Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 011446
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1046 AM EDT SAT AUG 1 2015

.SYNOPSIS...
A WEAKENING COLD FRONT WILL CROSS THE REGION TODAY. HIGH PRESSURE
WILL REBUILD OVERHEAD SUNDAY BEFORE MOVING OFF THE COAST EARLY
NEXT WEEK. ANOTHER COLD FRONT WILL APPROACH FROM THE NORTHWEST
MONDAY AND THEN IT WILL STALL OUT NEARBY FOR TUESDAY AND
WEDNESDAY. LOW PRESSURE MAY RIDE ALONG THE BOUNDARY...PASSING
THROUGH OUR AREA THURSDAY AND THE BOUNDARY WILL SHIFT TO THE SOUTH
LATE IN THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
APPROACHING COLD FRONT HAS JUST ABOUT WASHED OUT AND MOST RECENT
ANALYSIS FROM WPC INDICATES ONLY A COUPLE OF SURFACE TROUGHS IN
ITS PLACE. DEW POINTS ARE A BIT ELEVATED COMPARED TO YESTERDAY
HOWEVER...AND A WEAK TROUGH IS MOVING THROUGH ALOFT...SO THE NAM
DEPICTION OF A FEW SHOWERS THIS AFTERNOON IS NOT COMPLETELY
IMPOSSIBLE. FOR THE TIME BEING HOWEVER...GIVEN ITS MORE OR LESS
OUT ON ITS OWN...HAVE KEPT POPS BELOW 15 PERCENT. AFTERNOON HIGH
TEMPERATURES ARE EXPECTED TO TOP OUT IN THE UPPER 70S TO LOW 80S
WEST OF THE BLUE RIDGE...MID TO UPPER 80S EAST OF THE BLUE
RIDGE...EXCEPT NEAR 90 OVER THE BALTIMORE AND WASHINGTON DC METRO
AREAS. OVERNIGHT LOWS WILL DIP BACK INTO THE 60S...EXCEPT LOW 70S
IN THE METRO AREAS. SOME PATCHY FOG COULD DEVELOP OVERNIGHT MAINLY
INLAND AWAY FROM THE METRO.

&&

.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
HIGH PRESSURE WILL BUILD OVER THE REGION ON SUNDAY. AFTERNOON
HIGH TEMPERATURES WILL LIKELY REACH INTO THE UPPER 80S TO THE
LOWER 90S...WARMEST OVER THE DC/BALTIMORE METRO AREAS.

HIGH PRESSURE WILL WEAKEN OVER THE AREA SUNDAY NIGHT...BUT IT
SHOULD CONTINUE TO BRING DRY CONDITIONS TO THE AREA. MIN TEMPS
WILL RANGE FROM THE 50S AND 60S IN THE POTOMAC HIGHLANDS TO THE
LOWER AND MIDDLE 70S IN DOWNTOWN WASHINGTON/BALTIMORE. POTENTIAL
OF PATCHY FOG ONCE AGAIN AWAY FROM THE WATER AND METRO AREAS.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
A WEAK COLD FRONT WILL PASS THROUGH THE AREA MONDAY AFTERNOON AND
EVENING. HOWEVER...IT WILL ACTUALLY TURN OUT HOTTER MONDAY DUE TO
PLENTY OF SUNSHINE AND A DOWNSLOPING WESTERLY COMPONENT TO THE
SURFACE FLOW. MAX TEMPS WILL BE IN THE LOWER TO MIDDLE 90S ACROSS
MOST AREAS. DEWPOINTS SHOULD REMAIN IN THE 50S AND LOWER 60S FOR
MOST AREAS...KEEPING RELATIVE HUMIDITY DOWN WHICH SHOULD ALLOW FOR
HEAT INDICES TO BE NEAR THE AIR TEMPERATURES. AN ISOLATED SHOWER
OR THUNDERSTORM CANNOT BE RULED OUT...BUT MOST AREAS WILL TURN OUT
DRY.

WEAK HIGH PRESSURE WILL BUILD OVERHEAD MONDAY NIGHT...BRINGING DRY
CONDITIONS.

