AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 950 PM EDT MON APR 18 2011 .SYNOPSIS... A WARM FRONT IS POSITIONED OVER SOUTHERN PENNSYLVANIA. THIS WILL STAY NEAR THE MASON-DIXON LINE THROUGH TUESDAY BEFORE TRACKING NORTH TUESDAY NIGHT. A COLD FRONT WILL MOVE ACROSS THE MID-ATLANTIC WEDNESDAY AND WEDNESDAY NIGHT...POSSIBLY BRINGING SHOWERS AND THUNDERSTORMS TO THE AREA. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT THURSDAY BEFORE MOVING OFF THE COAST LATE IN THE WEEK. && .NEAR TERM /THROUGH TUESDAY/... HV DONE A FURTHER CUT BACK TO POPS FOR TNGT AND THE 1ST PART OF TUE. SFC ANLYS SHOWS A LONG BNDRY STRETCHING FM TX TO THE DELMARVA. TO STEP OUTSIDE IT DEFINITELY FEELS LIKE WE`RE ON THE S SIDE OF A WARM FNT W/ SRLY WINDS..WARM TEMPS..AND MID/HIGH CLDS. CSTL FLD WRNG RMNS UP FOR DC/ALEX OVRNGT. HIGH TIDE IS UPON US AS THIS IS WRITTEN. THE 8 PM READING AT WASH HARBOR WAS JUST UNDER 9 FT (FLD STAGE IS 7). IT WL LKLY PEAK ARND 10 FT. BUT IN GOOD NEWS LTL FALLS HAS CRESTED SO LVLS AT WASH HARBOR/ALEX SHOULD BE FALLING ON TUE. PRVS DSCN... BOUNDARY REMAINS STATIONARY THROUGH TUESDAY. ANOTHER SHORTWAVE MOVES EAST DURING THE AFTERNOON...AND WILL INCREASE THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS TUESDAY AFTERNOON. FOR RIGHT NOW...THE BEST CHANCES LOOK TO BE NORTH AND WEST OF THE METRO AREAS. TOOK BLEND OF TEMPS. && .SHORT TERM /TUESDAY NIGHT/... SURFACE LOW PRESSURE OVER THE MIDWEST TUESDAY EVENING WILL MOVE THROUGH INTO THE GREAT LAKES OVERNIGHT TUESDAY AND EVENTUALLY INTO SOUTHERN CANADA WEDNESDAY. A STATIONARY BOUNDARY NEAR THE MASON DIXON LINE TUESDAY EVENING WILL MOVE NORTH AS A WARM FRONT DURING THIS TIME. SCATTERED SHOWERS ARE POSSIBLE NEAR THE MASON DIXON LINE TUESDAY NIGHT. THE COLD FRONT ASSOCIATED WITH THE STORM SYSTEM WILL MOVE INTO THE REGION WEDNESDAY AFTERNOON. WARM AND BREEZY CONDITIONS ARE EXPECTED AHEAD OF THE FRONT. MAX TEMPS WEDNESDAY WILL BE IN THE 80S ACROSS MOST LOCATIONS WITH SOUTHWEST WINDS FREQUENTLY GUSTING AROUND 30 TO 35 MPH. A WARM AND MOIST SOUTHWEST FLOW WILL CAUSE MODERATE AMOUNTS OF INSTABILITY AHEAD OF THE COLD FRONT. SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE ALONG AND AHEAD OF THE COLD FRONT ESPECIALLY DURING THE AFTERNOON HOURS. STRONG DEEP LAYER SHEAR PROFILES ALONG WITH MODERATE INSTABILITY INDICATES THAT THERE IS A POSSIBILITY OF SEVERE T-STORMS WITH DAMAGING WINDS AND HAIL THE PRIMARY THREAT. WILL CONTINUE TO MONITOR OVER THE NEXT COUPLE DAYS. