Flash Flood Warning 17, NWS Baltimore/Washington

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON
340 PM EDT FRI JUN 22 2001

AT 18Z...SEVERAL TSTMS MAINLY BLUE RIDGE W PRODUCING VERY HEAVY
RAINFALL...HAIL...AND POSSIBLY STRONG WINDS.  STORMS SEEM TO
REDEVELOP OVER SAME AREAS WHICH ADDS TO FLOODING THREAT. TSTMS AND
SHRA WILL CONTINUE THROUGH NIGHT DUE TO APPROACHING FRONTAL
BDRY...STRONG UL DIVERGENCE...PLENTY OF VVEL AT 700 AND 500MB IN
ADDITION TO 850MB LOW MOVING OVHD.  WILL HAVE 80 POPS CWA WIDE. WILL
ALSO CONTINUE FLASH FLOOD WATCH UNTIL 4 AM FOR BLUE RIDGE W AND CHO
AREA. EXPECT HAIL/WIND THREAT TO DIMINISH A FEW HOURS AFT SUNSET DUE
TO LOSS OF DAYTIME HEATING BUT HVY RAIN WILL PROBABLY CONTINUE TO BE
A PROBLEM BECAUSE PRECIP H20 VALUES REMAIN AROUND 1.75 IN. MOST CWA
UNDER SVR TSTM WATCH THRU 7PM.

FRONT REACHES NW CWA BY MIDDAY BUT DOESNT REACH FAR SE CWA UNTIL
SUN MORNING. RELATIVELY DRIER AIR WILL COME IN BEHIND FRONT AND SHUD
GIVE US A RAIN FREE PERIOD FROM W TO E SUN MORN THRU MON AFT. UL LOW
CUTS OFF OVER SE US AND RETROGRADES A BIT MON INTO TUE. THIS TURNS
WINDS E FOR A TIME MON AND BRINGS IN SOME RH OFF THE WATER AND ALSO
SPINS SOME WEAK IMPULSES FROM S TO N THRU CWA. THIS WILL GIVE ATMOS
SOME RH AND LIFT TO WORK WITH...ESPECIALLY MON AFT...TO CREATE
WIDELY SCT SHRA/-TSRA. ATMOS WONT CHANGE SIG TUE SO WILL KEEP 30
POP FOR AFT CONVECTION IN FCST. HI PRES OVER THE OCEAN STARTS TO
INFLUENCE MID ATLANTIC WEATHER WED THRU FRI SO WILL FCST DRY COND.

REGARDING TEMPS...THOUGHT FWC LOW TEMPS WERE TOO COLD NEXT FEW NIGHT
DUE TO ELEVATED DEW PTS. STAYED NEAR GUIDANCE REST OF FCST.

FCSTID = 36
DCA   70  80  65  82 /  80  70  50  30
BWI   70  80  65  82 /  80  70  50  30
MRB   68  77  64  83 /  80  60  40  20
IAD   69  79  62  82 /  80  70  50  30
CHO   69  79  65  81 /  80  70  50  30
HGR   66  75  63  80 /  80  60  40  20
NHK   71  80  68  81 /  80  70  50  30

.LWX...
DC...NONE.
MD...FLASH FLOOD WATCH THRU 400 AM FOR ZONES MDZ002>003.

VA...FLASH FLOOD WATCH THRU 400 AM FOR ZONES VAZ021...VAZ025>031...
VAZ036>040...VAZ050>051.

WV...FLASH FLOOD WATCH THRU 400 AM FOR ZONES WVZ048>055.

MMARGRAF

DCZ001-MDZ002>007-009>011-013-014-016>018-VAZ021-025>031-036>042-
050>057-WVZ048>055-222100-

SEVERE WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BALTIMORE-WASHINGTON
1125 AM EDT FRI JUN 22 2001

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING ACROSS THE EASTERN WEST VIRGINIA PANHANDLE...NORTHERN
VIRGINIA...THE SHENANDOAH VALLEY...MUCH OF MARYLAND WEST OF THE
CHESAPEAKE BAY AND THE DISTRICT OF COLUMBIA.

WARM...MOIST AND UNSTABLE AIR COMBINED WITH A COLD FRONT APPROACHING
FROM THE WEST WILL RESULT IN THE DEVELOPMENT OF THUNDERSTORMS ACROSS
THE REGION THIS AFTERNOON AND EVENING.  SOME THUNDERSTORMS COULD
CONTAIN DAMAGING WINDS IN EXCESS OF 60 MPH AND HAIL UP TO AN INCH IN
DIAMETER. IN ADDITION...HEAVY RAINFALL FROM THUNDERSTORMS MAY RESULT
IN LOCALIZED FLOODING...ESPECIALLY IN LOW LYING AND POOR DRAINAGE
AREAS. HEAVY DOWNPOURS PRODUCE PONDING OF WATER ON ROADWAYS AND CAN
CAUSE SMALL STREAMS AND CREEKS TO OVERFLOW THEIR BANKS.

REMEMBER...ALL THUNDERSTORMS PRODUCE LIGHTNING. LIGHTNING CAN OCCUR
WITHOUT WARNING WELL IN ADVANCE OF RAINFALL ASSOCIATED WITH A
THUNDERSTORM. IF YOU CAN HEAR THUNDER...TAKE SHELTER IMMEDIATELY.

STAY TUNED TO NOAA WEATHER RADIO OR OTHER LOCAL MEDIA FOR UPDATES ON
THE SEVERE WEATHER THREAT AND POSSIBLE WATCHES AND WARNINGS THIS
AFTERNOON AND TONIGHT.

MMARGRAF