Severe Thunderstorm Warning 185, NWS Baltimore/Washington

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
258 PM EDT MON JUL 14 2014

.SYNOPSIS...
BERMUDA HIGH PRESSURE WILL KEEP VERY WARM AND HUMID CONDITIONS
ACROSS THE MID-ATLANTIC INTO TUESDAY. A COLD FRONT WILL CROSS THE
AREA TUESDAY NIGHT. CANADIAN HIGH PRESSURE WILL BUILD ACROSS THE
EASTERN STATES WEDNESDAY THROUGH THURSDAY NIGHT.

&&

.NEAR TERM /THROUGH TONIGHT/...
HOT AND HUMID ALL AROUND W/ TEMPS NOW IN THE UPPER 80S AND LOW 90S
NOW COVER THE REGION...W/ DEWPOINTS HOVERING IN THE L70S. HEAT
INDICES WILL TOP OUT IN THE M-U90S OVER THE NEXT FEW HRS...AS WE
REACH PEAK HEATING. A WEAK LEE TROUGH AXIS NOW DRIFTING ACROSS THE
BLUE RIDGE/SHEN VLY HAS HELPED TO KICK-OFF THE INITIAL TSTM
ACTIVITY. SHEAR PROFILES STILL RELATIVELY WEAK BUT AND LAPSE RATES
PROVING TO NOT BE SUFFICIENT FOR SEVERE UPDRAFTS HERE IN THE EARLY
AFTN...BUT THIS ACTIVITY IS EXPECTED TO BE ENHANCED AS THE
BOUNDARY LAYER CONTINUES TO WARM AND CELLS TRAVEL INTO A MORE
FAVORABLE ENVIRONMENT FURTHER EAST.

THE AREA STILL RESIDES UNDER THE BASE OF A LARGER UPPER TROUGH
BACK ACROSS THE GREAT LAKES...WHICH WILL SEND A MINOR SHORTWAVE
KINK IN THE UPPER FLOW TOWARD THE AREA IN THE COMING HRS. THIS
FEATURE WILL DEEPEN SLIGHTLY AS IT MOVES EWD AND CLOSER TO THE
COAST...BUT WILL BE MORE THAN ENOUGH TO BE OUR MAIN LIFTING
MECHANISM TODAY AS SCATTERED SHOWERS AND WEAK TSTMS NEAR THE
APLCNS FROM THE WEST. LOCAL GUIDANCE POINTS TOWARD A LEE SFC
TROUGH DRIFTING OVER THE APLCNS IN SHORT ORDER AND PRODUCING IT'S
OWN CONVECTION FROM THE NRN SHEN VLY AND EWD...FROM EARLY AFTN
ONWARD. AS THE SHORTWAVE TROUGH NEARS THE I-95 CORRIDOR/ERN
SEABOARD...THE LOW LEVEL SHEAR PARAMETERS WILL INCREASE LATER THIS
AFTN/EVE - GIVING ONGOING CONVECTION MORE ENERGY FOR ORGANIZATION
AND POTENTIALLY MESOVORTICES AND/OR TORNADO PRODUCTION. NERN MD
APPEARS TO THE BE MORE FAVORABLE LOCATION FOR THESE ELEMENTS TO
COME TOGETHER ACROSS OUR REGION...IN TERMS OF
INSTABILITY/SHEAR/TIMING.

LOCALIZED HEAVY RAIN ALSO POSSIBLE AND EXPECTED ACROSS ISOLATED
LOCATIONS THIS AFTN...SO THE POTENTIAL FOR FLASH FLOODING - ESPEC
IN URBAN AREAS - EXISTS BUT WILL DEPEND ON RESIDENCE TIME UNDER
THE HEAVIEST RAIN AND ANY POSSIBLE TRAINING. HOLDING OFF ON THE FF
WATCH BECAUSE OF THE ISOLATED POTENTIAL AND PROGRESSIVE NATURE OF
THE INCOMING CONVECTION. HOWEVER...THE RAINFALL FROM LAST NIGHT...
TODAY AND INTO TOMORROW WILL RAMP UP THE POTENTIAL FOR A FF WATCH
FOR PARTS OF THE AREA ON TUE. HWO WILL CONTINUE TO MENTION THESE
RISKS.

