ITHACA, N.Y. — Welcome to March, ladies and gentlemen, Ithaca’s most temperamental month of the year. Climatologically, it’s the month with the widest statistical variation from “normal” temperatures, meaning March is often well-below or well-above normal temperature-wise, and tends to have larger tails than the standard “Bell curve” distribution of temperatures.

Sometimes, like this particular March, we get both well-below normal and well-above normal temperatures within a few days of each other. Life’s more exciting when you rotate between parkas and t-shirts in the same week.

There’s nothing too disruptive in this week’s forecast, with some snow showers related to lake-enhanced snowbands today and tonight, and rain with a warm front Tuesday. Other than that, gradually warming conditions will bring temperatures well into the 60s with sunny skies by Thursday, though some rain looks possible over the weekend.

Your Weekly Weather

To be a little more scientific for March’s wide temperature swings, it boils down to the jet stream. The mid-latitude jet stream, that fast, narrow band of flowing air in the upper atmosphere, is maintained by temperature and pressure gradients between warmer mid-latitude and colder polar regions. This time of the year, as the sun’s angle starts to change considerably around spring equinox, the polar latitudes start to warm up, faster than the subtropics do, and the gradients weaken.

This causes the jet stream to meander and lets mid-latitude storm systems shape more of its path, with the warm and cold surges of air that go with respective ridges and troughs. There’s still plenty of cold air in the polar regions for a bitter cold snap, and developing expanses of milder air with greater Northern Hemisphere solar radiation can surge into the region as well. This late-winter jet stream meandering may be exacerbated by climate change as polar warm faster than lower latitudes overall, and is an area of active research.

Anyway, today’s weather isn’t too exciting, with a weak “Alberta Clipper” low rapidly moving eastward across the region. With the lack of moisture, weak core and rapid motion, impacts are largely limited to mostly cloudy to overcast skies and a quick coating of snow at most, with highs in the low 30s. The clipper moves out of the Finger Lakes a little after sunset, with the showers tapering off from west to east and skies partially clearing overnight. High pressure over the Southeastern United States will build in, and with the eastward shift of that high towards the Atlantic Coast, that will usher a a light southerly wind that will keep temperatures fairly stable, in the mid 20s for lows.

Monday will be a milder and tranquil day as that high shifts into the Atlantic Ocean and grows a little stronger, resulting in enhanced southerly flow. This will be enhanced a little more by a developing low pressure system over the Southern Plains, which unlike most storms is expected to pass around the high to the south, over the Gulf Coast and leaving the Northeast alone. Skies will be partly to mostly cloudy Monday with a high around 50°F. Monday night will be dry and mostly cloudy with a low in the mid 30s.

There is a shortwave (pulse of instability) likely to pass through on the periphery of the high pressure system Tuesday, and this likely closes off into a weak low pressure system as it moves across a stationary trough, over the Great Lakes into New England. The further south one is, the less of an issue this short wave will be – for Ithaca, generally expect a mostly cloudy day with some light rain showers (totals will be less than one-tenth of an inch), primarily in the afternoon and evening, with highs around 50°F. The rain showers should end by midnight, with mostly cloudy skies and lows in the lower 30s Tuesday night.

Wednesday will be a pleasant day for March, as southerly flow on the backside of the high pressure system and enhanced by the low over the Georgia coast result in mild and sunny conditions over Tompkins County. Plan for a few passing clouds and highs in the mid 50s. Wednesday night will be dry and partly cloudy with lows in the upper 30s.

Thursday will see a continuation of that southerly flow with the low pressure system passing well to the southwest of the region. It will be mostly sunny with highs in the mid 60s. Thursday night will see partly cloudy skies and lows around 40°F. It should be noted that as this will be a dry period with gradually warming conditions and with much of the thicker long-duration ice having already melted off, there isn’t much of a flooding risk expected from meltwater during this period.

Friday will remain dry, though the next storm system will begin to move towards the Finger Lakes, a low that develops in the Southern Great Plains and lifts northeastward through the Western Great Lakes. This means that Upstate will remain in the warm sector even as it approaches. Skies will be mostly cloudy Friday with highs in the low to mid 60s. The rain will begin to move in after sunset Friday, with the bulk of it arriving midnight – it’s a little too early to give amounts, but it looks to be scattered showers rather than a steady rain. Lows Friday will be in the low 40s.

Next weekend will start on the wet side with overcast conditions and periods of rain Saturday and highs in the low 50s. The low should lift far enough northward that by the time it crosses Ithaca’s longitude that there will be little in the way of snow, and lows Saturday night will be in the upper 30s with rain tapering off in the Sunday morning hours. Sunday is looking dry and partly cloudy with highs in the upper 40s.

Graphics courtesy of the NOAA Climate Prediction Center.

Extended Outlook

Looking into the first week of astronomical spring, the large-scale medium-range models favor a jet stream ridge over the East Coast and West Coast. However, that means different things precipitation-wise. In the west, that means warmer, drier air funneled in from the Mexican border deserts and Western Sierra Madres. In the east, warmer air will be channeled in from the Lower Mississippi River Valley and Gulf of Mexico, decidedly more moist places that will result in elevated chances for above-normal precipitation in the last third of the month. We might see an early start to April mildness and April showers.

Brian Crandall

Brian Crandall reports on housing and development for the Ithaca Voice. He can be reached at bcrandall@ithacavoice.com.