318
FXUS62 KRAH 020619
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
220 AM EDT SAT MAY 2 2026
WHAT HAS CHANGED
* MOST GUIDANCE DEPICT A CONTINUED DOWNWARD TREND IN FORECAST
RAINFALL AMOUNTS ON SATURDAY.
KEY MESSAGES
AS OF 300 PM FRIDAY...
1) UNSEASONABLY COOL, WITH A WETTING RAIN (0.10" OR GREATER) LIKELY
OVER ALL BUT THE NW PIEDMONT ON SATURDAY.
2) BELOW AVERAGE TEMPERATURES ON SUNDAY WILL MODERATE AND BECOME
ABOVE AVERAGE BY TUESDAY WITH A RISK OF SHOWERS AND STORMS LATE
WEDNESDAY INTO THURSDAY WITH COOLER WEATHER FOR FRIDAY.
3) MARGINAL FIRE WEATHER CONCERNS FOR MONDAY AND TUESDAY WITH A
SOMEWHAT DRY AND INCREASINGLY GUSTY PATTERN.
DISCUSSION
AS OF 300 PM FRIDAY..
KEY MESSAGE 1... UNSEASONABLY COOL, WITH A WETTING RAIN (0.10" OR
GREATER) LIKELY OVER ALL BUT THE NW PIEDMONT ON SATURDAY.
A POSITIVELY-TILTED MID/UPR-LEVEL TROUGH WILL AMPLIFY ACROSS THE
PLAINS AND MS VALLEY TONIGHT AND ACROSS AND OFFSHORE THE MIDDLE
ATLANTIC SAT-SAT NIGHT, WHILE A LOW-LEVEL FRONTAL ZONE WILL
STRENGTHEN AND PROGRESS SLOWLY ACROSS THE NERN GULF AND SOUTH
ATLANTIC COASTS. IN THE MEANTIME, 850 MB-CENTERED SLY FLOW AND WARM,
MOIST ADVECTION AND LIFT, BENEATH THE EXIT REGION OF AN ENERGETIC
(~140 KT) SRN STREAM UPR-LEVEL JET, WILL PROGRESS ACROSS CNTL AND
ERN NC THROUGH THIS EVENING. THE FLOW IN THE LAYER WILL THEN VEER TO
WLY AND NWLY INTO THE AFOREMENTIONED, STRENGTHENING FRONTAL ZONE
ALONG THE COAST OVERNIGHT.
THE 850 MB-CENTERED LIFT WILL CONTINUE TO SUPPORT THE MAINTENANCE OF
PATCHES OF LIGHT RAIN THIS AFTERNOON AND EVENING ACROSS THE
SANDHILLS AND COASTAL PLAIN. RAIN WILL THEN REDEVELOP AND BECOME
INCREASINGLY-WIDESPREAD LATE TONIGHT-SAT, AS THE POSITIVE TILT
TROUGH PIVOTS EWD AND CAUSES THE AREA OF WIDESPREAD RAIN NOW ACROSS
THE GULF COAST STATES TO BUCKLE NWD AND OVERSPREAD CNTL-ERN NC. QPF
HAS CONTINUED TO TREND LOWER ACROSS MOST GUIDANCE, WITH THE NW EDGE
OF THE PRECIPITATION SHIELD LIKELY TO EXTEND ACROSS THE NW PIEDMONT.
50TH PERCENTILE VALUES FROM THE GEPS, EPS AND GEFS ALL DEPICT ~0.01"
AT GSO, ~0.25" AT RDU, AND A SPREAD OF A THIRD TO THREE QUARTERS OF
AN INCH AT FAY. LREF AND HREF PROBABILITIES OF A WETTING RAIN OF AT
LEAST A TENTH OF AN INCH ARE 60% OR GREATER OVER ALL BUT THE NW
PIEDMONT, WITH SIMILAR PROBABILITIES OF A QUARTER INCH OR GREATER
FROM NEAR RALEIGH AND POINTS SEWD.
IT WILL ALSO BE QUITE COOL SAT, WITH TEMPERATURES 10-20 F BELOW
AVERAGE AND LIKELY TO BREAK THE RECORD LOW MAXIMUM OF 61F AT FAY.
