622  
FXUS61 KAKQ 010042  
AFDAKQ  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE WAKEFIELD VA  
842 PM EDT SUN APR 30 2017  
   
SYNOPSIS
 
 
BERMUDA HIGH PRESSURE PREVAILS OFF THE SOUTHEAST COAST TONIGHT  
INTO MIDDAY MONDAY. A COLD FRONT APPROACHES FROM THE WEST MONDAY  
AFTERNOON, AND PUSHES ACROSS THE REGION MONDAY NIGHT, WITH HIGH  
PRESSURE RETURNING TUESDAY AND WEDNESDAY.  
 

 
   
NEAR TERM /UNTIL 6 AM MONDAY MORNING/
 
 
QUICK UPDATE TO ACCOUNT FOR SOME SCT SHOWERS PUSHING ACROSS THE  
I-85 CORRIDOR IN THE SW CWA. THESE SHOWERS SHOULD QUICKLY  
DIMINISH IN AREAL COVERAGE THROUGH 02Z/10PM...WITH AN OTHERWISE  
QUIET, DRY NIGHT AHEAD. POTENTIAL FOR SOME DEVELOPING LOW  
STRATUS ONCE AGAIN TOWARDS MORNING, ESPECIALLY ALONG THE COASTAL  
PLAIN. OTHERWISE, PARTLY TO MOSTLY CLEAR AND MILD WITH EARLY  
MORNING LOWS 65-70.  
 
PREVIOUS VALID DISCUSSION...ISSUED 4PM EDT  
 
THE RIDGE ALOFT OVER THE SUB- TROPICAL WRN ATLANTIC WILL  
CONTINUE TO PREVAIL TONIGHT AS A COLD FRONT OVER THE MISSISSIPPI  
VALLEY PUSHES EWD TONIGHT. SURFACE HIGH PRESSURE WILL REMAIN  
ANCHORED OFF THE SOUTHEAST COAST, WITH A QUASI-STATIONARY  
BOUNDARY OVER THE DELMARVA LIFTING N AS A WARM FRONT.  
TEMPERATURES THIS AFTERNOON ARE GENERALLY IN THE LOW/MID 80S  
ACROSS THE REGION. THESE VALUES WILL SLOWLY FALL INTO THE 70S  
THIS EVENING, WITH OVERNIGHT LOWS IN THE MID/UPPER 60S. MOSTLY  
CLEAR THIS EVENING, WITH SOME PATCHY STRATUS DEVELOPING LATE  
TONIGHT.  
 

 
   
SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/
 
 
THE COLD FRONT APPROACHES FROM THE W MONDAY AFTN AS THE CENTRAL  
PLAINS TROUGH LIFTS INTO THE GREAT LAKES. THE FRONT IS EXPECTED  
TO SLOW AS IT PUSHES ACROSS THE APPALACHIANS WITH STRONG  
SURFACE HEATING TO THE LEE OF THE MOUNTAINS. THEREFORE, POPS  
SHOULD BE SLOW TO INCREASE THROUGH THE AFTN, AND MAINLY OVER THE  
PIEDMONT INITIALLY. THE RIDGE WILL HOLD STRONG ALONG THE COAST  
WITH THE ERN HALF OF THE AREA REMAINING DRY THROUGH MUCH OF THE  
DAY MONDAY. 500MB FLOW AHEAD OF THE TROUGH REACHES 70-80KT,  
WHICH YIELDS 0-6KM BULK SHEAR ~50KT. HOWEVER, MID-LEVEL LAPSE  
RATES (850-600MB) ARE RATHER POOR, BUT MUCH STEEPER AROUND  
500MB, AND THE NET RESULT IS 0-1KM MLCAPE VALUES OF 500-1000  
J/KG ONCE THE STRONGEST SYNOPTIC FORCING ARRIVES LOCALLY (MAINLY  
21-03Z). THE SPC DAY 2 MARGINAL RISK HAS BEEN EXPANDED EWD TO  
THE INTERIOR COASTAL PLAIN, WITH A SLIGHT RISK INTRODUCED FOR  
THE PIEDMONT. PW VALUES ~1.5IN COMBINED WITH STRONG FORCING  
COULD RESULT IS SOME LOCALLY MODERATE TO HEAVY RAIN. THE COLD  
FRONT CROSSES THE REGION MONDAY NIGHT AND PUSHES OFFSHORE BY 12Z  
TUESDAY. POPS TAPER OFF FROM NW-SE FROM 06-12Z AS DRIER AIR  
ARRIVES FROM THE NW. HIGHS MONDAY WILL GENERALLY BE 80-85F W,  
WITH MID/UPPER 80S FARTHER E (UPPER 70S FOR THE ATLANTIC COAST  
OF THE ERN SHORE. LOWS MONDAY NIGHT RANGE FROM THE UPPER 50S W  
TO THE LOW/MID 60S ALONG THE COAST.  
 
