Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KLWX 301431 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1031 AM EDT THU JUL 30 2015 .SYNOPSIS... A COLD FRONT WILL CROSS THE AREA THIS AFTERNOON WITH SHOWERS AND THUNDERSTORMS EXPECTED. HIGH PRESSURE BUILDS INTO THE AREA TONIGHT AND PERSISTS INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
14Z OBS AND VIS SAT INDICATING COLD FRONT CURRENTLY BACK OVER WESTERN PA STRETCHING INTO CENTRAL WV. REFLECTIVITY SHOWING LINE OF SHOWERS AHEAD OF THE FRONT OVER WESTERN MD WHERE THE INVERSION HAS WEAKEN ALREADY THIS MORNING...AND SBCAPE VALUES AROUND 1000 J/KG. 14Z HRRR CONTINUES THIS LINE EAST...WITH ANOTHER AREA FORMING TO THE SOUTH AND WEST...EVENTUALLY CONNECTING THE TWO OVER NORTHERN VA LATER THIS AFTN. EXCEPTIONAL SFC MOISTURE OVER THE AREA MAKES THE GREATEST RISK TODAY FLASH FLOODING FROM EXCESSIVE RAINFALL. ACTIVITY EXPECTED TO BE PROGRESSIVE...SO THIS THREAT IS ISOLATED AT BEST. THERE IS A MARGINAL SEVERE RISK EAST OF THE BLUE RIDGE WHERE DIURNAL TIMING OF ACTIVITY IS BEST (AFTERNOON). HOWEVER...DEEP MOISTURE JUST LIKE YESTERDAY WILL LIMIT MID LEVEL LAPSE RATES AND THE SEVERE THREAT. JUST A LOW WET MICROBURST THREAT WITH THE STRONGEST ACTIVITY. HOT TODAY WITH MAX TEMPS LOW 90S EAST OF THE BLUE RIDGE WHERE THICK CLOUDS SHOULD HOLD OUT THE LONGEST. DEWPOINTS IN THE LOW TO MID 70S WILL RESULT IN MAX HEAT INDICES AGAIN AROUND 100F (JUST LIKE PREVIOUS TWO DAYS). NO HEAT ADVISORY...BUT IT WILL BE UNCOMFORTABLE UNTIL THE STORMS HIT/FRONT CROSSES.
-- End Changed Discussion --
&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
-- Changed Discussion --
COLD FRONT CLEARS THE SERN ZONES THURSDAY EVENING WITH DRIER AIR TRAILING. DEWPOINTS DROP INTO THE UPR 50S/LOW 60S TONIGHT. MIN TEMPS 60S WEST OF I-95...LOW 70S EAST. FRIDAY...H85 TEMPS 16-18 WITH MAX TEMPS AROUND 90F. DEWPOINTS WILL BE DOWN AROUND 60F...SO NO HEAT INDEX IS EXPECTED. DRY.
-- End Changed Discussion --
&& .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
-- Changed Discussion --
WEAK HIGH PRESSURE BUILDS FRI NIGHT. A PRESSURE TROUGH ESTABLISHES SAT WITH SOME MOISTURE RETURN AND A SLIGHT CHANCE OF SHOWERS AND T-STORMS. SFC RIDGE BUILDS AGAIN SUN GIVING WAY TO A HOT SUNNY DAY. WINDS TURN SWRLY AGAIN ON MON AS PRESSURE TROUGH ESTABLISHES WITH SOME MOISTURE RETURN AND A RISK OF T-STORMS. A CDFNT PUSHES THROUGH THE AREA TUE WITH DRY NWRLY WINDS AND A COOLING TREND MID TO LATE NEXT WEEK AS HIGH PRES BUILDS OVER THE REGION. IN SUMMARY...HOT WX DURING THE WEEKEND AND EARLY NEXT WEEK THEN TURNING COOLER MID WEEK ON. PRECIP LOOKS TO BE BELOW NORMAL NEXT 7 DAYS.
-- End Changed Discussion --
&& .AVIATION /15Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
MAINLY VFR CONDITIONS FOR THE TAF PERIOD. SCT SHOWERS AND TSTMS WILL MOVE THRU THE TAF SITES THIS AFTN AHEAD OF AN APPROACHING COLD FRONT. ANY STORM COULD RESULT IN GUSTY...VRB WINDS AND HEAVY RAIN WHICH COULD REDUCE VIS TO IFR. ANY CONVECTION WILL EXIT TO THE EAST BY 02Z THIS EVENING...WITH VFR AND DRY CONDITIONS LASTING THRU FRIDAY. A SLIGHT RISK OF T-STORMS SAT AND MON. REST OF THE TIME LOOKS FINE WITH VFR CONDITIONS.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
SCA FOR ALL WATERS STARTING AT 3PM AND CONTINUING UNTIL LATE EVENING AS A WEAK COLD FRONT WITH HEAVY AND GUSTY THUNDERSTORMS CROSS. SCA CONTINUES FOR MAIN BAY WATERS FOR NWLY FLOW 15 TO 20 KT LATE TONIGHT. FLOW DECREASES TO 10 TO 15 KT FRIDAY. POSSIBLE SCA SATURDAY AFTERNOON. OTHERWISE...WINDS SHOULD REMAIN BELOW SCA MOST OF THE 5-DAY FCST PERIOD. A SLIGHT RISK OF T-STORMS SAT AND MON.
-- End Changed Discussion --
&& .LWX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 6 AM EDT FRIDAY FOR ANZ530>533-538>541. SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 10 PM EDT THIS EVENING FOR ANZ535-536-542. SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 8 AM EDT FRIDAY FOR ANZ534-537-543.
-- End Changed Discussion --
&& $$ SYNOPSIS...BAJ/LFR NEAR TERM...BAJ/SEARS SHORT TERM...BAJ LONG TERM...LFR AVIATION...BAJ/SEARS/LFR MARINE...BAJ/LFR

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