651
FXUS01 KWBC 030800
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
359 AM EDT SAT MAY 03 2025
VALID 12Z SAT MAY 03 2025 - 12Z MON MAY 05 2025
...UPPER-LEVEL OMEGA BLOCK TO FORM ACROSS THE CONUS, LEADING TO
PERIODS OF UNSETTLED WEATHER AND LARGE TEMPERATURES CONTRASTS THIS
WEEKEND...
...WIDESPREAD SHOWERS AND THUNDERSTORMS EXPECTED AHEAD OF A COLD
FRONT FROM THE OHIO VALLEY TO THE EAST COAST SATURDAY WITH SOME
SEVERE WEATHER AND ISOLATED FLASH FLOODING POSSIBLE...
THE MID- TO UPPER LEVEL FLOW WILL BECOME INCREASINGLY AMPLIFIED
THIS WEEKEND IN AN OMEGA BLOCK PATTERN AS UPPER LOWS DEVELOP OVER
THE OHIO VALLEY AND WEST COAST. IN THE EAST, THE FIRST OF THE
UPPER-LOWS WILL DEVELOP SATURDAY AS AN UPPER-LEVEL TROUGH PASSES
OVER THE OHIO VALLEY. AN ACCOMPANYING SURFACE LOW PRESSURE
SYSTEM/COLD FRONT STRETCHING FROM NEW ENGLAND SOUTHWEST THROUGH
THE OHIO VALLEY AND INTO THE LOWER MISSISSIPPI VALLEY/GULF COAST
WILL PROVIDE THE FOCUS FOR WIDESPREAD SHOWERS AND THUNDERSTORMS
ACROSS THE REGION THIS MORNING AND EASTWARD INTO THE MID-ATLANTIC
AND SOUTHEAST SATURDAY AFTERNOON/EVENING. SUFFICIENT INSTABILITY
ALONG WITH INCREASING WINDS AS THE UPPER-LOW CHURNS OVERHEAD MAY
LEAD TO A FEW CLUSTERS OF MORE INTENSE THUNDERSTORMS CAPABLE OF
SEVERE WEATHER. THE STORM PREDICTION CENTER HAS HIGHLIGHTED
PORTIONS OF SOUTHERN NEW ENGLAND AND THE MID-ATLANTIC SOUTHWARD
THROUGH THE CAROLINAS, GENERALLY ALONG AND EAST OF THE
APPALACHIANS, IN A SLIGHT RISK (LEVEL 2/5). LARGE HAIL AND
DAMAGING WINDS WILL BE THE MAIN THREATS, THOUGH AN ISOLATED
TORNADO OR TWO WILL BE POSSIBLE. IN ADDITION, A MOIST AIRMASS IN
PLACE AHEAD OF THE FRONT WILL SUPPORT MODERATE TO LOCALLY HEAVY
RAINFALL WITH ISOLATED FLASH FLOODING POSSIBLE. THE FRONT WILL
PROGRESS SLOWLY EASTWARD OVERNIGHT SATURDAY AND INTO THE DAY
SUNDAY, WITH CLEARING CONDITIONS TO THE WEST OVER THE LOWER
MISSISSIPPI/TENNESSEE VALLEYS BUT CONTINUED SHOWER AND
THUNDERSTORM CHANCES ALONG THE EAST COAST AND WESTWARD THROUGH THE
OHIO VALLEY UNDER THE UPPER-LOW. MODERATE TO LOCALLY HEAVY RAIN
AND ISOLATED FLASH FLOODING WILL REMAIN POSSIBLE, PARTICULARLY
FROM THE LOWER GREAT LAKES EASTWARD THROUGH THE MID-ATLANTIC.
TO THE WEST, SOME SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED
THIS WEEKEND IN THE PRESENCE OF MOIST, UPSLOPE FLOW ALONG THE
SOUTHERN ROCKIES AS A FRONTAL BOUNDARY LINGERS IN THE REGION. SOME
ISOLATED FLASH FLOODING WILL BE POSSIBLE ACROSS PORTIONS OF
EASTERN NEW MEXICO, PARTICULARLY FOR TERRAIN SENSITIVE REGIONS AND
AREA BURN SCARS. MORE WIDESPREAD PRECIPITATION CHANCES WILL BEGIN
TO EXPAND SOUTHWARD THROUGHOUT THE WEST AS AN UPPER-LEVEL TROUGH
DIVES SOUTHWARD ALONG THE WEST COAST, WITH A SECOND UPPER-LEVEL
LOW FORMING AND SOLIDIFYING THE BLOCKY PATTERN ACROSS THE CONUS.