A SOUTH TO SOUTHWEST WIND WILL BECOME BREEZY BY MID MORNING AS  
THE SFC PRESSURE GRADIENT RESPONDS TO THE APPROACHING STRONG  
COLD FRONT. GUSTS AROUND 25-30 MPH SHOULD BE COMMON BY LATE  
MORNING...INCREASING TO SUSTAINED WINDS OF 20-25 MPH WITH GUSTS  
AVERAGING 30-35 MPH. MODEL CROSS SECTIONS OF LAPSE RATES (AND  
ESSENTIALLY THE MIXING LAYER) ARE SUPPORTIVE OF THESE SPEEDS,  
WHICH ARE HIGHER THAN MODEL GUIDANCE.  
 
A TROUGH ALOFT BUILDS OVER THE ERN CONUS TUESDAY AND DAMPENS TO  
A MORE ZONAL FLOW PATTERN BY WEDNESDAY. SURFACE HIGH PRESSURE  
BUILDS ACROSS THE SOUTHEAST STATES TUESDAY, THEN DISSIPATES  
WEDNESDAY AS A DRY COLD FRONT APPROACHES FROM THE N.  
TEMPERATURES WILL BE LOWER TUESDAY, BUT STILL ON THE WARM-SIDE  
OF NORMAL WITH HIGHS RANGING FROM THE MID 70S TO NEAR 80 UNDER A  
MOSTLY SUNNY SKY. MOSTLY CLEAR TUESDAY NIGHT WITH LOWS RANGING  
THROUGH THE 50S. MOSTLY SUNNY WEDNESDAY WITH HIGHS IN THE  
MID/UPPER 70S, AND LOCALLY UPPER 60S/LOW 70S FOR THE ATLANTIC  
COAST OF THE ERN SHORE.  
 
REMAINING BREEZY MONDAY NIGHT INTO TUESDAY DUE TO COLD AIR  
ADVECTION AND A CONTINUED TIGHTENED SFC PRESSURE GRADIENT BEHIND  
THE COLD FRONTAL PASSAGE. THE WIND BECOMES WESTERLY WITH SPEEDS  
AVERAGING 15 MPH WITH GUSTS AROUND 25 MPH INLAND AND 20 MPH  
WITH GUSTS AROUND 30 MPH...MAINLY AFTER MIDNIGHT MONDAY NIGHT.  
FOR TUESDAY, A WSW WIND WILL AVERAGE 20 MPH WITH GUSTS OF 25-30  
MPH AREAWIDE.  
 

 
   
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
 
 
SFC HIGH PRESSURE NORTH OF THE AREA SLIDES CLOSER TO THE  
NJ SHORE WEDNESDAY NIGHT AND EAST OF THE NEW ENGLAND COAST  
ON THURSDAY AS A WARM FRONT LIFTS NORTH INTO THE REGION.  
MEANWHILE, SFC LOW PRESSURE DEVELOPS OVER THE TN/OH VALLEYS  
INTO FRIDAY. SE/ONSHORE WINDS BECOME BREEZY AT THE COAST  
THURSDAY INTO THURSDAY NIGHT...BECOMING MORE S ON FRIDAY  
AFTER THE WARM FRONT LIFTS WELL NORTH OF THE AREA. DECENT  
AMOUNT OF UNCERTAINTY OF HOW/WHERE THE SFC LOW WILL DEVELOP  
AND WHERE IT WILL TRACK FRIDAY THROUGH SATURDAY NIGHT  
(INCLUDING WHEN ITS ASSOCIATED COLD FRONT WILL CROSS THE  
REGION). KEPT THE FORECAST FAIRLY GENERAL/BROAD-BRUSHED  
DURING THIS TIME. WEAK COLD AIR ADVECTION BEHIND THE LOW  
MAY BE REINFORCED BY ANOTHER COLDER SHOT OF CANADIAN, BUT  
AGAIN, THERE IS A LOT OF UNCERTAINTY AT THIS POINT. OVERALL,  
A BRIEF WARMING TREND CAN BE ANTICIPATED FOR THU NIGHT/FRI  
WITH A GRADUAL COOL DOWN WITH HIGHS BELOW NORMAL AND LOWS  
NEAR NORMAL.  
 

