US Weather Commentary

Location: New York
Author: Michael Schlacter
Date: Thursday, July 27, 2006

Coasts Cool as Central Experiences Draught

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

Seasonably temperate days and comfortable nights have been greeting Northeasterners this week, but humidity is gradually on the upswing. Extremely saturated ground plus long summer days of sunshine is a recipe for mugginess, cumulous cloudiness and thunderstorm formation (all of which models underestimate), so this should keep a cap on afternoon temperatures. Unlike the clear, dry, blue skies of the Summer's only technical heat wave (July 16th-18th), it will be very difficult this time around for a location like Manhattan to string together 3 days in a row breaking 90°F, before seasonable weather resumes again for the first week of August.
Humid evenings and bouts of mugginess need to be acknowledged and factored in, but routine frontal passages will help ensure that locations such as Detroit, Pittsburgh, Buffalo, Burlington, Hartford and New York, will have some of the largest reductions in cumulative Cooling Degree Days from Summer 2005 to Summer 2006 [June-September].

Southeast

On Sunday, Macon GA finally had its first day below 98°F since July 12th(!) but extreme drought across the Gulf Coast and Southeast States will easily propel this area back to above normal temperatures this week and especially next week. As highlighted last Wednesday, "the fly in the ointment may be a potential Tropical system forming in the Gulf of Mexico", and which could have downstream hydro-meteorological implications for the region.
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

Plains' temperatures are already soaring back to the 95°F - 105°F range for the final week of July, and this will continue into early August as substantial ridging once again gets re-centered over the contiguous 48 States. 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 Wisconsin, Minnesota, Iowa, North Dakota, South Dakota and Nebraska.
Parts of Illinois and Indiana need to be monitored for possible worsening and encroaching drought (approaching severe conditions currently present in IA, MO, MN, WI, SD and ND), and thus the potential for surface-enhanced heat-waves during the Summer.

South-Central

Locations across the region are finally enjoying more "normal" July heat this final week of the month, after Dallas TX rattled off 11 consecutive days cracking the 100°F mark. More anomalous heat will resume soon for the Southern Plains, Ozarks and Western Gulf Coast to kick-off August on a hot & steamy note As highlighted last Wednesday, "the fly in the ointment may be a potential Tropical system forming in the Gulf of Mexico", and which could have downstream hydro-meteorological implications for the region.
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

As we turn the corner on the final weekend of July, dramatically cooler temperatures (e.g. low 80's in Spokane, and even some 80's in Sacramento). will be in store for the same locations that achieved a freakish heat spike this past weekend (Seattle, WA = 97°F, Spokane WA = 102°F, Portland OR = 104°F, Sacramento = 111°F). A modest trough should linger over the entire Pacific coastal region for the first part of August in a similar fashion to the mild stretch the Pacific Northwest experienced July 10-19.
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

From Phoenix AZ to Las Vegas NV to Palm Springs CA to Burbank CA, the "desert communities" are holding up their Western end of the Horseshoe heat pattern. One expects desert microclimates to be hot in the middle of Summer, but impressive monthly anomalies of +3 to +6°F for July are sizzling even if you're used to it. They'll ease up on the "heat throttle" over the next 14 days where 'below normal' afternoons will become more numerous (e.g. 80's in Burbank, and even some 90's in Las Vegas).
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 Discussion

In addition to our more conversational commentary, we will also issue "Dash-Board" updates so you can efficiently gauge the 'what, where and when' of tropical entities of concern. Even more-immediate announcements, advisories and warnings will be disseminated via IM and/or cell phone.

WHAT: A Tropical Disturbance located near the extreme western Gulf of Mexico shoreline. As a reference reminder, if the system matures if would be T.D. # 3 and/or CHRIS. In contrast, we had our 7th named storm of the year by this date in 2005, but hadn't yet had our first named storm in 2004.

ODDS: Still disorganized, enduring moderate wind-shear, and having just drifted barely over Mexico, nothing will be happening immediately with this system. Since it could just as easily drift back over the Gulf waters our research maintains roughly 25% odds that the NHC could officially classify this system between now through Wednesday July 26th. We will update these odds as conditions warrant.

WHEN: As previously mentioned, disruptive wind-shear are keeping things very disorganized for the time being, but are in fact gradually relaxing today. NHC has no aircraft recon missions scheduled, but satellite and in-situ data could be used in lieu of recon if the disturbance abruptly organizes over the Gulf waters. {Sometimes tropical conditions mature faster than NHC scheduling, and NHC could skip over T.D. status and jump straight to a Tropical Storm declaration.}

WHERE: With hardly any organization, current vector motions have recently accelerated to Northward at 10 mph. It must be re-emphasized that if steering currents impart a vector heading just slightly east of North, the system will then have an extended time over 84°F-88°F waters as it parallels the Mexico/Texas coastline in the direction of Corpus Christi/Galveston.

HOW: At a minimum, this tropical system/complex will be unleashing copious amounts of moisture (drought-relieving rainfall & thunderstorms) either indirectly on southern Texas & Louisiana (via advection from Mexico), or directly (a scenario coastal Texas has become familiar with over the past 6 weeks). This will undoubtedly have hydro-meteorological (and by extension temperature) implications for Mexico, Texas, Louisiana and other downstream States, which our regional analysis anticipated last week, and will still factor in going forward.

All interests in, and bordering, the Western Gulf waters, Northeastern Mexico, Southern Texas, and the other Gulf Coastal States, should closely monitor the progress of this system.

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

Forecasting the Forecast:

Models are again in good agreement that a strong ridge will persist across the Central States and troughing will make its way into the Northwest and Northeast. Maps today should be similar to those issued yesterday, with the possibility of more Below normal coverage into the Mid-Atlantic. The Southwest remains a tricky area, with some models forecasting cooler than normal conditions and an active monsoon, so additional areas of "no forecast" may be added.