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 291855
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
255 PM EDT FRI MAY 29 2015

.SYNOPSIS...

HIGH PRESSURE WILL REMAIN OFFSHORE TODAY. SOUTHERLY WINDS WILL
CONTINUE TO BRING WARM AND HUMID CONDITIONS TO THE MID-ATLANTIC
THROUGH SATURDAY. A COLD FRONT WILL ARRIVE SUNDAY AND STALL OVER
THE AREA THROUGH MONDAY. HIGH PRESSURE IS EXPECTED TO SLIDE INTO
THE REGION FOR THE MIDDLE PART OF NEXT WEEK.

&&

.NEAR TERM /TONIGHT/...

AS DSCD ERLR...MRNG SNDG SHOWED VERY LGT WINDS UP THRU THE
ATMOSPHERIC COLUMN WHICH WOULD LEND ITSELF TO STRAIGHT UP AND DOWN
CELLS WHICH WOULD HV THE PTNL TO PRODUCE HVY RA IN A SHORT TIME
WHERE CELLS POPPED UP. THIS IS WHAT WE`RE SEEING ON RDR ATTM...AND
XPCT THIS TO CONT TO BE THE SITUATION INTO THE EVE HRS.

AFTR THAT ANOTHER WARM NGT ON TAP FOR THE AREA. IN ERLR DSCN TDA I
WROTE THAT DC IS TIED FOR THE WARMEST MAY ON RECORD AND THE 2ND
WARMEST FOR MIN TEMPS.

LOWS TNGT GNRLY IN M60S..L70S IN THE CITIES.

&&

.SHORT TERM /SATURDAY/...

AREA RMNS IN THE SAME AIR MASS SAT - CD FNT RMNS TO OUR NW BUT IS
WORKING ITS WAY IN THIS DIRECTION. BEST CHC OF TSTMS WL BE IN THE
AFTN IN THE WRN PART OF THE CWA. HIGHS WL AGN BE IN THE MU80S.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...

ON SATURDAY NIGHT...THE UPPER LEVEL RIDGE OFFSHORE WILL BEGIN TO BE
SUPPRESSED BY A SHORTWAVE TROUGH PUSHING THROUGH CANADA. A COLD
FRONT WILL BE APPROACHING FROM THE NW...EXTENDING DOWN THE ST
LAWRENCE VALLEY INTO THE SOUTHER GREAT LAKES. AFTER ANY DIURNAL
CONVECTION SUBSIDES...A CHANCE OF SHOWERS WILL REMAIN NEAR THE PA
BORDER FOR ANY ACTIVITY THAT RACES AHEAD OF THE FRONT. OTHERWISE
JUST ANOTHER MUGGY NIGHT WITH INCREASING CLOUDS AND LOWS IN THE
60S...LOWER 70S URBAN AREAS.

CONFIDENCE IN THE SUNDAY TO SUNDAY NIGHT PERIOD IS NOT PARTICULARLY
HIGH AS THE COLD FRONT ADVANCES INTO THE AREA. THERE IS STILL SOME
MODEL SPREAD IN HOW QUICKLY THE FRONT WILL PUSH SOUTHWARD...BUT THE
OVERALL TREND HAS BEEN SLOWER. THIS MAKES SENSE BECAUSE THE FRONT
WILL BECOME PARALLEL TO THE UPPER FLOW AS IT PUSHES INTO THE STRONG
RIDGE. A WAVE OF LOW PRESSURE WILL ALSO MOVE ALONG THE FRONT
SOMETIME IN THIS TIME PERIOD. THUNDERSTORMS SEEM LIKE A GOOD
BET...BUT WILL NOT BE GOING HIGHER THAN LIKELY YET DUE TO THE TIMING
UNCERTAINTY. THIS ALSO MEANS HIGH TEMPS SUNDAY WILL LIKELY BE A BIT
HIGHER...AND COULD ONCE AGAIN APPROACH 90 OVER THE SE CWA WHICH WILL
HAVE FAIRLY LOW PRECIP CHANCES DURING MUCH OF THE DAY.

IT LOOKS LIKE ANY SEVERE POTENTIAL SUNDAY WILL BE LIMITED AND TIED
TO BUILDING INSTBY AS SHEAR WILL NOT BE PARTICULARLY STRONG. A
BIGGER THREAT MAY BE DUE TO HEAVY RAIN AND FLOODING DUE TO THE
STALLING FRONT...DEVELOPING LLJ SUNDAY NIGHT...AND FAVORABLE UPPER
DIVERGENCE IN A HIGH PWAT ENVIRONMENT. HOWEVER...A LITTLE DIFFICULT
TO SAY WHICH TIME PERIOD AND WHICH PART OF THE MID-ATLANTIC WOULD
HAVE THE BIGGEST THREAT AT THIS TIME.

A BIG SHIFT IN THE PATTERN WILL OCCUR BEHIND A COLD FRONT EARLY NEXT
WEEK. AS THE FRONT DROPS SLOWLY SOUTH...RAIN CHANCES WILL SLOWLY
DIMINISH MONDAY INTO TUESDAY. MEANWHILE...HIGH PRESSURE WILL BUILD
OVER NEW ENGLAND SETTING UP A COOL AIR DAMMING WEDGE ACROSS THE
REGION. TEMPERATURES WILL SHIFT FROM HEAT AND HUMIDITY MORE TYPICAL
OF MID-JULY TO TEMPERATURES MORE TYPICAL OF MID-APRIL.