 
   
AVIATION /01Z MONDAY THROUGH FRIDAY/
 
 
A QUASI-STATIONARY FRONTAL BOUNDARY, CURRENTLY LOCATED JUST TO  
THE NORTH OF SALISBURY, WILL CONTINUE TO LIFT NORTH OF THE AREA  
OVERNIGHT TONIGHT. A COLD FRONT WILL APPROACH THE REGION LATE  
IN THE DAY ON MONDAY. MAINLY CLEAR SKIES ARE EXPECTED TO  
CONTINUE THROUGH THE FIRST- HALF OF THE NIGHT. SIMILAR TO THE  
PAST COUPLE OF NIGHTS, MVFR STRATUS MAY DEVELOP AT ALL TAF SITES  
GENERALLY AFTER 08Z. VISIBILITY RESTRICTIONS ARE NOT  
ANTICIPATED AS WINDS CONTINUE TO INCREASE THROUGH THE OVERNIGHT  
HOURS, LIMITING ANY FOG POTENTIAL. CONDITIONS RETURN TO VFR  
MAINLY AFTER 14Z MONDAY. WINDY CONDITIONS ARE ANTICIPATED FOR  
MONDAY WITH SOUTHWEST WINDS SUSTAINED AROUND 15-20 KNOTS AND  
GUSTS IN EXCESS OF 30 KNOTS POSSIBLE.  
 
OUTLOOK: THE COLD FRONT APPROACHES FROM THE WEST LATE IN THE DAY  
AND PASSES ACROSS THE REGION OVERNIGHT. THIS WILL BRING THE  
POTENTIAL FOR SHOWERS AND THUNDERSTORMS FROM LATE  
AFTERNOON/EARLY EVENING FOR RIC AND THEN SHIFTING TO THE COAST  
DURING THE EVENING THROUGH THE EARLY OVERNIGHT HOURS. ANY  
SHOWERS/THUNDERSTORMS HAVE THE POTENTIAL TO PRODUCE SUB-VFR  
CONDITIONS ALONG WITH LOCALLY STRONG WIND GUSTS. HIGH PRESSURE  
RETURNS TUESDAY AND WEDNESDAY AND SLIDES OFFSHORE THURSDAY AS  
LOW PRESSURE APPROACHES FROM THE WEST. THIS LOW PRESSURE SYSTEM  
POTENTIALLY IMPACTS THE REGION THURSDAY NIGHT AND INTO FRIDAY.  
 

 
   
MARINE
 
 
WINDS GENERALLY SW 10-15KT THROUGH TONIGHT...INCREASING  
INITIALLY WITH TYPICALLY DIURNAL PUSH AROUND SUNRISE AND  
CONTINUING TO INCREASE THROUGH MONDAY AS A STRONG COLD  
FRONT APPROACHES THE REGION. LOW-END SCA CONDITIONS TO  
BEGIN FOR THE BAY AROUND SUNRISE MONDAY MORNING WITH THE  
NORMAL DIURNAL PUSH. CURRITUCK SOUND AND ERN VA RIVERS  
TO EXPERIENCE LOW-END SCA WINDS BY MID MORNING...THEN  
WINDS/SEAS/WAVES INCREASE ALL WATERS IN THE AFTERNOON AS  
THE SFC PRESSURE GRADIENT REALLY TIGHTENS UP IN RESPONSE  
TO THE FRONT AS IT NEARS THE MOUNTAINS. S-SW WINDS WILL  
AVERAGE 15-25KT WITH GUSTS OF 25-30KT PRIMARILY MON AFTN  
INTO MON EVENING BEFORE THE FRONTAL PASSAGE. A BRIEF PERIOD  
OF GALE FORCE GUSTS AROUND 35 KT WILL BE POSSIBLE (ESPECIALLY  
OVER THE COASTAL WATERS) DURING THE FRONTAL PASSAGE LATE MON  
EVENING INTO THE OVERNIGHT HOURS. CANCELLED GALE WATCH SINCE  
ANY GALE GUSTS WILL BE RELATED TO CONVECTION/FRONT (RATHER  
THAN SYNOPTICALLY-DRIVEN) AND CAN BE HANDLED WITH SPECIAL  
MARINE WARNINGS AS NEEDED. SCA FLAGS HOISTED FOR ALL WATERS  
WITH BEGINNING AND END TIMES ADJUSTED. SEE WBCAKQMWW FOR  
MORE DETAILS. SEAS BUILD TO 4-6FT MON AFTN AND INCREASE TO  
5-8FT NORTH/4-6FT SOUTH MON NIGHT. WAVES ON CHES BAY BUILD  
TO 4FT BY LATE MON MORNING/EARLY AFTN WITH UP TO 5FT POSSIBLE  
IN THE MIDDLE OF CHES BAY MON EVENING.  
 
WINDS BECOME WSW BEHIND THE FRONT AFTER MIDNIGHT MON NIGHT  
AND THEN TURN MORE SW ON TUE. WIND SPEEDS SLOWLY DIMINISH  
WITHIN THIS TIMEFRAME...AVERAGING 15-20KT BY MID MORNING TUE.  
WAVES ON CHES BAY ANTICIPATED TO BE 2-3FT BY SUNRISE TUE.  
SEAS WILL BE SLOWER TO SUBSIDE BELOW 5FT UNTIL MID MORNING  
TUE FOR SRN COASTAL WATERS AND NOT UNTIL TUE EVENING FOR NRN  
COASTAL WATERS. SCA FLAGS INCREMENTALLY DROP OFF FROM SOUTH  
TO NORTH AS TUE PROGRESSES. AGAIN, PLEASE SEE WBCAKQMWW FOR  
FURTHER DETAILS.  
 
