The severe weather threat shifts into the Mississippi Valley, while snowdevelops over the Northwest on Tuesday. Scattered showers andthunderstorms are expected to propagate into the Upper/Middle MississippiValley Tuesday morning and then over the Lower Mississippi Valley Tuesdayafternoon. SPC has another Enhanced Risk of Severe Thunderstorms out overparts of southeast Iowa, northern Missouri and west-central Illinois witha broader Slight Risk (level 2/5) area extending from northern Iowa downto the ArkLaTex on Tuesday. Scattered severe storms capable of producingsignificant/severe hail and tornadoes is forecast where the Enhanced Riskis currently in effect. Excessive Rainfall threats remain marginal overthe same areas with the possibility of a targeted Slight Risk area beingissued as we get closer to the event.Snow will likely develop on the backside of a pair of cold fronts pushingthrough the Northwest on Tuesday/Tuesday night, while thunderstorms movefarther into the Upper Mississippi Valley and Midwest. Snow accumulationsof around 6-12 inches are likely over the ranges of northwestern Wyominginto southern Montana, while 8-18 inches with isolated higher amountspossible over the Bighorn Mountains. Showers and thunderstorms move intothe Mid-Atlantic and Northeast on Wednesday with a Slight Risk of SevereStorms over parts of the Lower Ohio Valley into the Mid-South according tothe SPC. Mid to upper-level troughing over the northern tier will supportgenerally average to below average temperatures across that area over thenext couple of days while ridging over the southern tier will supportabove average temps.