AS THE HIGH GRADUALLY SHIFTS TO THE EAST AND WEAKENS...TEMPERATURES
WILL GRADUALLY REBOUND TO NEAR NORMAL LEVELS BY THE END OF THE WEEK.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...

ISOLD TSTMS WL BE THE MAIN CONCERN THRU ARND 02Z. IF ONE MOVES OVR
A TERMINAL XPCT BRIEF VERY HVY RAFL AND DIMINISHED VSBY. FOG PSBL
LATE TNGT AT CHO/IAD/MRB. THERE WL BE CHCS FOR TSTMS AGN SAT
AFTN...BEST CHC AT MRB.

TIMING OF COLD FRONT SUNDAY-SUNDAY NIGHT A BIT SLOWER...BUT
THUNDERSTORMS WILL STILL BE LIKELY AT SOME POINT DURING THE TIME
PERIOD. HEAVY RAIN POSSIBLE...SO IFR FLIGHT CONDITIONS MORE LIKELY
THAN THEY HAVE BEEN WITH RECENT SCATTERED STORMS.

NELY FLOW 10 KT OR SO MON-TUE. SUB-VFR PSBL IN LOW CIGS/-RA.
&&

.MARINE...

WINDS RMN BLO SCA VALUE THIS AFTN/TNGT. ISOLD TSTMS MAY IMPACT THE
WATERS THRU MID EVE. THESE COULD PRODUCE VERY HVY RAFL.

SRLY WINDS ARE XPCTD TO INCRS SAT AHD OF A CD FNT. AN SCA IS IN
EFFECT.

WINDS WILL DECREASE SOME SATURDAY NIGHT AND WILL KEEP SCA IN PLACE
AS ORIGINALLY ISSUED...WHICH WILL BE IN EFFECT FOR THE MAIN CHANNEL
OF THE BAY THROUGH THE NIGHT. SOUTHERLY FLOW ON SUNDAY MAY APPROACH
SCA CONDITIONS BUT WILL BE MARGINAL. COLD FRONT PASSAGE APPEARS IT
WILL BE A BIT SLOWER...BUT THUNDERSTORMS WILL STILL EVENTUALLY
BECOME LIKELY SUNDAY AFTERNOON/NIGHT AND POSE A LOCALIZED WIND
THREAT. GRADIENT WIND FIELD UNCERTAIN BY SUNDAY NIGHT AND WILL
DEPEND ON FRONTAL POSITION.

HIGH PRESSURE BUILDING IN BEHIND A COLD FRONT WILL LIKELY PUSH
NORTHEASTERLY WINDS TO SMALL CRAFT ADVISORY LEVELS MONDAY INTO
TUESDAY.

&&

.CLIMATE...

HOT TEMPERATURES WILL CONTINUE THROUGH SATURDAY...FOLLOWED BY WELL
BELOW NORMAL TEMPERATURES EARLY NEXT WEEK. BELOW IS A LIST OF RECORD
DAILY WARM TEMPERATURES FOR MAY 29TH AND 30TH.

.......RECORD WARM TEMPERATURES FOR DCA........
DATE...RECORD HIGH...........RECORD HIGH MIN...
5/29...97 (1991/1969)........74 (1991).........
5/30...98 (1991).............74 (1991).........

.......RECORD WARM TEMPERATURES FOR BWI........
DATE...RECORD HIGH...........RECORD HIGH MIN...
5/29...97 (1969).............71 (1908).........
5/30...98* (2011/1991).......72 (1895).........
*ALSO HIGHEST OBSERVED MAY MONTHLY TEMPERATURE

.......RECORD WARM TEMPERATURES FOR IAD........
DATE...RECORD HIGH...........RECORD HIGH MIN...
5/29...97* (1969)............69 (2012).........
5/30...95 (2006/1991/1987)...70 (2011).........
*ALSO HIGHEST OBSERVED MAY MONTHLY TEMPERATURE

BELOW IS THE LONGEST STRETCH OF CONSECUTIVE DAYS AT OR ABOVE 90 F
DURING THE MONTH OF MAY.

DCA...7 DAYS (05/25-05/31/1991)
BWI...7 DAYS (05/25-05/31/1991)
IAD...7 DAYS (05/25-05/31/1991)

BWI HIT 91 DEGREES ON THURSDAY MAY 28TH. THIS WAS THEIR FIRST 90+
DEGREE DAY OF 2015 AND THE WARMEST SINCE SEPTEMBER 6TH 2014 (WHEN
THEY HIT 93 DEGREES).

BELOW IS A LIST OF RECORD DAILY LOW MAXIMUM TEMPERATURES FOR JUNE
1ST AND 2ND.

SITE...6/1..............6/2..............
DCA....54 (1907)........53 (1907)........
BWI....54 (1907)........53* (1907).......
IAD....63 (2001/1966)...64 (1974/1963)...
*ALSO RECORD DAILY LOW MAXIMUM TEMPERATURE FOR THE MONTH

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON SATURDAY TO 2 AM EDT SUNDAY FOR
     ANZ530-537>542.
     SMALL CRAFT ADVISORY FROM 10 AM SATURDAY TO 8 AM EDT SUNDAY
     FOR ANZ531>534-543.

&&

$$
PRODUCTS...WOODY!/ADS/DFH



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