588
FXUS62 KRAH 151449
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1049 AM EDT THU MAY 15 2025
SYNOPSIS
UPPER LEVEL DISTURBANCES MOVING ATOP AN UPPER LEVEL RIDGE BUILDING
ACROSS THE SE US WILL SUPPORT MAINLY DIURNAL SHOWERS AND STORMS AND
UNSEASONABLY HOT TEMPERATURES TO END THE WORK WEEK. A SERIES OF COLD
FRONTS WILL MOVE THROUGH THE REGION OVER THE WEEKEND.
NEAR TERM /TODAY AND TONIGHT/
AS OF 1049 AM THURSDAY...
* ISOLATED/WIDELY SCATTERED STRONG/SEVERE CONVECTION POSSIBLE
ACROSS THE NORTHERN PIEDMONT AND NORTHERN COASTAL PLAIN THIS
AFTERNOON/EARLY EVENING
LITTLE UPDATES THIS MORNING AS THE FORECAST IS ON TRACK. SFC
OBSERVATIONS THIS MORNING DEPICTED A NORTHWARD ADVANCING WARM FRONT
BEHIND THE SLOWLY DECAYING STRATUS/FOG SHIELD IN THE NORTHERN
PIEDMONT/COASTAL PLAIN. THIS FEATURE WILL CONTINUE TO RIDE NORTH
SOMEWHERE INTO THE SOUTH-CENTRAL VA/NORTH-NORTHEASTERN NC LATER THIS
AFTERNOON. EMBEDDED WITHIN INCREASING WNWLY FLOW ALOFT AND A
SUBSTANTIALLY JUICY ATMOSPHERE, MID-LEVEL IMPULSES WILL INITIATE
CONVECTION OVER THE BLUE RIDGE MOUNTAINS IN VA EARLY THIS AFTERNOON.
A FEW ISOLATED STORMS MAY TRICKLE DOWN INTO OUR NORTHERN COASTAL
PLAIN/PIEDMONT AS THESE UPSTREAM CELLS INTERACT WITH THE ADVANCING
WARM FRONT. THERE REMAINS UNCERTAINTY, HOWEVER, WITH HOW MUCH
COVERAGE WE MAY ACTUALLY SEE AS SOME CAMS SIMULATE DRIER SOLUTIONS.
IF CONVECITON CAN REACH OUR AREA, FORECASTED HODOGRAPHS WOULD FAVOR
RIGHT-MOVING SUPERCELLS (ELONGATED AND CLOCKWISE-CURVED BETWEEN 2-5
KM) CAPABLE OF PRODUCING LARGE HAIL (POSSIBLY > 2 INCHES) AND
DAMAGING WIND GUSTS. FORECAST SOUNDINGS ACROSS NORTHERN AREAS
INDICATE VERY LIMITED LOW-LEVEL SHEAR, AND AS SUCH, THINK THE BETTER
TORNADO THREAT IS MORE-SO UP INTO VA TODAY. HOWEVER, IF THE WARM
FRONT LINGERS ACROSS OUR NORTHERN AREAS, THERE WOULD REMAIN SOME
CONCERN FOR A BRIEF ISOLATED TORNADO WHEREVER SFC WINDS MAY BACK
JUST AHEAD OF THE WARM FRONT.
ANY STRONGER STORMS WILL DISSIPATE WITH LOSS OF HEATING THIS
EVENING. OVERNIGHT SHOULD REMAIN RELATIVELY DRY, HOWEVER SHOWERS
ASSOCIATED WITH A DECAYING, UPSTREAM MCS MAY GENERATE SOME
MEASUREABLE RAINFALL THROUGH SUNRISE ACROSS WESTERN AREAS.
OTHERWISE, SOME PATCHY FOG MAY BE POSSIBLE ACROSS NORTHERN AREAS
EARLY FRIDAY MORNING.
PREVIOUS DISCUSSION FROM 350 AM...
TODAY:
UPPER LEVEL RIDGING WILL BUILD EASTWARD TODAY, BRINGING MODEST 500
MB HEIGHT RISES(40 M) AND SUPPRESSING WIDESPREAD CONVECTION.
