Prognostic Meteorological Discussion
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FXUS01 KWBC 201951
PMDSPD

SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
350 PM EDT THU JUL 20 2017

VALID 00Z FRI JUL 21 2017 - 00Z SUN JUL 23 2017

...A SLIGHT RISK OF SEVERE STORMS FOR THE LOWER GREAT LAKES/OHIO
VALLEY AND THE NORTHERN HIGH PLAINS THROUGH SUNDAY MORNING...

...HEAVY RAIN LIKELY OVER PARTS OF THE UPPER/MIDDLE MISSISSIPPI
VALLEY INTO THE WESTERN OHIO VALLEY ON FRIDAY...

...TEMPERATURES WILL AVERAGE 10 DEGREES ABOVE AVERAGE OVER PARTS
OF THE CENTRAL PLAINS/MIDDLE MISSISSIPPI VALLEY...

...ISOLATED HEAVY RAIN AND FLASH FLOODING POSSIBLE ACROSS THE
SOUTHWEST THROUGH THE WEEKEND...

CONDITIONS ARE SETTING UP FOR AN EXTENDED WET PERIOD FOR PORTIONS
OF THE UPPER MISSISSIPPI VALLEY AND GREAT LAKES. A
QUASI-STATIONARY FRONTAL BOUNDARY WILL BE PRESENT OVER THE NEXT
FEW DAYS SPANNING FROM THE NORTHERN MID-ATLANTIC/NORTHEAST TO THE
NORTHERN/CENTRAL PLAINS. MULTIPLE ROUNDS OF SHOWERS AND
THUNDERSTORMS WILL DEVELOP AND MOVE SLOWLY ALONG THIS BOUNDARY.
THE HIGHEST CONCENTRATION OF RAINFALL IS FORECAST ALONG A LINE
FROM SOUTHEAST MINNESOTA TO NORTHWEST INDIANA. THIS AREA HAS
ALREADY HAD RECENT PRECIPITATION, AND WITH AN ADDITIONAL 1 TO 3
INCHES ANTICIPATED, THE RISK FOR RAPID RUNOFF AND FLASH FLOODING
WILL INCREASE. A MODERATE RISK FOR EXCESSIVE RAINFALL HAS BEEN
ISSUED BY WPC. ADDITIONALLY, SPC HAS HIGHLIGHTED AN AREA HAVING A
SLIGHT FOR SEVERE THUNDERSTORMS TO DEVELOP FROM THE EASTERN
DAKOTAS TO WESTERN OHIO ON FRIDAY... AND EXPANDING NORTHWARD INTO
THE UPPER GREAT LAKES AND EASTWARD TO THE NORTHERN MID-ATLANTIC BY
SATURDAY. PLEASE REFER THE CONVECTIVE OUTLOOKS FROM SPC FOR MORE
INFORMATION ON THE SEVERE RISK.

MONSOONAL MOISTURE, DAYTIME HEATING AND UPPER-LEVEL ENERGY WILL
CONTINUE TO TRIGGER SHOWERS AND THUNDERSTORMS OVER PARTS OF THE
SOUTHWEST/GREAT BASIN EASTWARD TO THE CENTRAL/SOUTHERN ROCKIES
THROUGH THE WEEKEND. HIGHER RAINFALL RATES WILL REMAIN POSSIBLE
FOR MUCH OF THE SOUTHWEST AND SOUTHERN/CENTRAL ROCKIES, WHICH WILL
INCREASE THE RISK FOR FLASH FLOODING. SLIGHT RISKS FOR EXCESSIVE
RAINFALL WILL PERSIST OVER MUCH OF THIS REGION THROUGH SATURDAY
NIGHT.

MOISTURE RICH AIR OVER THE SOUTHERN MID-ATLANTIC/SOUTHEAST COAST
AND ACROSS THE GULF COAST STATES WILL INTERACT WITH DAYTIME
HEATING AND UPPER-LEVEL IMPULSES TO PRODUCE SHOWERS AND
THUNDERSTORMS. COVERAGE WILL INCREASE DURING THE LATE AFTERNOON
AND EVENING HOURS. ELSEWHERE, ONSHORE FLOW OFF THE PACIFIC WILL
AID IN PRODUCING RAIN OVER PARTS OF THE PACIFIC NORTHWEST THROUGH
LATE FRIDAY.


CAMPBELL


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





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