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... ANY LEFTOVER CONVECTION WEDNESDAY EVENING ACROSS THE EASTERN PORTION OF THE CWA WILL MOVE OFF THE COAST ALONG WITH THE COLD FRONT. HIGH PRESSURE WILL BUILD OVERHEAD WEDNESDAY NIGHT THROUGH THURSDAY...BRINGING DRY AND COOLER CONDITIONS. HIGH PRESSURE WILL MOVE OFF THE COAST LATE IN THE WEEK. AN ONSHORE FLOW WILL USHER IN MORE MOISTURE FROM THE ATLANTIC OCEAN WHILE LOW PRESSURE PASSES BY TO OUR NORTH. RAIN IS POSSIBLE THURSDAY NIGHT AND FRIDAY. A WARM FRONT STALL OUT NEAR THE REGION DURING THE WEEKEND INTO EARLY NEXT WEEK WHILE A SERIES OF UPPER-LEVEL DISTURBANCES PASS BY TO OUR NORTH. UNSETTLED CONDITIONS ARE POSSIBLE DURING THIS TIME. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... VFR CONDS XPCTD OVRNGT. A STATIONARY FRONT WILL SETUP ALONG THE VA/MD/WV BORDER CAUSING WINDS TO SHIFT TO EASTERLY AT BWI AND MTN THROUGH TOMORROW MORNING. OVERNIGHT...WINDS WILL DIMINISH TO 5 TO 10 KT. VFR CONDITIONS ARE EXPECTED TUESDAY NIGHT INTO WEDNESDAY. A COLD FRONT WILL PASS THROUGH WEDNESDAY AFTERNOON WITH POSSIBLE SHOWERS AND T-STORMS. SOME T-STORMS MAY BECOME SEVERE. HIGH PRESSURE WILL RETURN THURSDAY BEFORE AN ONSHORE FLOW INCREASES THURSDAY NIGHT AND FRIDAY REDUCING CIGS AND VSBYS. && .MARINE... WINDS ACROSS THE WATERS HAVE BEGUN TO PICK UP OUT OF THE SE...AND GUSTS TO AROUND 20 KTS ARE BEING REPORTED ACROSS THE MID BAY. WINDS WILL SHIFT MORE S/SW OVERNIGHT AND CHANNEL UP THE BAY...CONTINUING THROUGH TOMORROW. NO CHANGES TO THE HEADLINES THIS AFTERNOON. A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE WATERS EARLY TUESDAY EVENING...AND FOR THE CHESAPEAKE BAY SOUTH OF NORTH BEACH AS WELL AS THE LOWER TIDAL POTOMAC RIVER TUESDAY NIGHT. A COLD FRONT WILL PASS THROUGH THE WATERS WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING. A SMALL CRAFT ADVISORY MAY BE NEEDED WEDNESDAY AHEAD OF THE FRONT AND ALSO FOR WEDNESDAY NIGHT AND THURSDAY BEHIND THE FRONT. AN ONSHORE FLOW WILL BRING UNSETTLED CONDITIONS THURSDAY NIGHT AND FRIDAY. SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE WEDNESDAY AFTERNOON AND EVENING AHEAD OF THE FRONT. DAMAGING WINDS AND LARGE HAIL ARE POSSIBLE IN SOME OF THE STRONGER T-STORMS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...COASTAL FLOOD WARNING UNTIL NOON EDT TUESDAY FOR DCZ001. MD...NONE. VA...COASTAL FLOOD WARNING UNTIL NOON EDT TUESDAY FOR VAZ054. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT TUESDAY FOR ANZ531-532-539- 540. SMALL CRAFT ADVISORY FROM NOON TO 8 PM EDT TUESDAY FOR ANZ530- 535-536-538. SMALL CRAFT ADVISORY FROM NOON TUESDAY TO 6 AM EDT WEDNESDAY FOR ANZ542. SMALL CRAFT ADVISORY UNTIL 6 AM EDT WEDNESDAY FOR ANZ533-534- 537-541-543. && $$ UPDATE...WOODY!