Severe Thunderstorm Warning 102, NWS Baltimore/Washington

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON
235 PM EDT THU JUL 5 2001

PATTERN ACRS THE COUNTRY WILL BE DOMINATED BY AN UPR LVL TROF OVR
THE ERN U.S. AND UPR LVL RDG OVR THE ROCKIES AND PLAIN STATES. BY
SAT...THE UPR LVL TROF WILL BEGIN TO LIFT OUT AS THE CUTOFF LOW OVR
QUEBEC BEGINS TO MOVE NE. THIS WILL RESULT IN RISING HGTS OVR THE
AREA BY SAT. HOWEVER...BY SUN...ANOTHER PIECE OF ENERGY DROPS INTO
THE LONGWAVE TROF POSITION ALG THE E COAST...REINFORCING THE TROF.

SFC CDFNT WILL MOVE THRU THE AREA THIS EVE. DON'T EXPECT WIDESPREAD
CONVECTION ALG OR AHD OF THE CDFNT. SOUNDINGS SHOW A WEAK CAP OVR
THE AREA. WINDS WILL NOT BE BACKING MUCH AHD OF THE CDFNT SO
CONVERGENCE IS WEAK.  IN ADDITION...ALL THE DEEP MOISTURE HAS BEEN
SWEPT E OF THE AREA WITH THE SFC TROF LEAVING ONLY SOME RESIDUAL
SHALLOW MOISTURE OVR THE AREA. ALSO...WESTERLY FLOW AHD OF THE CDFNT
WILL RESULT IN DOWNSLOPING WHICH WILL TEND TO SUPPRESS CONVECTION.
HOWEVER...MODIFIED SOUNDING SHOWS A CAPE OF 1300 THIS EVE WITH LIS
AROUND MINUS 4. IN ADDITION...THE 12Z ETA AND NGM BOTH SHOW SOME QPF
OVR THE AREA. WILL LEAVE 30 POPS IN THE FCST UNTIL MIDNIGHT THEN P/C.

SFC HIGH PRES BUILDS INTO THE AREA FRI AND FRI NIGHT WITH A COOL AND
DRY AIR MASS. GOING WITH SUNNY SKIES FRI AND CLR FRI NIGHT.

SFC HIGH MOVES OFF THE CST SAT AND RETURN S FLOW DEVELOPS BRINGING
SOME MOISTURE BACK INTO THE AREA. IN ADDITION...AS HGTS START TO
RISE OVR THE AREA...WHATS LEFT OF THE FNT TO OUR S WILL MOVE BACK N
AS A WEAK WMFNT. ETA DEVELOPS SOME UVVS OVR THE AREA LATE SAT IN
ASSOCIATION WITH THE RETURN FLOW/WMFNT. THE AVN KEEPS THE UVVS NW OF
THE AREA. THINK THE ETA MAY BE OVERDOING THE UVVS AND MOISTURE SO
RIGHT NOW WILL ONLY HAVE HIDDEN 20 POPS IN FOR SAT AND HOLD OFF ON
MENTIONING ANY SHRAS/TSRAS UNTIL SAT NIGHT.

NGM AND AVN MOS NUMBERS ARE CLOSE THE 1ST 3 PDS. HOWEVER...THE MOS
HAS BEEN RUNNING TOO WARM LATELY WHEN WE GET A COOL DRY AIR MASS
INTO THE AREA. WILL UNDERCUT MOS TEMPS A COUPLE DEGREES ON FRI.  NGM
MOS IS WARMER THAN THE AVN MOS FOR SAT. WENT WITH A COMPROMISE
BETWEEN THE TWO SETS OF NUMBERS SAT.

FOR THE EXTENDED...
THE AVN HAS A CDFNT MOVING THRU THE AREA ON SUN AS THE NEXT
SHORTWAVE DROPS INTO THE TROF POSITION. WILL HAVE CHC POPS SUN FOR
SHRA/TSRA. HIGH PRES BUILDS INTO THE AREA MON/TUE WITH DRIER AIR
MASS.

FCSTID = 15 / DMW

DCA   63  81  63  87 /  30   0   0  20
BWI   58  80  56  87 /  30   0   0  20
MRB   54  80  52  87 /  30   0   0  20
IAD   54  80  52  87 /  30   0   0  20
CHO   58  81  59  87 /  30   0   0  20
HGR   52  79  51  86 /  30   0   0  20
NHK   6U4  81  63  87 /  30   0   0  20
W99   48  78  47  85 /  30   0   0  20

.LWX...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.