HOWEVER, STRONG DIURNAL HEATING(AFTERNOON HIGHS MID/UPPER 80S)
WITHIN THE RESIDUAL MOIST AIRMASS AND STEEP MID-LEVEL LAPSE RATES
(7.5-8 DEG C/KM) FROM AN EXPANSIVE EML MOVING INTO THE REGION FROM
THE FROM THE SOUTHERN PLAINS/MEXICO, WILL CREATE A VERY UNSTABLE
ENVIRONMENT, WITH MLCAPE OF 2500-3500 J/KG.
WHILE THE PRIMARY SEVERE THREAT IS EXPECTED TO LIE ACROSS EASTERN VA
AND NORTHEASTERN NC, IF CONVECTION MOVING OFF THE BLUE RIDGE
MOUNTAINS CAN DRIFT FAR ENOUGH SOUTH INTO THE NORTHERN PIEDMONT AND
NORTHERN COASTAL PLAIN COUNTIES DURING THE AFTERNOON AND EVENING,
THE FAT CAPE PROFILES COUPLED WITH DEEP LAYER SHEAR OF 30-35 KTS
COULD SUPPORT POTENTIALLY VIGOROUS UPDRAFTS AND SUPERCELLS CAPABLE
OF PRODUCING LARGE HAIL AND WIND DAMAGE. AN ISOLATED TORNADO IS ALSO
POSSIBLE.
TONIGHT:
THE SEVERE THREAT DIMINISHES AFTER SUNSET, THOUGH SOME ISOLATED TO
WIDELY SCATTERED CONVECTION MAY RE-DEVELOP OVERNIGHT. FOG POTENTIAL
TONIGHT APPEARS SIGNIFICANTLY LOWER THAN THE PREVIOUS 2 NIGHTS, BUT
MAY STILL OCCUR IN MORE ISOLATED/PATCHY VARIETY IN AREAS(NORTHEAST)
RECEIVING HEAVY RAIN. WARM OVERNIGHT LOWS 65-70 F.
SHORT TERM /FRIDAY AND FRIDAY NIGHT/
AS OF 805 AM THURSDAY...
* A CONDITIONAL RISK OF SEVERE STORMS WILL EXIST ACROSS THE NRN HALF
OF CNTL NC ON FRI, BASED ON LOWER PREDICTABILITY, MESOSCALE
INFLUENCES FROM UPSTREAM CONVECTION ACROSS THE LWR OH VALLEY TODAY-
TONIGHT.
AN ANOMALOUSLY STRONG MID/UPR-LEVEL CYCLONE WITH 500 MB STANDARDIZED
HEIGHT ANOMALIES OF -4 TO 5 SIGMA AT THE START OF THE PERIOD WILL
PROGRESS ACROSS THE UPR MS VALLEY AND UPR GREAT LAKES, WHILE
WEAKENING. A SIGNIFICANT SHORTWAVE TROUGH, COMPRISED OF AT LEAST A
COUPLE OF PERTURBATIONS NOW DIGGING ACROSS THE GREAT BASIN, WILL
ROTATE THROUGH THE SRN AND SERN PERIPHERY OF THE CYCLONE AND ACROSS
THE OH VALLEY THROUGH THE END OF THE PERIOD. SOME DEGREE OF PHASING
MAY OCCUR BETWEEN THAT SHORTWAVE AND AN ENERGETIC SRN BRANCH JET
THAT WILL STREAM FROM THE SUB-TROPICAL SERN N. PACIFIC TO THE
CAROLINAS, AROUND THE NRN PERIPHERY OF A SUB-TROPICAL MID-LEVEL
HIGH, ONE WITH STANDARDIZED HEIGHT ANOMALIES OF 2-3 SIGMA, THAT WILL
DRIFT ACROSS FL. SEASONABLY STRONG MID-LEVEL WSWLY FLOW BETWEEN
THOSE FEATURES WILL ALSO INCLUDE A SERIES OF MCVS ACROSS THE MID-
SOUTH, LWR OH VALLEY AND SRN MIDDLE ATLANTIC, AND THROUGH THE NRN
PERIPHERY OF AN EXTENSIVE EML PLUME THAT WILL REMAIN ACROSS THE
SOUTHEAST. UNCERTAINTIES REGARDING THE PATH OF THESE FEATURES, AND
TO WHAT DEGREE THEY MAINTAIN INTENSITY EAST OF THE BLUE RIDGE EARLY
FRI, LEND LOWER THAN AVERAGE FORECAST CONFIDENCE FOR SENSIBLE
WEATHER IMPACTS OVER CNTL NC.
