Thaw (weather)

Thaw (weather)

Thaw is the period when the snow and ice melt, at the end of the winter, in cold climates.

A special thaw, outside normal season, is January thaw.

January thaw

The January thaw is an observed but unexplained temperature rise in mid-winter found in mid-latitude North America.

Sinusoidal estimates of expected temperatures, for northern locales, usually place the lowest temperatures around January 23 and the highest around July 24, and provide fairly accurate estimates of temperature expectations. Actual average temperatures in North America usually significantly differ twice over the course of the year:

* Mid-autumn temperatures tend to be warmer than predicted by the sinusoidal model, creating the impression of extended summer warmth known as Indian summer.
* For five days around January 25, temperatures are usually significantly warmer than predicted by the sinusoidal estimate, and also warmer than neighboring temperatures on both sides.

During this "thaw" period, usually lasting for about a week, temperatures are generally about 10 °F (6 °C) above normal. This varies from year to year, and temperatures fluctuate enough that such a rise in late-January temperature would be unremarkable; what is remarkable (and unexplained) is the tendency for such rises to occur more commonly in late-January than in mid-January or early February, which sinusoidal estimates have to be slightly warmer.

In some regions (such as northern Canada) this phenomenon will not be manifest as a "thaw" in the technical sense, since temperatures will remain below freezing.

The January thaw is believed to be a weather singularity.

External links

* [http://www.islandnet.com/~see/weather/almanac/arc2002/alm02jan2.htm "January Thaw: Winter Cold Relief"]


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  • thaw´er — thaw «th», verb, noun. –v.t. 1. to melt (ice, snow, or anything frozen); free from frost: »The sun at noon thaws the ice on the roads very quickly. SYNONYM(S): See syn. under melt. (Cf. ↑melt) …   Useful english dictionary

  • thaw — [thô] vi. [ME thawen < OE thawian, akin to Du dooien, Ger (ver)dauen, to digest < IE base * tā , to melt, dissolve, flow > L tabere, to melt, vanish] 1. a) to become liquid or semiliquid; melt: said of ice, snow, etc. b) to pass to an… …   English World dictionary

  • thaw — ► VERB 1) become or make liquid or soft after being frozen. 2) (it thaws, it is thawing, etc.) the weather becomes warmer and causes snow and ice to melt. 3) (of a part of the body) become warm enough to stop feeling numb. 4) make or become… …   English terms dictionary

  • thaw — haw, n. The melting of ice, snow, or other congealed matter; the resolution of ice, or the like, into the state of a fluid; liquefaction by heat of anything congealed by frost; also, a warmth of weather sufficient to melt that which is congealed …   The Collaborative International Dictionary of English

  • thaw — haw (th[add]), v. i. [imp. & p. p. {Thawed} (th[add]d); p. pr. & vb. n. {Thawing}.] [AS. [thorn][=a]wian, [thorn][=a]wan; akin to D. dovijen, G. tauen, thauen (cf. also verdauen to digest, OHG. douwen, firdouwen), Icel. [thorn]eyja, Sw. t[ o]a,… …   The Collaborative International Dictionary of English

  • thaw — thawless, adj. /thaw/, v.i. 1. to pass or change from a frozen to a liquid or semiliquid state; melt. 2. to be freed from the physical effect of frost or extreme cold (sometimes fol. by out): Sit by the fire and thaw out. 3. (of the weather) to… …   Universalium

  • thaw — thaw1 [ θɔ ] verb 1. ) thaw or thaw out intransitive or transitive if ice or snow thaws or something thaws it, it becomes warmer and changes into liquid: Thawing sea ice in the Arctic can trigger climate change. a ) intransitive or transitive if… …   Usage of the words and phrases in modern English

  • thaw — thaw1 [θo: US θo:] v [: Old English; Origin: thawian] 1.) also thaw out [I and T] if ice or snow thaws, or if the sun thaws it, it turns into water ≠ ↑freeze ▪ The lake thawed in March. 2.) it thaws if it thaws, the weather becomes warmer, so… …   Dictionary of contemporary English

  • thaw — I UK [θɔː] / US [θɔ] verb Word forms thaw : present tense I/you/we/they thaw he/she/it thaws present participle thawing past tense thawed past participle thawed 1) a) thaw or thaw out [intransitive/transitive] if ice or snow thaws, or if… …   English dictionary

  • thaw — [[t]θɔ[/t]] v. i. 1) to pass or change from a frozen to a liquid or semiliquid state; melt 2) to be freed from the physical effect of frost or extreme cold (sometimes fol. by out): Sit by the fire and thaw out[/ex] 3) mer (of the weather) to… …   From formal English to slang

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