Area Forecast Discussion
Issued by NWS Sterling, VA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KLWX 251913
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
313 PM EDT SAT APR 25 2015

.SYNOPSIS...
LOW PRESSURE OVER KENTUCKY WILL TRACK EAST THIS AFTERNOON AND
THEN MOVE SOUTHEAST ACROSS THE CAROLINAS TONIGHT AND OFF THE COAST
SUNDAY MORNING. THE LOW REMAINS OFFSHORE AS HIGH PRESSURE
GRADUALLY BUILDS IN FROM THE WEST FOR THE FIRST HALF OF THE WEEK.
ANOTHER LOW MAY IMPACT THE REGION FOR THE LATTER HALF OF THE WEEK.

&&

.NEAR TERM /THROUGH SUNDAY/...
FOR REST OF THIS AFTERNOON...AT 1830Z RADAR SHOWING SOME SCATTERED
RETURNS OVER LOWER SRN MD...BUT THE REMAINDER OF THE CWA WAS
CLOUDY BUT PRECIP FREE MOSTLY. LEADING EDGE OF PRECIP ALONG AN
ELKINS-STAUNTON VA-CHARLOTTESVILLE LINE. THIS AREA IS MOVING EAST
AT A PRETTY GOOD CLIP...AND WILL OVERSPREAD THE REGION IN THE NEXT
2-4 HOURS...EXCEPT NE MD COULD TAKE UNTIL 7-8PM FOR PRECIP TO START.

LOW LEVELS STILL QUITE DRY ACROSS NRN 2/3RDS OF CWA. PRECIP
REACHING SURFACE WILL CREATE LOW LEVEL COOLING...SO TEMPS WILL
KEEP ON THE COOL SIDE REMAINDER OF THIS AFTERNOON ESPECIALLY FOR
THIS LATE IN APRIL.

FOR TONIGHT...PRECIP ASSOCIATED WITH WARM FRONTAL SYSTEM LIFTING
ACROSS THE REGION WILL IMPACT THE REGION MAINLY THROUGH 06Z...THEN
MODELS SUGGEST BULK OF PRECIP WILL LIGHTEN CONSIDERABLY AFTER
THEN. EARLIER TIMING OF PRECIP SUGGESTED LINGERING LIGHT PRECIP
WOULD IMPACT ENTIRE CWA THROUGH 10-12Z SUNDAY MORNING. BUT
GUIDANCE TODAY SUGGESTS A FASTER TIMING WHICH IS REFLECTED IN THE
FORECAST. TEMPERATURES WILL NOT FALL MUCH OVERNIGHT AND BASICALLY
TRENDED MIN TEMPS TO ADJUSTED MET GUIDANCE.

FORECAST RAINFALL AMOUNTS GENERALLY LINE UP PRETTY WELL WITH WPC
QPF AMOUNTS AND WILL BE GENERALLY HEAVIER ACROSS THE SW PORTION
WITH AMOUNTS AROUND ONE HALF INCH...DC METRO AROUND ONE- QUARTER
OF AN INCH...BALTIMORE BETWEEN 1-2 TENTHS.

HI RES CAM MODELS SHOW GOOD AGREEMENT WITH 12Z NAM/GFS/SREF ON
TIMING OF PRECIP ACROSS AREA. LATEST HRRR GUIDANCE SUGGEST THE
PRECIP COULD EVEN BE MORE SCATTERED IN COVERAGE THIS EVENING.

FOR SUNDAY...THERE COULD BE LINGERING LIGHT PRECIP ACROSS THE SRN
TIER OF THE CWA JUST AFTER 12Z...BUT CLOUDS AND PRECIP WILL PUSH
SOUTH AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE GREAT
LAKES. HIGH TEMPS STILL COOL FOR THIS TIME OF YEAR...AND USED A
BLEND OF MOS/ADJ MAV.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
REGION REMAINS POSITIONED UNDER UPPER LVL LOW CENTERED OVER THE
CANADIAN MARITIMES WHILE SFC LOW SETTLES WELL OFFSHORE TO START
THE WORK WEEK. GENERALLY EXPECTING DRY CONDITIONS SUN NIGHT WITH A
BREAK IN THE SHORTWAVE ENERGY...THOUGH A SFC TROF COULD GENERATE
ISO SHOWERS SECOND HALF OF THE NIGHT. TEMPS DROPPING INTO THE 30S
FOR LOWS SUN NIGHT COULD RESULT IN ANY PCPN NEAR DAYBREAK BEING A
RAIN/SNOW OR EVEN ALL SNOW...WITH LITTLE TO NO ACCUM.

