Details from the National Weather Service
* WHAT...Temperatures as low as 35 will result in frost formation. * WHERE...Portions of northern Indiana and northwest Ohio. * WHEN...From 1 AM EDT /midnight CDT/ to 9 AM EDT /8 AM CDT/ Monday. * IMPACTS...Frost could harm sensitive outdoor vegetation. Sensitive outdoor plants may be killed if left uncovered. Take steps now to protect tender plants from the cold.
Weather Watch run of Sun Oct 18, 6:45 PM
What is happening now and what to watch for: official watches and warnings, the risks in the days ahead, and where Somerset stands with the next front.
Weather risks
The frost chance is the chance the station's low (5 feet up) reaches 36° or colder: on clear, calm nights the grass is then at 32° or below and ice forms on it and on rooftops. A freeze means the 5-foot air reaching 32° or colder. Frost and freeze chances come from our forecast low and its uncertainty, and tested reliable on the past year: nights given about a 70% chance happened about 70% of the time. Official watches and warnings appear in a banner at the top of the page as soon as the National Weather Service issues them.
Frontal watch
No frontal signature in any model for the next 7 days.
- Cold front: 580 miles to the northwest · Somerset is ahead of it
- Warm front: 866 miles to the northeast · Somerset is behind it
- Trough: 294 miles to the south-southwest
- Leading edge · pressure falling, south-southwest wind, humid air, with a front on the map or in the models
- In the front · wind veering toward west-northwest, dew point dropping, pressure turning up
- Trailing edge · steady northwest wind, pressure rising, air clearly drier
No frontal phase right now.
The pressure has fallen 1.9 mb over the last 6 hours, more than its normal daily swing. The wind is from the south, and the air is much drier than normal for this hour (dew point 13° below normal). Falling pressure with humid air flowing in from the south is what this station sees ahead of an approaching storm system or cold front.
A frontal passage here looks like this: the dew point drops below normal, the pressure climbs back after bottoming out, the wind veers from southwest to northwest, and in daylight the sky often clears. Shading shows the phase called each hour from the station's own readings. Left of the dotted "now" line is what the station measured; to the right, the green dashed lines mark when the models expect a front. Sky clearness is the solar sensor's reading divided by what a cloudless sky would give at that hour (1 = clear), shown only when the sun is high enough to judge.
| When | Dew point | Temperature | Pressure | Wind | On national map |
|---|---|---|---|---|---|
| Sat Oct 17, 1 AM | −10° | −1° | +9.8 mb | NW → N | - |
| Wed Oct 7, 9 PM | −10° | −13° | +4.2 mb | W → WNW | yes |
| Sun Oct 4, 7 PM | −7° | −10° | +2.2 mb | W → NNW | yes |
| Fri Oct 2, 8 AM | −13° | −18° | +8.0 mb | N → NNE | yes |
| Sun Sep 13, 7 PM | −9° | −7° | +6.1 mb | NNW → N | no |
| Sun Aug 23, 7 PM | −6° | −7° | +1.2 mb | W → NNW | no |
Detected from the station's own readings: dew point at least 5° lower than normal, wind veered toward the northwest, pressure up. About a third of the passages felt here are drawn as fronts on the national map; the rest are real but weaker or unanalyzed boundaries.
What the barometer alone says Experimental
Reading the station…
The Zambretti forecaster, a rule of thumb from 1915 built into many home barometers: it reads only the sea-level pressure, whether it has risen or fallen over the last 3 hours, and the wind direction, and looks the combination up in a table of 26 outlooks from "settled fine" to "stormy, much rain". It knows nothing else, so treat it as a second opinion from one instrument, not a forecast.