US Weather Commentary

Location: New York
Author: Michael Schlacter
Date: Friday, August 18, 2006

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:

NAO and PNA teleconnections are set-up in an early-Autumn pattern so very temperate to even cool weather will be locked in for most locations for the entire 2nd-half of August. Remarkably, some locations could experience (this August) the very rare feat of hitting 100°F and still finishing the same month "Below Normal". With upper-level troughing setting up, another burst of hot weather remains very unlikely through the medium-range, 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 are ensuring 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:

Drought conditions from Mississippi to Florida are locally close to the severe levels across the Plains this Summer. Tropical moisture, Tropical Waves and Tropical Storms could help alleviate the dry surface conditions, but more apparent will be the Seasonable afternoon temperatures to close out August, associated with the East Trough/Negative NAO.
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:

The only real saving grace to the consistently above-normal Summer temperatures (for most of the Central corridor, and into the Prairies of Alberta, Saskatchewan and Manitoba), is that days (and their onslaught of solar radiation) are becoming noticeably shorter. Some late-Summer MCC's could still yield some localized drenching rains (for Nebraska, Iowa and Illinois), but this will do little to reverse the overall surface conditions for the region. Western Great Lakes and the Mississippi Valley States will temper down to more seasonable readings, being that much closer to the Eastern U.S. Trough.
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. Agrarian and Hydrological stresses have already approached this Summer, levels not witnessed since the infamous Summer of 1988.

South-Central:

Dallas TX and (Oklahoma City OK) are fulfilling ourSouth-Central heat warnings from this March, still having had only 1 day (2 days) this entire month not break 100°F! Only the coastal arc from Corpus Christi TX to Lake Charles LA had benefited from soil-moisture supported limits on afternoon temperatures, but this reprieve has already expired with Houston for example now breaking 95°F consistently.
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:

After 3 weeks of refreshing temperatures, subsidence and compressional warming (supported by a positive PNA teleconnection) will heat up the Northwestern States for the 2nd time this Summer. The Northern Rockies and High Plains will experience the most significant heat with 100°F being reached on a localized basis, but even coastal communities could see some double-digit positive temperature anomalies. Surface conditions have dramatically dried out from the Northern Rockies to the Pacific shoreline over the past 6 weeks so with ridging shifting West again, warm periods remain probable through the balance of 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:

Monsoonal patterns have departed most of the western deserts and are now concluding their run focused on New Mexico and far western Texas, where flash-flooding remains a concern. The westward-expanding ridging should push Riverside to over 100°F next week and perhaps Sacramento as well. Despite the warm Summer temperatures in Southern California, Santa Ana events have been practically non-existent this year, so we're still likely to max temperatures kept at or below 80°F for San Francisco, Los Angeles [LAX] 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:

Aircraft Recon investigations cancelled by NHC yesterday. (IM & Cell Phone participants will be notified as always of any official NHC declarations, before they are Publicly announced).

Despite inactions by NHC, Depression conditions should be experienced by Southeast Atlantic Coastal communities...

Gulf: Sea temperatures as a whole are above normal ranging from 84°F in isolated "cool" pockets to near 90°F along the U.S. Gulf coast. Wind Shear UNFAVORABLE. surface low in the Central Gulf of Mexico has minimal convection associated with it at this time. The wind shear will continue to increase and make development unlikely.

Bahamas/Sargasso Sea: Sea temperatures below normal to the South and near normal to the North with values ranging from 82°F near Bermuda to 90°F in the Western Bahamas. Wind Shear becoming UNFAVORABLE. The tail-end of the frontal boundary did develop a closed low-level circulation along with tropical convection yesterday, but the Hurricane Center inexplicably did not classify it as a Tropical Depression. Currently, the system remains borderline to being classified, but don't be surprised if NHC runs out the clock since destructive wind shear is less than 18 hours away.

Caribbean/far Atlantic: Sea temperatures near normal and much cooler than 2005. Temperatures range from 80°F just Northwest of the Cape Verdes and in the Central Caribbean, to near 88°F around both the Greater & Lesser Antilles and the Tropical Atlantic below 10°N. Wind Shear FAVORABLE. Two tropical waves are showing signs of unorganized convection at the moment but are still many days away from land.

Our research now strongly indicates that a Hemispheric and Tropospheric transition is under way that would ignite significant Atlantic Basin Tropical activity during the final 2 weeks of August.

The 4th or "D" Tropical Storm of the Season, climatologically forms on August 22nd.

Major Gulf-Impacting Hurricanes such as Andrew, Lili, Ivan, Katrina and Rita, all did so well after August 16th.

FYI: During the 2004 and 2005 Seasons, NHC declared the first classification of a tropical system in either their 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 (Historical Hurricanes Impacting New York):

<http://www.weather2000.com/NY_Hurricanes.html> http://www.weather2000.com/NY_Hurricanes.html

Forecasting the Forecast:

NWS finally came on board yesterday with widespread below normal temperatures East of the Mississippi. Very little should change in the wake of the new model guidance that they utilize, with cool temperatures in the East and warmth from the Northwest to the Northern Plains. The Southwest may have more areas of "no forecast" instead of the warm anomalies indicated in the 8-14 outlook.