THE REGION WILL BE SANDWICHED BETWEEN HIGH PRESSURE OVER THE GREAT
LAKES AND THE LOW OFFSHORE MONDAY...RESULTING IN ELEVATED
WINDS...WITH GUSTS 25-30 MPH. POPS INCREASE AFTR 12Z MON AS NEXT
SHORTWAVE/VORT MAX ROUNDS THE LOW...WITH THE BETTER CHC WESTERN AND
EASTERN FRINGES OF THE CWA. THE STRONG SHORTWAVE WILL EXTEND ACROSS
THE MID ATLANTIC FOR MOST OF THE DAY...PRODUCING SCT SHOWERS.

PCPN TAPERS OFF MON EVENING AS UPPER LVL LOW PIVOTS OFFSHORE. AS THE
HIGH BUILDS IN...EXPECTING TO SEE WARMING TEMPS...WITH TEMPS NEARING
NORMAL BY MON NIGHT.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
DESPITE THE COOL START AND CONTINUED CAA BEHIND THE COLD
FRONT...TEMPS WILL REBOUND A FEW DEGREES TUE AS DECREASING CLOUDS
ALLOW THE LATE APRIL SUN TO DO ITS WORK. THIS SLOW WARMING TREND
CONTINUES INTO WED...WITH TEMPS BACK TO NEAR NORMAL...AS A WEAK AREA
OF HIGH PRESSURE BUILDS IN.

MODEL DIVERGENCE INCREASES SUBSTANTIALLY BY LATE WED INTO THU WITH
REGARDS TO DEVELOPING LOW OVER GOM. LATEST MODEL GUIDANCE APPEARS TO
SHUNT MAIN IMPACTS TO OUR SOUTH...WITH LITTLE QPF OVER CWA. 12Z GFS
FAR DIFFERENT FROM 00Z ECMWF...AS GFS HAS NO COASTAL LOW OFF THE
CAROLINA COAST AND ECMWF DOES. HAVE LOWERED POPS SOME FOR
THU...ALTHOUGH FOR CONSISTENCY AND TO AVOID JUMPING ON ONE MODEL
CYCLE STILL KEPT CHC POPS...ALTHOUGH THAT MIGHT BE TOO HIGH.

HIGH PRESSURE RETURNS BY FRIDAY...BRINGING NEAR NORMAL TEMPS.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
EXPECT VFR CONDITIONS THROUGH MID TO LATE DAY. PRECIP
WILL MOVE IN AND CIGS WILL LOWER. THIS EVENING EXPECT MVFR TO
LOCALLY IFR CIGS IN PRECIP...EXPECT BWI/IAD/DCA CIGS TO RANGE FROM
2-3 KFT THIS EVENING...LOCALLY DOWN TO 1KFT IN HEAVIER PRECIP.
OVERNIGHT...BWI AND IAD COULD SEE CIGS BLO 1KFT. WINDS WILL BE
UNDER 10 KTS THROUGH THE PERIOD.

VFR CONDITIONS SUN-SUN NIGHT. SUB-VFR CONDITIONS PSBL MON WITH ANY
RAIN SHOWER. GUSTY NW WINDS WITH GUSTS 20-25 KTS PSBL AS WELL
DURING THE DAY MON...DIMINISHING AFTR SUNSET. MVFR CIGS MAY LINGER
THRU MON NIGHT.

NOT EXPECTING AVIATION CONCERNS TUE/WED WITH VFR CONDITIONS.

&&

.MARINE...
WINDS EXPECTED TO BE BELOW 10 KTS ACROSS THE WATERS TODAY AND
VARIABLE IN DIRECTION. RAIN WILL OVERSPREAD THE WATERS THIS
AFTERNOON INTO THIS EVENING. WINDS REMAIN LESS THAN 10 KTS THROUGH
SUN MORNING...INCREASING SUN AFTN. GUSTS COULD BRIEFLY TOUCH 18-20
KTS SUN AFTN WITH NORTHERLY CHANNELING.

SUB-SCA CONDITIONS INITIALLY SUN EVENING...WITH INCRSG
WINDS OVERNIGHT. SCA CONDITIONS WITH GUSTS UP TO 20 KTS AS EARLY AS
THE SECOND HALF OF SUN NIGHT...BCMG MORE LIKELY AFTR DAYBREAK MON.
GUSTS UP TO 30 KTS PSBL ON THE CHESAPEAKE BAY DURING THE DAY. SCA
GUSTS CONTINUE THRU MON NIGHT.

SCA IS POSSIBLE TUE UNTIL THE PRESSURE GRADIENT WEAKENS WITH
DEPARTING LOW. PRESSURE GRADIENT RELAXES ENOUGH FOR A RETURN TO
LIGHT WINDS BY WED.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...SMZ
NEAR TERM...SMZ
SHORT TERM...SEARS
LONG TERM...MSE
AVIATION...SEARS/MSE/SMZ
MARINE...SEARS/MSE/SMZ



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.