SHOWERS AND SOME THUNDERSTORMS IN THE PACIFIC NORTHWEST THIS
MORNING WILL SPREAD INTO PORTIONS OF THE NORTHERN ROCKIES, GREAT
BASIN, AND CALIFORNIA THROUGH SATURDAY AFTERNOON AND EVENING.
STORMS WILL CONTINUE SUNDAY THROUGHOUT THE NORTHERN ROCKIES AND
GREAT BASIN, AS WELL AS THE AFOREMENTIONED SOUTHERN ROCKIES/FOUR
CORNERS REGION, AS THE UPPER-LEVEL LOW REMAINS IN PLACE.
ACCUMULATING SNOW IS EXPECTED FOR SOME OF THE HIGHER ELEVATIONS OF
REGIONAL MOUNTAIN RANGES, MOST NOTABLY THE SIERRA NEVADA ON
SATURDAY AND THEN PORTIONS OF THE NORTHERN ROCKIES IN MONTANA AND
THE SAN JUANS IN COLORADO ON SUNDAY. DRY ANTECEDENT CONDITIONS,
GUSTY WINDS, AND COMPARATIVELY LOW RELATIVE HUMIDITY OVER
SOUTHWESTERN NEW MEXICO, SOUTH OF THE UNSETTLED WEATHER COVERING
MOST OF THE WEST, HAS PROMPTED A CRITICAL RISK OF FIRE WEATHER
CONDITIONS (LEVEL 2/3) FROM THE STORM PREDICTION CENTER FOR
SUNDAY.
THE AMPLIFYING, BLOCKY PATTERN WILL ALSO LEAD TO INCREASING
TEMPERATURE CONTRASTS FROM COAST-TO-COAST AS SOME AREAS OF THE
COUNTRY WILL SEE WELL BELOW AVERAGE CONDITIONS WHILE OTHERS WILL
SEE WELL ABOVE AVERAGE CONDITIONS. FORECAST HIGHS UNDER THE
EASTERN UPPER-LOW WILL BE WELL BELOW AVERAGE, PARTICULARLY ACROSS
PORTIONS OF THE MIDWEST/OHIO VALLEY, AS TEMPERATURES ONLY REACH
INTO THE 50S AND 60S. HIGHS FURTHER SOUTH INTO THE TENNESSEE/LOWER
MISSISSIPPI VALLEYS AND SOUTHERN PLAINS WILL BE A BIT WARMER BUT
STILL BELOW AVERAGE, ONLY REACHING INTO THE 70S FOR MOST
LOCATIONS. HIGHS ALONG THE IMMEDIATE EAST COAST WILL REMAIN WELL
ABOVE AVERAGE ON SATURDAY AS TEMPERATURES RISE INTO THE 60S AND
70S IN NEW ENGLAND AND THE 80S FROM THE MID-ATLANTIC SOUTH. THE
APPROACHING COLD FRONT AND PRECIPITATION SUNDAY WILL BRING
TEMPERATURES ABOUT 10 DEGREES COOLER AND MUCH CLOSER TO AVERAGE ON
SUNDAY. FORECAST HIGHS UNDER THE WESTERN UPPER-LOW WILL ALSO BE
WELL BELOW AVERAGE, WITH 50S AND 60S EXPECTED FROM THE PACIFIC
NORTHWEST SOUTH THROUGH CALIFORNIA SATURDAY. THESE COOLER
TEMPERATURES WILL SPREAD INTO THE GREAT BASIN SUNDAY, WITH HIGHS
IN THE 50S AND 60S, AND INTO THE SOUTHWEST, WITH HIGHS ONLY INTO
THE 70S. IN CONTRAST, TEMPERATURES UNDER A BUILDING UPPER-LEVEL
RIDGE BETWEEN THE LOWS WILL BE WELL ABOVE AVERAGE AS HIGHS SOAR
INTO THE 70S AND 80S ACROSS MUCH OF THE NORTHERN/CENTRAL ROCKIES
AND INTO THE NORTHERN PLAINS/UPPER GREAT LAKES. SOME LOCATIONS
ALONG THE NORTHERN HIGH PLAINS MAY REACH THE UPPER 80S ON SUNDAY,
UPWARDS OF 25-30 DEGREES ABOVE AVERAGE.
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