Prognostic Meteorological Discussion
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FXUS01 KWBC 210732
PMDSPD

SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
332 AM EDT FRI JUL 21 2017

VALID 12Z FRI JUL 21 2017 - 12Z SUN JUL 23 2017

...HOT AND HUMID CONDITIONS ARE EXPECTED TO PERSIST FROM THE
CENTRAL PLAINS AND MIDDLE MISSISSIPPI VALLEY TO THE MID-ATLANTIC
STATES FRIDAY AND SATURDAY...

...HEAVY RAIN AND SEVERE STORMS WILL BE POSSIBLE ALONG A WAVY
FRONTAL BOUNDARY STRETCHED FROM THE UPPER MIDWEST AND GREAT LAKES
TO THE OHIO VALLEY AND NORTHERN MID-ATLANTIC REGION...

...MONSOONAL MOISTURE WILL KEEP LOCALIZED FLASH FLOODING A THREAT
FROM THE SOUTHWEST INTO THE SOUTHERN AND CENTRAL ROCKIES OVER THE
NEXT FEW DAYS...

HOT AND HUMID CONDITIONS WILL PERSIST BENEATH UPPER RIDGING
EXPANDING FROM THE CENTRAL PLAINS AND MIDDLE MISSISSIPPI VALLEY TO
THE MID-ATLANTIC STATES FRIDAY AND SATURDAY.  WIDESPREAD EXCESSIVE
HEAT WARNINGS AND HEAT ADVISORIES REMAIN IN EFFECT WHERE DAYTIME
TEMPERATURES IN THE MID TO UPPER 90S WILL COMBINE WITH HIGH DEW
POINTS TO CREATE TRIPLE DIGIT HEAT INDICES.  LOCATIONS ACROSS THE
CENTRAL PLAINS AND MIDDLE MISSISSIPPI VALLEY SHOULD SEE SOME
RELIEF FROM THE HEAT SATURDAY NIGHT INTO SUNDAY AS THE RIDGE
SUPPRESSES ALOFT AND A COLD FRONT SINKS SOUTHWARD THROUGH THE
REGION.

NORTH OF THE EXCESSIVE HEAT, RAIN AND THUNDERSTORMS WILL FOCUS
ALONG A WAVY FRONTAL BOUNDARY EXPECTED TO STRETCH FROM THE UPPER
MIDWEST AND GREAT LAKES TO THE OHIO VALLEY AND NORTHERN
MID-ATLANTIC REGION FRIDAY AND INTO THE WEEKEND.  GIVEN THE AMOUNT
OF AVAILABLE MOISTURE AND INSTABILITY, DEVELOPING CONVECTION WILL
HAVE THE POTENTIAL TO BECOME ORGANIZED AND PRODUCE FLASH FLOODING
AND SEVERE WEATHER.  PLEASE REFER TO WPC`S EXCESSIVE RAINFALL
FORECASTS AND SPC`S CONVECTIVE OUTLOOKS FOR THE LATEST INFORMATION
ON THE THREAT FOR FLASH FLOODING AND SEVERE WEATHER.

THE COMBINATION OF MONSOONAL MOISTURE AND WEAK IMPULSES OF ENERGY
ALOFT WILL HELP FOSTER ADDITIONAL DAYS OF AFTERNOON/EVENING
CONVECTION AND LOCALIZED FLASH FLOODING ACROSS PORTIONS OF THE
SOUTHWEST AND SOUTHERN/CENTRAL ROCKIES FRIDAY AND SATURDAY.

ELSEWHERE, DAYTIME HEATING WILL HELP TRIGGER AFTERNOON SHOWERS AND
THUNDERSTORMS WITHIN A MOIST AIRMASS IN PLACE ACROSS THE SOUTHEAST
AND GULF COAST STATES, WHILE A FRONTAL SYSTEM APPROACHING BRITISH
COLUMBIA COULD BRING MOSTLY LIGHT PRECIPITATION INTO THE EXTREME
NORTHWESTERN CORNER OF THE NATION.


GERHARDT


GRAPHICS AVAILABLE AT
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP
$$




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