ORGANIZED CONVECTION/SEVERE RISK SHOULD DIMINISH/MOVE OUT OF THE
CWA THIS EVENING...BUT GENERALIZED BROAD LIFT CONTINUES ACROSS THE
CWA. NO AIRMASS CHANGE OVERNIGHT...SO EVEN WEAK CONVERGENCE WILL
DEVELOP LIGHT SHOWERS BUT ISOLATED.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
MOIST/UNSTABLE ENVIRONMENT PERSISTS OVER THE CWA ON TUESDAY...WITH
AN AXIS OF HIGH PRECIPITABLE WATER/THETA-E AIR EAST OF THE BLUE
RIDGE. SOME CONVECTION WILL LIKELY BE ONGOING TUESDAY MORNING...
INCREASING IN COVERAGE AGAIN FOR THE AFTERNOON AS A COLD FRONT
APPROACHES FROM THE WEST AND AS HEIGHTS LOWER IN ADVANCE OF AN
APPROACHING UPPER TROUGH.

SEVERE WEATHER /DAMAGING WIND GUSTS/ AND FLASH FLOODING WILL AGAIN
BE POSSIBLE BY AFTERNOON...ESPECIALLY WITHIN THE AFOREMENTIONED AXIS
OF MOISTURE COINCIDING WITH THE BEST INSTABILITY /EAST OF THE BLUE
RIDGE/.

COLD FRONT STARTS TO PUSH EASTWARD THROUGH THE CWA IN THE
EVENING...LIKELY RESIDING EAST OF THE INTERSTATE 95 CORRIDOR BY
DAYBREAK WEDNESDAY. TREND WILL BE FOR LOWERING POPS FROM WEST TO
EAST THROUGH THE NIGHT AS POST-FRONTAL NORTHWEST WINDS BEGIN TO
BRING DRIER AIR INTO THE CWA.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
SYNOPTIC COLD FRONT WILL STILL BE WORKING ITS WAY THROUGH THE
EASTERN PORTION OF THE FORECAST AREA WEDNESDAY MORNING AND HAVE
MAINTAINED MORNING POPS FOR SOUTHERN TIP OF MARYLAND ALONG WITH
ADJACENT BAY AREAS AS LINGERING RAIN BANDS SLOWLY PUSH EAST
OFFSHORE. FORECAST SOUNDING SHOW MUCH DRIER/COOLER AIRMASS ADVECTING
INTO THE REGION BEHIND THE FRONT FOR THE REMAINDER OF
WEDNESDAY...AND WHILE AFTERNOON CU MAY DEVELOP WITH COLD POOL ALOFT
AND STRONG SURFACE MIXING/HEATING...AIRMASS LOOKS TOO DRY FOR
INSTABILITY SHOWERS AT THIS TIME. OTHERWISE TEMPS/HUMIDITY WILL
BE UNSEASONABLY COMFORTABLE FOR MID JULY WEDNESDAY AND THURSDAY.

BASE OF LARGE UPPER COLD CORE LOW SKIRTS NORTHERN/WESTERN MARYLAND
FOR THURSDAY AND WITH SOME SLIGHT INCREASE IN MOISTURE...MAY SEE
MORE CU AND ISOLATED SHOWERS POSSIBLE ACROSS THE REGION. HAVE KEPT
FORECAST DRY FOR NOW AS COVERAGE SHOULD BE VERY LOW. RETURN FLOW
SETS IN FOR FRIDAY WITH PWATS CLIMBING QUICKLY TO 1.50-1.75 INCHES
BY 00Z SAT. DECENT SHORT WAVE ACROSS THE OHIO VALLEY FRIDAY
AFTERNOON LOOKS TO PROVIDE A GOOD TRIGGER FRIDAY
AFTERNOON...MAINLY WEST OF I-95 TO BEGIN. MARGINAL DEEP LAYER
SHEAR AND CAPE LOOKS TO HINDER WIDESPREAD ORGANIZED CONVECTION
POTENTIAL HOWEVER. INCREASE IN MOISTURE WITH RETURN FLOW CONTINUES
INTO THE WEEKEND. SOUTHWEST FLOW ALOFT AND EMBEDDED SHORT WAVES
WILL BRING PEAKING HEATING STORM INITIATION EACH AFTERNOON.
INSTABILITY AND DEEP LAYER SHEAR BECOME MORE MODERATE AS
WELL...BRINGING A BETTER CHANCE FOR SOME ORGANIZED CONVECTION.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
SCATTERED TSTMS DEVELOPED ALONG AND EAST OF I-81 IN NRN VA...W/
THESE CELLS NOW THREATENING THE KIAD ZONE AND WILL EVENTUALLY THE
DC/BALT TAF SITES IN THE POST-20Z TIME RANGES. STILL HIT-OR-MISS
EFFECTS W/ LOCALIZED DOWNPOURS AND GUSTY WINDS.

