From the SPC ...SYNOPSIS... A HIGHLY AMPLIFIED LARGE SCALE PATTERN WILL CONTINUE DURING THE PERIOD...HIGHLIGHTED BY A WEST/NORTHWARD SHIFTING UPPER RIDGE OVER THE GREAT BASIN/ROCKIES...AND A SLIGHT WESTWARD-RETROGRADING UPPER LOW OVER THE MIDWEST/LOWER OH VALLEY. ...UPPER OH VALLEY/APPALACHIANS TO THE EASTERN SEABOARD... GIVEN THE LARGE SCALE SCENARIO AS PREVIOUSLY DESCRIBED...THE NORTHEAST-SOUTHWEST ORIENTED FRONTAL ZONE ALONG THE APPALACHIANS WILL MOVE LITTLE TODAY...WITH A MOIST AIRMASS /NEAR 70 OR LOWER 70S F SURFACE DEWPOINTS/ REMAINING EAST OF THE APPALACHIANS. ALTHOUGH A BELT OF MODERATELY STRONG /25-40 KT/ SOUTH-SOUTHWESTERLY MID-LEVEL WINDS WILL REMAIN OVER THE REGION...UPPER HEIGHT RISES ARE ANTICIPATED ESPECIALLY EAST OF THE APPALACHIANS. EVEN SO...LOCALLY STRONG HEATING/DESTABILIZATION BOTH WEST/EAST OF THE APPALACHIANS SPINE WILL ALLOW FOR SOME STRONGER STORMS CAPABLE OF DOWNBURSTS...AND PERHAPS SOME HAIL ACROSS THE OH VALLEY...THIS AFTERNOON/EARLY EVENING. ADDITIONALLY...THE POTENTIAL FOR SOMEWHAT STRONGER SOUTHERLY LOW-LEVEL FLOW /30 KT AROUND 850 MB ESPECIALLY WITHIN 150 MILES OF THE ATLANTIC/ COULD ALLOW FOR TRANSIENT/BRIEF SUPERCELL STRUCTURES TODAY ACROSS PARTS OF PA/NJ TO SOUTHERN NY AND/OR ACROSS PORTIONS OF THE UPPER OH VALLEY TO THE EAST/NORTHEAST OF A WEAK SURFACE LOW. ALTHOUGH THE DEGREE OF DESTABILIZATION SHOULD REMAIN WEAK...A BRIEF TORNADO THREAT MAY BE POSSIBLE ASIDE FROM A MORE PROBABLE DOWNBURST POTENTIAL ACROSS A BROADER PART OF THE EASTERN CONUS
Posted on: Mon, 01 Jul 2013 12:59:06 +0000