Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
561 FXUS01 KWBC 272025 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Sun Sep 27 2026 Valid 00Z Mon Sep 28 2026 - 00Z Wed Sep 30 2026 ...A round of heavy rain and embedded thunderstorms associated with the meandering Nor`easter is forecast to impact southern New England to the northern Mid-Atlantic through tonight and into Monday... ...Flash flood threat emerges and expands quickly across the Four Corners region as an upper trough interacts with tropical moisture from Polo and Odalys... The strong low-pressure system that has been impacting New England and the northern Mid-Atlantic over the weekend made landfall over central and southern New Jersey today as it gradually weakens. The center of this Nor`easter is moving southward in a cyclonic loop, brushing the southern coastline of New Jersey before gradually taking an east-northeast track and passing south of Long Island through Sunday night. As the final piece of an upper-level trough completely merges with the system, the Nor`easter will enter its gradual weakening stage. However, a batch of heavy rain with embedded thunderstorms forming on the eastside of the weakening system south of Long Island is expected to rotate toward and across southern New England and into much of New Jersey through tonight. The low-pressure center will not exit quickly, and southern New England will remain under the threat of moderate to heavy rain for much of Monday. Strong and gusty onshore wind will buffet coastal New England from Cape Cod northward, potentially reaching gale force Sunday night into early Monday. Light to moderate rain will then overspread the remaining areas of northern New England on Monday before the weakening Nor`easter finally exits into Nova Scotia by Tuesday evening. Outside of the Nor`easter, much less active weather is found across the rest of the country to end this weekend. However, this tranquil weather pattern will be short-lived as the threat of flash flooding emerges and then quickly expands across the Four Corners region over the next couple of days. This is in response to an upper-level trough moving onshore into California ingesting tropical moisture coming from the twin tropical cyclones Polo and Odalys currently over the eastern Pacific. Monday should see the initial expansion of showers and thunderstorms across much of the Four Corners states ahead of the upper trough. This will be followed by the core of the tropical moisture from Polo moving through northern Mexico on Tuesday, reaching New Mexico later that day. WPC is highlighting a large area of slight and moderate risk of flash flooding engulfing much of the Four Corners states Monday and Tuesday, with more focus toward New Mexico on Tuesday. Much of the region can expect to receive 2 inches of rainfall with much higher amounts likely due to localized terrain effects. There is uncertainty regarding the track of Polo`s remnants across northern Mexico and how much of Polo`s circulation remains by the time it reaches the U.S. Please stay tuned to this emerging flash flooding event across the Four Corners states over the next couple of days. Kong Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php $$