) SUN MORNING. CAD EROSION
WILL LIKELY RESULT LATE MORNING THROUGH THE AFTERNOON, WITH A
NORTHWEST LOW PASSAGE AND RESIDUAL COLD POOL (DIABATIC, SOLAR
HEATING) SERVING AS THE EROSION SCENARIOS PER MULTIPLE NCSU STUDIES
ON THE TOPIC. BY LATE AFTERNOON, DIURNAL HEATING, INTO THE UPR 70S
NW TO LWR-MID 80S ELSEWHERE AND WITH UNSEASONABLY HUMID, UPR 60S TO
AROUND 70F SURFACE DEWPOINTS, WILL YIELD A WEAKLY TO MODERATELY
UNSTABLE AND UNINHIBITED AIRMASS OVER CNTL NC - ONE SUPPORTIVE OF
SCATTERED TO LOCALLY NUMEROUS CONVECTION.
SURFACE TROUGHING/CONVERGENCE, AND SOME DEGREE OF A (LIKELY
CONVECTIVELY/DIABATICALLY-REINFORCED) THETA-E GRADIENT WILL THEN
WAVER OVER VA/NC THROUGH WED-THU, WHILE A SUB-TROPICAL, BERMUDA HIGH
WILL OTHERWISE BULGE WWD AND ACROSS THE SOUTH ATLANTIC COAST. THE
SURFACE FRONT, AND DEEPER MOIST AXIS, WILL PROBABLY BE SHUNTED JUST
SOUTH OF CNTL NC BY THE END OF THE WEEK, DURING WHICH TIME HIGH
PRESSURE WILL BUILD FROM CNTL AND ERN CANADA TO THE MIDDLE ATLANTIC,
WHERE IT MAY LINGER INTO EARLY THE FOLLOWING WEEK, BENEATH AND
DOWNSTREAM OF THE AFOREMENTIONED, PERSISTENT REX BLOCKING PATTERN.
INFLUENCE FROM THE FEATURES NOTED ABOVE WILL FAVOR MULTI-DAY TOTAL
RAINFALL AMOUNTS OF 1-3", WITH LOCALLY HIGHER AMOUNTS THROUGH THU,
AFTER WHICH TIME THE TREND WILL PROBABLY BE TOWARD DRIER CONDITIONS
AMID THE AFOREMENTIONED RIDGING ACROSS THE REGION BY NEXT WEEKEND.
AVIATION /06Z SATURDAY THROUGH WEDNESDAY/
AS OF 215 AM SATURDAY...
AREAS OF LIFR/IFR CONDITIONS ARE PRESENT TO START THE TAF PERIOD.
WAVES OF SHOWERS/RAIN ARE EXPECTED TO CONTINUE TO MOVE ACROSS THE
AREA TODAY AND TONIGHT, MOST FAVORED ACROSS THE TRIAD TERMINALS OF
GSO/INT. TIMING OUT THESE WAVES OF RAIN WILL BE DIFFICULT GIVEN THE
SPREAD IN THE HREF ENSEMBLE MEMBERS, AS WELL AS THE GRADUALLY
RETREATING WEDGE FRONT. THE CONSENSUS FAVORS GSO/INT LIKELY STAYING
NORTHWEST OF THE FRONT IN THE LINGERING CAD AIRMASS. AS A RESULT,
THESE TERMINALS ARE LIKELY TO HOVER BETWEEN LIFR/IFR THROUGH MUCH OF
THE PERIOD. FURTHER TO THE EAST AND SOUTHEAST, THERE STILL REMAINS A
BIT OF SPREAD IN HOW FAR NORTH THE WEDGE FRONT LIFTS, BUT GOOD
CONSENSUS WOULD SUGGEST IT LIFTS NORTH OF FAY AND PERHAPS RWI FOR
ESE FLOW TO DEVELOP AND LIFTING TO MVFR OR BRIEFLY VFR AT FAY. RDU
IS LIKELY GOING TO BE ON THE BOUNDARY OF IFR/MVFR. A WAVE OF
SCATTERED SHOWERS AND STORMS MAY TRACK ACROSS THE EASTERN TERMINALS
IN THE LATE AFTERNOON TO EARLY EVENING TIMEFRAME AND THE LATEST
FORECAST INCLUDES A TEMPO/PROB30 TO COVER THIS THREAT SEEN IN
SEVERAL HREF MEMBERS. LIFR/IFR CONDITIONS ARE LIKELY TO REDEVELOP
SAT NIGHT AT ALL TERMINALS.
OUTLOOK: THE CAD REGIME WILL START TO BREAK DOWN ON SUNDAY, BUT
LIFR/IFR STRATUS WILL STILL BE POSSIBLE INTO MONDAY MORNING. DAILY
SHOWER/STORM CHANCES WILL PERSIST THROUGH THE MIDDLE OF NEXT WEEK.
CLIMATE
RECORD LOW MAXIMUM TEMPERATURES:
MAY 23: KGSO: 59/1931
RECORD HIGH MINIMUM TEMPERATURES:
MAY 23: KFAY: 72/2011
MAY 24: KRDU: 70/2011 KFAY: 72/2000
MAY 25: KGSO: 70/2019 KRDU: 71/2019 KFAY: 71/2019
MAY 26: KGSO: 70/2019 KRDU: 73/2011 KFAY: 75/2004
MAY 27: KGSO: 72/1991 KRDU: 72/1991 KFAY: 72/2006
MAY 28: KGSO: 70/2012 KRDU: 74/1914
MAY 29: KRDU: 72/2012 KFAY: 73/2018
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...KREN/MWS
AVIATION...KREN
CLIMATE...RAH
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