LATE AFTERNOON WEST TO EAST CLEARING ACROSS THE WRN PIEDMONT, AND A
GENERAL LACK OF RAIN AND EARLIER DIABATIC COOLING, MAY SUPPORT LOW-
MID 60S THERE, WITH 55-60 EXPECTED ELSEWHERE. CONTINUED WEST TO EAST
CLEARING SAT NIGHT WILL FAVOR GOOD RADIATIONAL COOLING CONDITIONS
AND LOWS IN THE UPR 30S TO MID 40S, AND WITH THE DEVELOPMENT OF
AREAS OF FOG AND/OR LOW STRATUS ESPECIALLY WHERE EARLIER RAIN
OCCURS.
KEY MESSAGE 2... BELOW AVERAGE TEMPERATURES ON SUNDAY WILL MODERATE
AND BECOME ABOVE AVERAGE BY TUESDAY WITH A RISK OF SHOWERS AND
STORMS LATE WEDNESDAY INTO THURSDAY WITH COOLER WEATHER FOR FRIDAY.
COOL HIGH PRESSURE AND MORNING LOW-LEVEL THICKNESS VALUES IN THE
1320S WILL RESULT IN A CHILLY START TO SUNDAY. DESPITE A GOOD DEAL
OF SUNSHINE HIGHS WILL RANGE IN THE MID TO UPPER 60S, OR ABOUT 6 TO
12 DEGREES BELOW AVERAGE.
THE SURFACE HIGH WILL QUICKLY SHIFT EAST, SUPPORTING THE DEVELOPMENT
OF A RETURN FLOW WITH MODERATING TEMPERATURES, A GRADUAL INCREASE IN
MOISTURE AS WELL AS WARM GUSTY AFTERNOON WINDS. HIGHS ON MONDAY AND
TUESDAY SHOULD WARM ABOVE AVERAGE AND RANGE IN THE UPPER 70S TO
LOWER 80S. THE MIXING DEPTH WILL INCREASE AND SUPPORT GUSTY
AFTERNOON WINDS WITH GUSTS UP TO 20 TO 25 MPH ON MONDAY AND PERHAPS
30 MPH ON TUESDAY, ESPECIALLY ACROSS THE WESTERN AND NORTHERN AREAS.
NORTHERN AND SOUTHERN STREAM TROUGHS ACROSS THE DESERT SOUTHWEST AND
CANADIAN PRAIRIES EARLY IN THE WEEK WILL PHASE AS THEY SHIFT EAST
ACROSS THE CENTRAL AND EASTERN U.S. ON WEDNESDAY AND THURSDAY. HOW
THESE SYSTEMS PHASE WILL IMPACT THE TIMING AND PATTERN OF
PRECIPITATION AND THE EVOLUTION OF A SOUTHEASTWARD ADVANCING COLD
FRONT. ENSEMBLE GUIDANCE IS STILL VARIED WITH THE TIMING OF THESE
SYSTEMS WITH A TENDENCY FOR THE BEST CHANCE OF PRECIPITATION
THURSDAY, ESPECIALLY THE AFTERNOON, WHILE SOME GUIDANCE SUPPORTS A
MORE PROGRESSIVE PATTERN WITH PRECIPITATION CHANCES ON WEDNESDAY
AFTERNOON AND NIGHT. THE MID AND UPPER LEVEL FLOW IS RATHER STRONG
WITH 500MB WINDS ACROSS THE SOUTHERN APPALACHIANS RANGING FROM 80 TO
90KTS, SUPPORTING SOME DEEP-LAYER SHEAR. A LITTLE MORE UNCERTAIN IS
THE DEGREE OF DESTABLIZATION THE THE TIMING OF ANY POTENTIAL
CONVECTION WITH DEW POINTS CREEPING INTO THE UPPER 50S TO LOWER 60S.
AS NOTED IN THE PREVIOUS SHIFTS, MANY OF THE AI SEVERE CONVECTIVE
GUIDANCE TOOLS INDICATE THE POTENTIAL FOR SOME STRONGER STORMS LATE
WEDNESDAY OR THURSDAY, BUT THE SIGNAL ISN'T SUPER ROBUST AT THIS
TIME. SOME MUCH NEEDED RAIN APPEARS A GOOD BET ALTHOUGH AVERAGE
RAINFALL AMOUNTS WILL BE LIGHT AND RANGE AROUND OR PERHAPS A LITTLE
LESS THAN 0.25 INCHES. THE CHANCES OF A MORE SIGNIFICANT RAIN, MORE
THAN A HALF INCH, ARE LESS THAN 25%.