THE TSTM ACTIVITY WILL SUBSIDE LATER THIS EVE...AFTER SUNSET W/
THE DECREASE IN HEATING. MINIMAL SHOWERS ACTIVITY OVERNIGHT.
THUNDERSTORMS ARE LIKELY AGAIN TUESDAY AFTERNOON/EVENING...THEN A
COLD FRONT MOVES THROUGH WITH A WIND SHIFT TO THE NORTHWEST /AND
DRYING/ TUESDAY NIGHT.

HIGH PRESSURE WILL BUILD INTO THE REGION FOR WEDNESDAY
INTO FRIDAY. A TROUGH OF LOW PRESSURE WILL BRING THE CHANCES OF
AFTERNOON/EVENING THUNDERSTORMS FRIDAY AND THROUGH THE WEEKEND.

&&

.MARINE...
STRONG GUSTY WINDS MAY ACCOMPANY THUNDERSTORMS THIS AFTERNOON/
EVENING AND AGAIN ON TUESDAY. BREEZY GRADIENT WINDS ALONG THE
LOWER PORTIONS OF THE MARYLAND BAY WARRANT A SCA FOR THE AFTN/EVE
HRS. COLD FRONT IS EXPECTED TO APPROACH THE CHESAPEAKE BAY LATE
TUESDAY NIGHT.

COOLER AND DRIER AIR OVERSPREADS WATERS WED. HWVR...GDNC SUGGESTS
THAT WNDS WONT EXCEED SCA CRITERIA. SINCE THERES A LTL UNCERTAINTY
AS TO WHETHER CDFNT MAY GET HUNG UP NEAR THE WATERS...WL KEEP GUSTS
CAPPED AT 15 KT.

SCA CONDITIONS MAY BE MET ON PORTIONS OF THE WATER WEDNESDAY
BEHIND A DEPARTING COLD FRONT. HIGH PRESSURE WILL BUILD INTO THE
REGION FOR THURSDAY INTO FRIDAY. A TROUGH OF LOW PRESSURE WILL
BRING THE CHANCES OF AFTERNOON/EVENING THUNDERSTORMS FRIDAY AND
THROUGH THE WEEKEND.

&&

.TIDES/COASTAL FLOODING...
WATER LEVELS SUBSIDED A BIT IN THE PAST FEW HRS BUT ARE AGAIN
CLOSING-IN ON AOB A HALF-FOOT ABV ASTRO PREDICTIONS. GOING INTO
THE LOWER H.T. CYCLE IN THE NEAR TERM BUT WILL NEED TO MONITOR THE
OVERNIGHT CYCLES FOR PERHAPS THE ONLY OTHER SITE TO WATCH IS SW
DC...BUT DO NOT HV THE CONFIDENCE TO ISSUE ADVYS ANYWHERE ATTM.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ534-
     537-543.

&&

UPDATE...GMS/AEB
PREV DISCUSSION...BPP/HTS

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
523 PM EDT MON JUL 14 2014

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0452 PM     MARINE TSTM WIND 1 S REAGAN NATIONAL AIR 38.85N  77.03W
07/14/2014  M43 MPH          ARLINGTON          VA   ASOS

            37-KNOT GUST MEASURED AT DCA.

&&

EVENT NUMBER LWX1400818

DH

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>