AT THE SURFACE, A LEE TROUGH WILL EXTEND ACROSS THE SRN MIDDLE
ATLANTIC AND CAROLINAS, WHILE OUTFLOW FROM ONGOING OR DECAYING
UPSTREAM MCSS MAY INFLUENCE PARTICULARLY THE NRN HALF OF CNTL NC.
EVEN IN THE CASE OF THE LATTER DECAYING MCS MOVING EAST OF THE BLUE
RIDGE, AS INDICATED BY BOTH THE 06Z HRRR AND 00Z GFS, A STRONG COLD
POOL AND SURFACE WIND GUSTS (~35-45 KT) COULD IMPACT THE NRN NC
PIEDMONT EARLY IN THE DAY, WITH APPRECIABLY COOLER TEMPERATURES THAN
CURRENTLY INDICATED FORECAST HIGHS IN THE UPR 80S THERE. AN
ALTERNATE AND EQUALLY AS LIKELY SCENARIO IS THE MCS AND MCV TRACK
FARTHER NORTH ACROSS THE VIRGINIAS, WITH GLANCING INFLUENCE ACROSS
THE NRN NC PIEDMONT AND NRN PERIPHERY OF CAPPING EML THAT COULD MORE
EASILY BE BREACHED, AND WHICH WOULD YIELD HOTTER AND MORE UNSTABLE
CONDITIONS THROUGHOUT CNTL NC, WITH UPR END STRONG TO EXTREME
INSTABILITY (IE. 3500-4500 J/KG) THAT WOULD FAVOR EXPLOSIVE
SUPERCELL DEVELOPMENT DURING THE AFTERNOON AND EVENING, AS DEPICTED
BY THE 00Z HRRR, HRW NSSL, AND HRW FV3.
AN ADDITIONAL EXTENSIVE BAND OF UPSTREAM CONVECTION AND OUTFLOW MAY
THEN REACH THE APPALACHIANS BY 12Z SAT, AND WHICH WILL PROVIDE
ANOTHER RISK OF SEVERE STORMS AS IT MOVES INTO THE LEE OF THE
APPALACHIANS, ON SAT.
LONG TERM /SATURDAY THROUGH TUESDAY/
AS OF 400 PM WEDNESDAY...
THE MID/UPPER LOW AND OCCLUDED SURFACE LOW WILL TRACK EAST ACROSS
SOUTHERN ONTARIO AND THE UPPER GREAT LAKES ON SATURDAY, DRAGGING A
COLD FRONT TO THE SOUTH THAT GUIDANCE IS IN GOOD AGREEMENT WILL PASS
THROUGH CENTRAL NC ON SATURDAY EVENING/NIGHT. INSTABILITY CONTINUES
TO LOOK MODERATE TO STRONG ALONG WITH 40+ KTS OF MID-LEVEL FLOW
(SIMILAR TO FRIDAY). HOWEVER, MOISTURE WITH THE FRONT DOES NOT LOOK
IMPRESSIVE, AS THE FLOW ALOFT IS STILL FROM A WESTERLY DIRECTION,
AND WE ONLY GET A GLANCING BLOW IN UPPER FORCING WITH THE LOW
TRACKING SO FAR TO OUR NORTH. ENSEMBLE MEAN QPF CONTINUES TO BE LESS
THAN A TENTH OF AN INCH. SO ONLY HAVE SLIGHT TO LOW CHANCE POPS IN
THE AFTERNOON AND EVENING, HIGHEST OVER THE NORTHERN PIEDMONT WHERE
AGAIN THE GREATEST UPPER FORCING WILL BE. STILL CAN'T RULE OUT A FEW
STRONG TO SEVERE STORMS. SATURDAY'S TEMPERATURES MAY BE KEPT DOWN A
BIT BY THE INCREASED PRECIPITATION CHANCES AND APPROACH OF THE COLD
FRONT, PARTICULARLY IN THE NW. BUT THEY SHOULD STILL BE QUITE WARM
WITH HIGHS IN THE MID-80S TO LOWER-90S. HEAT INDICES IN THE UPPER-
90S WILL AGAIN BE POSSIBLE IN THE SE.
OVERALL FORECAST CONFIDENCE DECREASES FOR THE REST OF THE PERIOD.