A NORTHWEST FLOW OF COOLER AND DRIER AIR ARRIVES LATE THURSDAY INTO
FRIDAY WITH COOLER AND DRIER WEATHER EXPECTED. -BLAES
KEY MESSAGE 3... MARGINAL FIRE WEATHER CONCERNS FOR MONDAY AND
TUESDAY WITH A SOMEWHAT DRY AND INCREASINGLY GUSTY PATTERN.
SURFACE HIGH PRESSURE ACROSS THE EASTERN U.S. ON SUNDAY SHIFTS EAST
AND OFFSHORE ON MONDAY BEFORE A RETURN FLOW OF MORE MOIST AIR MOVES
INTO THE REGION TOWARD MID WEEK. EXPECT RH VALUES TO END UP A LITTLE
LOWER THAN GUIDANCE WITH ADJUSTED MINIMUM RH VALUES ON SUNDAY
BOTTOMING OUT IN THE 25 TO 30% RANGE, JUST UNDER OR AROUND 30% ON
MONDAY AND AROUND OR JUST OVER 30% ON TUESDAY. WHILE THE RH IS
LOWEST EARLIER IN THE PERIOD, WIND GUSTS WILL LIKELY BE SOMEWHAT
LIMITED ON SUNDAY AND BUT INCREASE NOTABLY ON MONDAY AND ESPECIALLY
TUESDAY. THUS FIRE WEATHER PARAMETERS DO NOT LINE UP OPTIMALLY AND
WHILE MARGINAL FIRE DANGER CONCERNS CANNOT BE COMPLETELY RULED OUT,
THE RISK APPEARS SOMEWHAT LIMITED.
AVIATION /06Z SATURDAY THROUGH WEDNESDAY/
AS OF 220 AM SATURDAY...
ADVERSE AVIATION CONDITIONS ARE LIKELY EARLY THIS MORNING THROUGH
MUCH OF THIS AFTERNOON OVER S AND E TERMINALS, AS WIDESPREAD RAIN
MOVES THROUGH SOUTHERN AND EASTERN NC, ASSOCIATED WITH SURFACE LOW
PRESSURE TRACKING FROM THE GULF COAST TO THE NE ACROSS THE SOUTHEAST
COAST. FAY WILL SEE THE POOREST CONDITIONS, WITH SPORADIC MVFR CIGS
BECOMING MORE SOLIDLY MVFR AFTER 09Z WITH RAIN SPREADING IN, AND
SEVERAL HOURS OF IFR CIGS AND VSBYS ARE POSSIBLE 15Z-19Z. RDU AND
RWI WILL BE SLIGHTLY BETTER, AS THE RAIN THAT MOVES IN WILL BE
LIGHTER, AND MOSTLY VFR CIGS ARE EXPECTED BUT MAY BECOME MVFR FOR A
TIME BETWEEN 13Z AND 19Z. INT/GSO ARE LIKELY TO SEE JUST VERY LIGHT
RAIN AT MOST, WITH VFR CIGS PREVAILING. THE LOW WILL PUSH OFF THE NC
COAST LATE TODAY THROUGH EARLY EVENING, RESULTING IN A W TO E ENDING
OF RAIN THROUGH THE LAST 6 HOURS OF THE TAF VALID PERIOD, AND CIGS
ARE EXPECTED TO TREND TO VFR AREAWIDE AFTER 20Z-22Z AT RDU/RWI AND
AFTER 02Z AT FAY. SURFACE WINDS WILL BE MOSTLY UNDER 10 KTS FROM THE
N OR NE.
LOOKING BEYOND 06Z SUN, VFR CONDITIONS SHOULD DOMINATE THROUGH AT
LEAST EARLY WED, UNDER THE INFLUENCE OF HIGH PRESSURE. AS THIS HIGH
MOVES FURTHER OFFSHORE, A WARM AND MOIST SOUTHWEST FLOW AHEAD OF AN
APPROACHING COLD FRONT WILL BRING INCREASING CHANCES FOR SUB-VFR
CONDITIONS AND SCATTERED TO NUMEROUS SHOWERS AND STORMS, STARTING
WED EVENING.
CLIMATE
RECORD LOW MAXIMUM TEMPERATURES:
MAY 2:
KRDU: 53/1939
KFAY: 61/1963
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...MWS/BLAES
AVIATION...HARTFIELD
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