AN UPPER-LEVEL LOW WILL CONTINUE TO SPIN NEAR THE HUDSON BAY
TUESDAY THROUGH FRIDAY WHILE AN UPPER-LEVEL RIDGE REMAINS CENTERED
ACROSS THE SOUTH-CENTRAL CONUS ACROSS FLORIDA INTO THE ATLANTIC
OCEAN. A ZONAL FLOW IS EXPECTED OVERHEAD DURING THIS TIME. A
NEARLY STATIONARY BOUNDARY WILL SEPARATE THE TWO AIRMASSES BETWEEN
COOL CONDITIONS ACROSS THE NORTHEASTERN CONUS AND HOT AND HUMID
CONDITIONS ACROSS THE SOUTHEASTERN CONUS. THERE IS STILL SOME
UNCERTAINTY AS TO WHERE EXACTLY THIS BOUNDARY WILL SETUP...BUT
LATEST GUIDANCE KEEPS IT NEAR THE MASON-DIXON LINE THROUGH THE
MIDDLE PORTION OF NEXT WEEK BEFORE THE BOUNDARY POSSIBLY SLIDING
SOUTH LATE IN THE WEEK.

IF THE BOUNDARY REMAINS TO OUR NORTH...THEN UNSETTLED CONDITIONS
ARE POSSIBLE DUE TO THE WARM AND HUMID CONDITIONS OVERHEAD ALONG
WITH DISTURBANCES IN THE ZONAL FLOW ALOFT. HOWEVER...IF THE
BOUNDARY IS FARTHER SOUTH...THEN COOL AND LESS HUMID CONDITIONS
WILL KEEP UNSETTLED WEATHER TO OUR SOUTH. AS OF NOW...THE FORECAST
LEANS TOWARD THE FIRST SCENARIO WHICH IS IN AGREEMENT WITH MOST OF
THE GUIDANCE. HOWEVER...THERE IS STILL UNCERTAINTY WITH THE MODEL
FORECASTS DURING THIS TIME FRAME. A STRONGER UPPER-LEVEL
DISTURBANCE/SURFACE LOW MAY ENHANCE THE THREAT FOR CONVECTION
WEDNESDAY NIGHT THROUGH THURSDAY IF THE BOUNDARY IS FARTHER NORTH
NEAR THE MASON-DIXON LINE.

&&

.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS EXPECTED TODAY THROUGH SUNDAY. SOME PATCHY FOG
COULD DEVELOP IN SPOTS OVERNIGHT INTO EARLY SUNDAY BUT CONFIDENCE
IN DIRECT IMPACT TO ANY TERMINAL IS LOW AND MENTION WILL BE KEPT
OUT OF THE TAFS AT THIS TIME.

HIGH PRESSURE WILL ALLOW FOR DRY CONDITIONS SUNDAY NIGHT. AGAIN
POTENTIAL FOR PATCHY FOG INLAND AND AWAY FROM METRO AREA. A WEAK
COLD FRONT MAY TRIGGER AN ISOLATED THUNDERSTORM MONDAY...BUT MOST
AREAS WILL BE DRY. AN ISOLATED SHOWER/THUNDERSTORM IS POSSIBLE
TUESDAY...BUT AGAIN MOST AREAS WILL END UP DRY. THERE MAY BE A
BETTER CHANCE FOR SHOWERS AND THUNDERSTORMS DURING THE MIDDLE
PORTION OF NEXT WEEK.

&&

.MARINE...
WINDS WILL BE CLOSE TO SCA THIS AFTERNOON WITH TROUGH MOVING
ACROSS THE AREA BUT THINK IT WILL STAY JUST BELOW CRITERIA. WINDS
SHOULD STAY WELL BELOW SCA SUNDAY.

HIGH PRESSURE WILL REMAIN NEAR THE WATERS SUNDAY NIGHT. A WEAK
COLD FRONT WILL PASS THROUGH THE WATERS LATE MONDAY INTO MONDAY
NIGHT. SOUTHWEST WINDS AHEAD OF THE BOUNDARY MAY GUST AROUND SCA
CRITERIA AHEAD OF THE FRONT MONDAY AFTERNOON AND EVENING. WESTERLY
WINDS BEHIND THE BOUNDARY MAY GUST NEAR SCA CRITERIA OVERNIGHT
MONDAY.

A STATIONARY BOUNDARY WILL SETUP NEAR THE WATERS DURING THE MIDDLE
PORTION OF NEXT WEEK...AND UNSETTLED CONDITIONS ARE POSSIBLE
DURING THIS TIME.

&&

.TIDES/COASTAL FLOODING...
FULL MOON WILL CAUSE ASTRONOMICALLY HIGH
TIDES TODAY. WHILE TIDES WILL BE SLIGHTLY ABOVE NORMAL...AM NOT
EXPECTING ANY FLOODING.

&&

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

&&

$$
SYNOPSIS...BJL/RCM
NEAR TERM...KRW/RCM
SHORT TERM...BJL/KRW/RCM
LONG TERM...BJL
AVIATION...BJL/KRW/RCM
MARINE...BJL/KRW/RCM
TIDES/COASTAL FLOODING...



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