724
FXUS21 KWNC 101811
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT APRIL 10 2025
SYNOPSIS: A QUICK, DEPARTING SHOT OF MUCH BELOW NORMAL TEMPERATURES BRINGING
FROST AND FREEZE CHANCES TO PORTIONS OF THE MID-ATLANTIC IS POSSIBLE AT THE
ONSET OF WEEK-2. FOLLOWING THE COLD CHANCES, AN AREA OF SURFACE LOW PRESSURE IS
FORECAST TO DEVELOP IN THE NORTHEAST AND SOUTHEASTERN CANADA BRINGING INCREASED
CHANCES FOR HIGH WINDS TO PARTS OF THE REGION. IN ALASKA, SURFACE LOW PRESSURE
BRINGS INCREASED CHANCES FOR HIGH WINDS TO SOUTHERN COASTAL REGIONS. FLOODING
REMAINS POSSIBLE INTO WEEK-2 ALONG PORTIONS OF THE MIDDLE AND LOWER MISSISSIPPI
RIVER.
HAZARDS
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE MID-ATLANTIC,
FRI, APR 18.
SLIGHT RISK OF HIGH WINDS FOR SOUTHERN COASTAL ALASKA, FRI, APR 18.
SLIGHT RISK OF HIGH WINDS FOR THE NORTHEAST, SAT-SUN, APR 19-20.
FLOODING POSSIBLE FOR THE MIDDLE AND LOWER MISSISSIPPI, AND LOWER OHIO RIVERS.
DETAILED SUMMARY
FOR SUNDAY APRIL 13 - THURSDAY APRIL 17:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY APRIL 18 - THURSDAY APRIL 24: A MID-LEVEL TROUGH IS FORECAST TO BE
OVER THE NORTHEASTERN CONTIGUOUS U.S. (CONUS) AT THE ONSET OF THE PERIOD WITH
AN ASSOCIATED SURFACE LOW PRESSURE SYSTEM OVER THE MARITIME PROVINCES OF
CANADA. THESE FEATURES ARE LIKELY TO BRING A QUICK SHOT OF MUCH BELOW NORMAL
TEMPERATURES INTO PORTIONS OF THE MID-ATLANTIC AT THE ONSET OF WEEK-2.
TEMPERATURES ARE FORECAST BY DETERMINISTIC MODEL RUNS AND THE PROBABILISTIC
EXTREMES TOOLS (PETS) TO FALL BELOW 40 DEG F. ACROSS PORTIONS OF THE COASTAL
PLAIN AND PIEDMONT OF THE MID-ATLANTIC ON DAY 8 INCREASING CHANCES FOR FROST
AND FREEZES. THEREFORE, AN ASSOCIATED MUCH BELOW NORMAL TEMPERATURES HAZARD IS
FORECAST FOR FRI, APR 18.
FOLLOWING THIS INITIAL WAVE OF LOW PRESSURE A SECOND, WEAKER MID-LEVEL AND
ASSOCIATED SURFACE LOW, IS FORECAST TO DEVELOP. THIS SYSTEM IS LIKELY TO PULL
WARMER AIR NORTHWARD ENDING THE RISK FOR FROST AND FREEZING TEMPERATURES BUT
INCREASES THE RISK OF HIGH WINDS TO PORTIONS OF THE NORTHEAST. THIS IS
SUPPORTED BY THE PETS AND RAW ENSEMBLE GUIDANCE. THEREFORE, A SLIGHT RISK OF
HIGH WINDS IS POSTED FOR APR 19-20, AS THIS SYSTEM MOVES THROUGH AND THEN AWAY
FROM THE NORTHEAST.
IN THE PLAINS AND FOUR CORNERS, THERE ARE SOME INDICATIONS THAT HIGH WINDS MAY
IMPACT PARTS OF THE REGION THROUGHOUT MUCH OF THE WEEK-2 PERIOD. THESE SIGNALS
ARE RELATIVELY WEAK AT THIS TIME AND THEREFORE, NO ASSOCIATED HAZARD IS POSTED
TODAY. HOWEVER, THE LACK OF STRONG WINDS WOULD NOT PRECLUDE THE CHANCE FOR FIRE
WEATHER ACROSS THE REGION AS TEMPERATURES ARE FORECAST TO BE ABOVE-NORMAL
ACROSS THE REGION AND RELATIVE HUMIDITY REMAINS FORECAST TO BE LOW BY THE
ECENS. THEREFORE, EVEN MODERATE WINDS COULD INCREASE RISKS ACROSS THIS REGION.
IN THE CENTRAL CONUS, GIVEN THE COPIOUS ANTECEDENT RAINFALL AND RECURRING
FLOODING CONCERNS IN THIS REGION, A FLOODING POSSIBLE HAZARD REMAINS POSTED FOR
PORTIONS OF THE LOWER OHIO, MIDDLE AND LOWER MISSISSIPPI VALLEYS DUE TO THE
POTENTIAL FOR NEW AND RENEWED RISES IN RIVER LEVELS. WHILE MAIN CHANNELS ARE
ALREADY VERY HIGH, AND THUS LIKELY WON’T RESPOND TOO MUCH TO ADDITIONAL
PRECIPITATION, TRIBUTARIES AND STREAMS WILL BE MORE SUSCEPTIBLE TO RENEWED
FLOODING OR FLASH FLOODING IF ADDITIONAL RAINFALL OCCURS.
IN ALASKA, MULTIPLE MODELS DEPICT A SURFACE LOW PRESSURE SYSTEM TRACKING ACROSS
THE GULF OF ALASKA AT THE END OF WEEK-1 INTO EARLY WEEK-2. THIS SYSTEM IS
DEPICTED WITH STRONG PRESSURE GRADIENTS AND DEVELOPING STRONG WINDS THAT MAY
POTENTIALLY AFFECT COASTAL AREAS OF SOUTHEAST ALASKA. THE ECMWF AND GEFS PETS
FOR MAXIMUM WIND SPEED INDICATE AT LEAST A 20% CHANCE OF 3-DAY WIND SPEEDS
EXCEEDING THE 85TH PERCENTILE AND AT LEAST 40MPH, SO A SLIGHT RISK OF HIGH
WINDS IS POSTED FOR COASTAL ALASKA FROM PRINCE WILLIAM SOUND EASTWARD THROUGH
SOUTHEAST ALASKA FOR APR 18. IN ADDITION, AS SPRING CONTINUES AND DAILY
INCOMING SOLAR RADIATION FLUX TOTALS INCREASE, ICE-BOUND RIVERS WILL BEGIN TO
BREAK UP. THERE IS NO ASSOCIATED HAZARD POSTED AT THIS TIME BUT THIS SITUATION
WILL BE CLOSELY MONITORED IN THE COMING DAYS AND WEEKS AS CONDITIONS CAN
QUICKLY CHANGE, LEADING TO THE POTENTIAL FOR ICE JAMS AND ASSOCIATED FLOODING.
FORECASTER: RYAN BOLT
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