THE MID-LEVEL FLOW WILL TURN INCREASINGLY NW FROM SUNDAY INTO
TUESDAY, AS WE ARE CAUGHT BETWEEN THE LOW SLOWLY DRIFTING EAST OVER
NEW ENGLAND/SE CANADA AND RIDGING THAT STRENGTHENS AND BUILDS EAST
FROM THE PLAINS TO THE DEEP SOUTH AND TN VALLEY. AT THE SURFACE, A
SECONDARY BACKDOOR COLD FRONT LOOKS TO MOVE THROUGH CENTRAL NC
SOMETIME SUNDAY NIGHT OR MONDAY, AS THE GFS AND ECMWF START TO
DIVERGE ON HOW QUICKLY THE LOW OVER THE CANADIAN MARITIMES MOVES
EAST INTO THE ATLANTIC. THIS FRONT WILL BE QUASI-STATIONARY BUT
SHOULD REMAIN DRAPED TO OUR SOUTH AND WEST THROUGH TUESDAY, KEEPING
US RELATIVELY DRY AND STABLE. THE 12Z GFS AND ECMWF POTENTIAL FOR AN
MCS MOVING THROUGH IN THE NW FLOW ALOFT LATE MONDAY, BUT TIMING AND
PLACEMENT OF THESE SYSTEMS THIS FAR IN ADVANCE IS DIFFICULT TO
PINPOINT. SO ONLY HAVE SLIGHT CHANCE POPS IN THE SOUTH AND WEST FROM
SUNDAY THROUGH TUESDAY. GUIDANCE DEPICTS THE NEXT LOW MOVING NE FROM
THE CENTRAL PLAINS INTO THE UPPER GREAT LAKES ON TUESDAY AND
WEDNESDAY, WHICH MAY HELP PUSH THE BOUNDARY BACK NORTH AS A WARM
FRONT ON WEDNESDAY. BUT THERE IS STILL PLENTY OF DIVERGENCE IN
GUIDANCE ON THE LOW'S STRENGTH. REGARDLESS IT APPEARS SHOWER/STORM
CHANCES WILL INCREASE ON WEDNESDAY, SO HAVE CHANCE POPS RETURNING.
TEMPERATURE FORECAST CONFIDENCE IS LOW FROM SUNDAY ONWARD,
ESPECIALLY BY MIDWEEK, BUT THE OVERALL TREND SEEMS TO BE TRENDING A
BIT COOLER, ESPECIALLY ON THE ECMWF. AS COOL HIGH PRESSURE EXTENDS
SOUTH FROM THE HUDSON BAY INTO THE EASTERN US, EXPECT AT LEAST A
GRADUAL DROP IN TEMPERATURES, WITH HIGHS REACHING CLOSER TO NORMAL.
DEW POINTS SHOULD ALSO BECOME MORE COMFORTABLE, DROPPING INTO THE
50S.
AVIATION /11Z THURSDAY THROUGH MONDAY/
AS OF 630 AM THURSDAY...
LIFR TO MVFR RESTRICTIONS IN FOG WILL LIFT AND DISSIPATE AS SFC
MIXING INCREASES BETWEEN 13 TO 15Z, WITH KRWI BEING THE
LAST TERMINAL TO IMPROVE TO VFR. SCATTERED SHOWERS AND STORMS NEAR
THE EASTERN TERMINALS(KRWI AND KFAY) SHOULD PASS EAST OF THE AREA
BETWEEN 12-13Z. VFR CONDITIONS SHOULD DOMINATE, BUT STORMS MOVING
SE OUT OF VIRGINIA MAY IMPACT KRDU AND KRWI LATE THIS
AFTERNOON/EARLY EVENING, WITH BRIEF SUB-VFR RESTRICTIONS POSSIBLE.
LATEST MODEL GUIDANCE INDICATES MINIMAL FOG POTENTIAL TONIGHT/FRIDAY
MORNING.
OUTLOOK: CHANCES FOR DIURNAL ISOLATED TO SCATTERED SHOWERS AND
STORMS WILL CONTINUE THROUGH MUCH OF THE PERIOD. MORNING FOG AND
LOW STRATUS WILL BE POSSIBLE EACH MORNING, ESPECIALLY IN AREAS THAT
RECEIVED SIGNIFICANT RAINFALL THE PREVIOUS DAY.
RAH WATCHES/WARNINGS/ADVISORIES
DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR NCZ007>011-
021>028-038>043-076>078.
SYNOPSIS...CBL
NEAR TERM...LUCHETTI/CBL
SHORT TERM...MWS
LONG TERM...DANCO
AVIATION...CBL
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