US Weather Commentary

Location: New York
Author: Michael Schlacter
Date: Wednesday, August 9, 2006
 

East and West Coasts enjoy refreshing August temperatures; more Heat for Mid-Con

For each U.S. region listed below, the first bullet-point will focus on medium-range comments (updated each discussion), while the second bullet-point will focus on Seasonal comments (updated as research warrants).

Northeast:
  • Seasonable pleasant weather has resumed for the Northeast quadrant States, and with High pressure in place we should witness some overnight temperatures dipping into the 40's across deep New England this week.  Remarkably, some locations could experience this August the very rare feat of hitting 100°F and still finishing the month "Below Normal".  With upper-level troughing setting up, another burst of hot weather remains very unlikely until the NAO flips to a positive phase.
  • Humid evenings and bouts still have to be eyed for the next 4 weeks, but routine frontal passages will help ensure that locations such as Detroit, Pittsburgh, Buffalo, Burlington, Hartford and New York, are having some of the largest reductions in cumulative Cooling Degree Days from Summer 2005 to Summer 2006 [June-September].

Southeast:
  • Thunderstorms and rains have remained isolated and infrequent, perpetuating drought conditions from Mississippi to South Carolina (Florida inclusive) close to the severe levels currently across the Plains.  As a result, Atlanta has only had 1 day this month below 96°F, but the Southeast will quickly succumb to the Negative NAO/Eastern Troughing, and cool off as well.
  • With (warmer) ridging extending eastward into the South at times, critical days (i.e. days > 90°F, 95°F, 100°F) are more numerous than in 2005, and with Hurricane Season upon us, substantial stresses on both the Agricultural and Energy Industries are likely.

North-Central:
  • Hot, above-normal, Summer temperatures continue like a broken record for most of the Central corridor, and into the Prairies of Alberta, Saskatchewan and Manitoba.  Some late-Summer MCC's could yield some localized drenching rains, but this will do little to alter the overall surface conditions for the region. Agrarian and Hydrological stresses are already approaching levels not witnessed since the infamous Summer of 1988, and very little precipitation relief is in sight for the most drought-stricken States of Minnesota, Iowa, North Dakota, South Dakota and Nebraska.
  • Parts of Illinois and Iowa need to be monitored for possible worsening and encroaching drought (approaching severe conditions currently present in MO, MN, SD, ND and NE), and thus the potential for surface-enhanced heat-waves during the Summer.

South-Central:
  • Dallas TX just finished rattling off another streak of 9 consecutive days topping 100°F, as (literal) scorched earth propels the AR-OK-TX zone to more blistering records.  Only the coastal arc from Corpus Christi TX to Lake Charles LA has benefited from soil-moisture supported limits on afternoon temperatures, but this reprieve may be expiring as they are quickly drying out as well, pending future tropical storms.
  • Being near the epicenter of our forecasted "Omega" or "Horseshoe" Summer pattern, these aforementioned States will be most consistently under the influence of ridging, subsidence and compressional warming, almost regardless of how the Hemispheric patterns oscillate this Summer.

Northwest
  • A modest trough has been lingering over the entire Pacific coastal region for the first part of August, with some atypical Summertime cloudiness, in a similar fashion to the mild stretch the Pacific Northwest experienced July 10-19.  Surface conditions have dramatically dried out from the Northern Rockies to the Pacific shoreline over the past 6 weeks some warm periods remain likely through mid-August.
  • The protection of moist surface conditions which much of the Northwest has enjoyed, is almost completely eroded and should become an issue deeper into the Summer whenever U.S. ridging skews westward, particularly away from the coast.

Southwest:
  • With ridging further East for the past 2 weeks, troughs and monsoonal clouds/moisture have correspondingly helped cool off some of the most scorching locales from July.  Monsoonal patterns have already winded down, so temperatures will consequently start to rebuild back to the 100's for the desert cities.  But Sacramento will be kept in the 90's during this medium-range period, along with mostly 70's for San Francisco, Los Angeles and even San Diego.
  • Westward oscillations of upper-air ridging along with interior drought versus coastal maritime influences, should make for quite a heterogeneous and chaotic Summer for the Southwest quadrant of the Nation.

Tropics Status:

Gulf: Sea temperatures as a whole are above normal ranging from 84°F in isolated "cool" pockets in the Bay of Campeche to over 90°F along the U.S. Gulf coast. Wind Shear UNFAVORABLE. The vestiges of Chris are now moving into Mexico near the Texas border.

Bahamas/Sargasso Sea: Sea temperatures below normal to the South and near normal to the North with values ranging from 82°F in pockets to 88°F in the Western Bahamas. Wind Shear UNFAVORABLE in most areas with some FAVORABLE conditions moving in a few days from now. The tail end of the frontal boundary that moved through the Mid-Atlantic last night has to be watched over the next several days, but elsewhere things are quiet.

Caribbean/far Atlantic: Sea temperatures near normal and much cooler than 2005. Temperatures range from near 80°F around the Cape Verdes and Central Caribbean, to near 86°F around both the Greater and Lesser Antilles. Wind Shear UNFAVORABLE in the Caribbean, but becoming more FAVORABLE in a few days and generally FAVORABLE in the Central Atlantic. The African dust layer has been persistent over the last month and is helping to keep the Tropics relatively dry, but is expected to diminish considerably in the weeks ahead. The Atlantic Ocean low pressure system we have been eyeing is waxing and waning every few hours but has the potential to develop into T.D. #4 (and subsequently Tropical Storm Debby), as it moves towards the Windward Islands.  We will next update you if and when NHC classification becomes imminent.

Note: During the 2004 and 2005 Seasons, NHC declared the first classification of a tropical system in either the 5 PM or 11 PM advisory periods an imbalanced 65% of the time, and outside of the work day (i.e. weeknights, weekends) an imbalanced 79% of the time.

Related link of interest (re: NY Hurricane threats):  http://www.weather2000.com/NY_Hurricanes.html

Forecasting the Forecast:

Look for the NWS to continue its low confidence outlooks, with many areas of "no forecast." One area that seems pretty certain is in the West, where yesterday's 8-14 day forecast should repeat itself. Below normal conditions or "no forecast" is almost certain along the Eastern Seaboard and New England, while some Midwest warmth should be indicated.

To subscribe or visit go to:  http://www.riskcenter.com/