FAIRLY BENIGN CONDITIONS ANTICIPATED FOR WED/WED NIGHT WITH  
HIGH PRESSURE OVER THE AREA. VARIABLE AOB 10KT WED/N-NE  
AOB 15KT WED NIGHT. A WARM FRONT IS EXPECTED TO LIFT NORTH  
ACROSS THE WATERS THURSDAY AS LOW PRESSURE DEVELOPS OVER THE  
TN/OH VALLEYS INTO FRIDAY. SE/ONSHORE WINDS BECOME BREEZY WITH  
SPEEDS AVERAGING 15-20KT THU AFTN AT LEAST THROUGH FRI AFTN.  
SEAS ANTICIPATED TO BUILD TO 4-6FT AND PERSIST INTO SAT  
MORNING BEFORE SUBSIDING. SCA CONDITIONS SHOULD BE EXPECTED  
DURING THIS TIME.  
 

 
   
HYDROLOGY
 
 
FLOOD ADVISORY CONTINUES IN MECKLENBURG COUNTY, VA. VDOT STILL  
REPORTING NUMEROUS ROADS CLOSED IN THE KERR DAM AREA, CREATING  
ONGOING NAVIGATION CONCERNS.  
 

 
   
CLIMATE
 
 
RICHMOND AND NORFOLK WILL EACH ESTABLISH NEW RECORDS FOR THE  
WARMEST APRIL ON RECORD. BARRING ANY UNEXPECTED CHANGES, BOTH  
SITES WILL ESTABLISH NEW RECORDS BY GREATER THAN 1 DEGREE. THE  
FOLLOWING IS WITH DATA AS OF THE 29TH. UNOFFICIAL FINAL MONTHLY  
DATA WILL BE ADDED TOMORROW.  
 
APRIL 2017  
AVG TEMP RECORD  
LOCATION TO DATE AVG TEMP YEAR  
-------- ---- ---- ----  
RICHMOND 63.7 63.1 1994  
NORFOLK 66.0 65.3 1994  
 
****  
 
ALL 4 CLIMATE SITES BROKE RECORD HIGH MINIMUM TEMPS FOR  
4/28...4/29 AND FOR THE MONTH OF APRIL. BARRING ANY  
UNLIKELY QUICK TEMPERATURE DROPS, ANOTHER ROUND OF RECORD  
HIGH MINIMUMS WILL BE ESTABLISHED AT CLIMATE SITES FOR  
4/30. A RECORD MAXIMUM WAS TIED TODAY AT SALISBURY.  
SEE PNSAKQ FOR DETAILS.  
 
RECORD HIGH TEMPS FOR TODAY 4/30 (ACTUAL):  
RIC...93 IN 1974 (86)  
ORF...93 IN 1888 (89)  
SBY...86 IN 1974 (86, RECORD TIED)  
ECG...90 IN 1974 (86)  
 
RECORD HIGH MINIMUMS FOR TODAY 4/30:  
RIC...63 IN 2014  
ORF...67 IN 1994  
SBY...63 IN 1983  
ECG...65 IN 2014  
 

 
   
AKQ WATCHES/WARNINGS/ADVISORIES
 
 
MD...NONE.  
NC...NONE.  
VA...NONE.  
MARINE...SMALL CRAFT ADVISORY FROM 10 AM MONDAY TO 10 AM EDT TUESDAY  
FOR ANZ635-636-638.  
SMALL CRAFT ADVISORY FROM 10 AM MONDAY TO 8 AM EDT TUESDAY FOR  
ANZ633-637.  
SMALL CRAFT ADVISORY FROM 4 AM MONDAY TO 6 PM EDT TUESDAY FOR  
ANZ630>632-634.  
SMALL CRAFT ADVISORY FROM 2 PM MONDAY TO 4 PM EDT TUESDAY FOR  
ANZ654.  
SMALL CRAFT ADVISORY FROM 2 PM MONDAY TO 10 AM EDT TUESDAY FOR  
ANZ656-658.  
SMALL CRAFT ADVISORY FROM 2 PM MONDAY TO 11 PM EDT TUESDAY FOR  
ANZ650-652.  
 

 
 

 
SYNOPSIS...AJZ  
NEAR TERM...AJZ/MAM  
SHORT TERM...AJZ/BMD  
LONG TERM...BMD  
AVIATION...AJB/AJZ  
MARINE...BMD  
HYDROLOGY...  
CLIMATE...  
 
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