The Cumberland Times-News

CUMBERLAND, Md., April 29 — Mother Nature completely spoiled warm weather enthusiasts this month and also triggered fear with gardeners and those with agricultural interests thanks to the accompanying dry weather. Will Mother Nature try desperately to hold onto a sustainable cold pattern or will she relinquish her grip and let summer come with flying colors?

La Nina has finally ended and the Equatorial Pacific water temperatures are trending near average. While El Nino is a lock later this summer, it won’t develop in May. Historically, not having a full-fledged El Nino or La Nina in May but rather a neutral pattern translates to a warm month in western Maryland and the Potomac Highlands.

There are other competing signals in the short-term. A blocking pattern in the Arctic and high pressure ridge in Alaska will funnel colder temperatures into the region through May’s first week.

Another overwhelming signal for persistent cold temperatures in early May is a positive phase of the Pacific-North America Oscillation. The negative phase of this signal all winter long helped steer the storm track west of the Appalachians and brought more rain than snow. A positive phase favors a western ridge and eastern trough. For the first time since last winter, a western ridge will last for more than just a few days. It will help drive cold temperatures from Alaska into the Mid-Atlantic straight through the first week in May and bring snow showers to at least western Allegany and Garrett County.

We expect a chilly May start but mid-late month will bring exceptional warmth. It’ll be a month to remember with early month snow showers along and west of Route 36 followed by what we have mentioned in the 2023 publication of the Hagerstown Town and Country Almanack; record warmth on Mother’s Day.

Rainfall has fallen behind and drought has expanded from I-95 to almost I-81 as of late April. As we mentioned in the Prognosticator’s column on page 47, April has been very unkind to allergy suffers with dry, warm and windy weather. Unfortunately, analog or similar neutral ENSO (El Nino Southern Oscillation) years yield less rain than average in May.

Drought expansion into western Maryland and the Potomac Highlands will likely occur in May. The antecedent dry weather will be problematic for agricultural interests as we head into the fruit-filling phase of the growing season later in the month.

The late April and early May time frame will trigger a spring freeze. However, the final hard frost of the season will occur several days prior to the advertised big warmup for Mother’s Day. The general rule of thumb of waiting until after Mother’s Day to plant the spring garden applies to this year. If you want to get a head start earlier that week (May 7-12), you won’t get burned by a sudden hard frost later in May. In the last 20 years, the latest last spring freeze was May 21, 2002.

The unofficial start to summer, Memorial Day weekend, can be very warm or cloudy, foggy, damp and very chilly in western Maryland and the Potomac Highlands. This year we expect showers and thunderstorms at the beginning of the extended weekend and then dry weather with above-average temperatures.

National headlines in May will include expansion of drought into the Midwest while the Texas Gulf Coast will chip away at recent dry trends. While early month snow melt will continue to fill reservoirs in the West and California, periodic wet and snowy spells are expected from mid to late May.

The Midwest severe weather season will be a bit tamer than April but an uptick in severe thunderstorms is expected in southern Texas and along the Texas and Louisiana Gulf coast in May. It’s also possible a tropical depression could develop along a stalled front in the Deep South and bring localized heavy rain to the Gulf or southeast Atlantic coast early on Memorial Day weekend.

When we return in late May, we’ll dive into June and bring you the latest information on the summer outlook. Farmers are yearning for rain, so will Mother Nature pull through or will water budgets be inflated from a dry summer start?