604
FXUS01 KWBC 180759
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
358 AM EDT MON SEP 18 2023
VALID 12Z MON SEP 18 2023 - 12Z WED SEP 20 2023
...HEAVY RAINFALL WITH LOCALIZED FLASH FLOODING POSSIBLE FOR NEW
ENGLAND MONDAY...
...HEAVY RAIN AND SEVERE STORM CHANCES RETURN TO PARTS OF THE
SOUTHERN PLAINS ON TUESDAY...
...HOT LATE SUMMER TEMPERATURES FOR THE HEARTLAND TO START THE
WEEK...
SHOWER AND STORM CHANCES SHOULD DIMINISH FOR MUCH OF THE EAST
COAST THIS MORNING AS A PAIR OF FRONTAL SYSTEMS PUSH OFF INTO THE
ATLANTIC. HOWEVER, AN ORGANIZING LOW PRESSURE SYSTEM JUST OFF THE
COAST WILL TRACK NORTHWARD TOWARDS NEW ENGLAND, HELPING TO FUNNEL
WARM, VERY MOIST AIR INTO THE REGION. WIDESPREAD MODERATE TO
LOCALLY HEAVY RAINFALL IS FORECAST TO PUSH NORTHWARD THROUGH MUCH
OF NEW ENGLAND THROUGH THE DAY MONDAY, WITH THE MOST CONSISTENT,
HEAVIEST RAINFALL EXPECTED CLOSER TO THE ATLANTIC COAST. A SLIGHT
RISK OF EXCESSIVE RAINFALL (LEVEL 2/4) HAS BEEN INTRODUCED FOR
PORTIONS OF COASTAL AND DOWNEAST MAINE WHERE WETTER ANTECEDENT
CONDITIONS, INCLUDING RAINFALL ASSOCIATED WITH LEE THIS PAST
WEEKEND, WILL LEAD TO A LOCALLY HIGHER CHANCE FOR SOME SCATTERED
INSTANCES OF FLASH FLOODING. RAIN CHANCES SHOULD CLEAR FROM SOUTH
TO NORTH THROUGH EARLY TUESDAY MORNING. ADDITIONALLY, WET WEATHER
IS EXPECTED ACROSS MUCH OF THE CENTRAL AND SOUTHERN FLORIDA
PENINSULA AS THE SLOW-MOVING COLD FRONT LINGERS OVER THE REGION,
SPARKING WIDESPREAD DAILY THUNDERSTORM CHANCES EARLY THIS WEEK.
FORECAST HIGHS ARE GENERALLY BELOW AVERAGE BROADLY ACROSS THE EAST
FOLLOWING THE FRONTAL PASSAGES, WITH 60S AND 70S FROM THE MIDWEST
TO THE NORTHEAST, UPPER 70S TO MID-80S FOR THE SOUTHEAST, AND
UPPER 80S TO LOW 90S FOR FLORIDA.
A SUBTLE UPPER-LEVEL WAVE IS FORECAST TO EJECT EASTWARD FROM THE
ROCKIES OVER THE SOUTHERN PLAINS TUESDAY, PASSING OVER VERY MOIST
SOUTHERLY RETURN FLOW FROM THE GULF OF MEXICO AND INTERACTING WITH
A LINGERING FRONTAL BOUNDARY, LEADING TO INCREASED SHOWER AND
THUNDERSTORM CHANCES BY TUESDAY AFTERNOON. THE STORM PREDICTION
CENTER HAS ISSUED A SLIGHT RISK (LEVEL 2/5) OF SEVERE
THUNDERSTORMS FROM NORTHWEST TEXAS INTO OKLAHOMA AS SOME OF THE
MORE ROBUST INITIAL STORMS MAY PRODUCE SOME LARGE HAIL AND
DAMAGING WIND GUSTS. IN ADDITION, THE POTENTIAL FOR VERY HEAVY
DOWNPOURS AS WELL AS FOR STORMS TO CONGEAL INTO MORE WIDESPREAD
CLUSTERS INTO THE EVENING HOURS MAY LEAD TO SOME FLASH FLOOD RISK,
AND A SLIGHT RISK OF EXCESSIVE RAINFALL HAS BEEN INTRODUCED.
AN UPPER-LEVEL RIDGE SHIFTING EASTWARD OVER THE PLAINS WILL
CONTINUE TO LEAD TO UNSEASONABLY HOT LATE SUMMER HIGH TEMPERATURES
FOR MUCH OF THE HEARTLAND TO START THE WEEK. FORECAST HIGHS ARE IN
THE 80S TO LOW 90S BROADLY ACROSS THE CENTRAL AND NORTHERN PLAINS
WITH LOW TO MID-90S EXPECTED FOR THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY. THESE HIGHS WILL BE RUNNING 10-20 DEGREES
ABOVE AVERAGE, PARTICULARLY OVER THE NORTHERN PLAINS. AN
UPPER-LEVEL WAVE/COLD FRONT PUSHING EASTWARD FROM THE PACIFIC
NORTHWEST WILL BEGIN TO BRING SOME COOLER, MORE SEASONABLE
TEMPERATURES TO NORTHERN PORTIONS OF THE HIGH PLAINS ON TUESDAY,
WITH 70S FORECAST. CONDITIONS WILL BE MOSTLY DRY BROADLY ACROSS
THE WESTERN AND CENTRAL U.S. OUTSIDE OF THE AFOREMENTIONED STORM
CHANCES OVER THE SOUTHERN PLAINS. THE COMBINATION OF HOT
TEMPERATURES, LOW HUMIDITY, AND GUSTY WINDS HAVE PROMOTED A
CRITICAL RISK OF FIRE WEATHER (LEVEL 2/3) FROM THE STORM
PREDICTION CENTER FOR PORTIONS OF THE NORTHERN HIGH PLAINS MONDAY.
HIGHS IN THE 60S AND 70S WILL BE A BIT BELOW AVERAGE FOR THE
PACIFIC NORTHWEST AND COASTAL CALIFORNIA. SEASONABLE HIGHS IN THE
80S ARE FORECAST FOR CENTRAL CALIFORNIA INTO THE GREAT BASIN WITH
90S EXPECTED FOR THE DESERT SOUTHWEST.
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