1WTNT43 KNHC 221503 2TCDAT3 3TROPICAL DEPRESSION THREE DISCUSSION NUMBER 1 4NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032010 51100 AM EDT THU JUL 22 2010 6 7THE TROPICAL WAVE/DISTURBANCE THAT NHC HAS BEEN TRACKING FOR THE 8PAST SEVERAL DAYS ACROSS THE ATLANTIC HAS DEVELOPED A SURFACE 9CIRCULATION AND ENOUGH ORGANIZED CONVECTION TO BE CLASSIFIED AS A 10TROPICAL DEPRESSION. THE DEPRESSION IS SHEARED AT THIS TIME AND ITS 11CENTER IS LOCATED ON THE SOUTHWEST SIDE OF A CYCLONICALLY CURVED 12CONVECTIVE BAND. THE SHEAR APPEARS TO BE RELAXING A 13LITTLE...HOWEVER...AS INDICATED BY THE MOTION OF THE HIGH CLOUDS ON 14HIGH RESOLUTION IMAGES. THE CYCLONE IS STILL INTERACTING WITH A 15STRONG WESTWARD-MOVING UPPER LOW TO THE WEST. THIS PATTERN WOULD 16ONLY ALLOW THE DEPRESSION TO STRENGTHEN A LITTLE AS INDICATED IN 17THE OFFICIAL FORECAST...BUT THIS FORECAST IS UNCERTAIN. IN FACT... 18NONE OF THE MODELS SHOW SIGNIFICANT INTENSIFICATION. 19 20BECAUSE THE CENTER JUST FORMED...THE INITIAL MOTION IS UNCERTAIN. 21THE BEST ESTIMATE IS TOWARD THE WEST-NORTHWEST OR 295 DEGREES AT 13 22KNOTS. GLOBAL MODELS FORECAST A WELL-ESTABLISHED SUBTROPICAL RIDGE 23EXTENDING FROM THE ATLANTIC WESTWARD ACROSS THE SOUTHERN UNITED 24STATES. THIS STEERING PATTERN SHOULD KEEP THE CYCLONE ON A GENERAL 25WEST-NORTHWESTWARD TRACK THROUGH 3 TO 4 DAYS ACROSS THE FLORIDA 26STRAITS AND THE KEYS AND THEN INTO THE GULF OF MEXICO. BECAUSE THE 27RIDGE IS FORECAST TO STRENGTHEN...THE CYCLONE SHOULD BEGIN TO 28INCREASE ITS FORWARD SPEED. THE TRACK GUIDANCE IS TIGHTLY CLUSTERED 29THROUGH 4 OR 5 DAYS...ALTHOUGH SOME MODELS WEAKEN THE CYCLONE 30EARLIER. 31 32AN AIR FORCE PLANE WILL BE IN THE AREA THIS AFTERNOON AND WILL HELP 33TO DETERMINE IF THE SYSTEM HAS BECOME A TROPICAL STORM. 34 35 36FORECAST POSITIONS AND MAX WINDS 37 38INITIAL 22/1500Z 21.9N 75.0W 30 KT 39 12HR VT 23/0000Z 22.6N 76.8W 35 KT 40 24HR VT 23/1200Z 23.8N 80.0W 40 KT 41 36HR VT 24/0000Z 25.0N 83.2W 40 KT 42 48HR VT 24/1200Z 26.0N 86.5W 40 KT 43 72HR VT 25/1200Z 28.0N 91.5W 45 KT 44 96HR VT 26/1200Z 31.0N 94.0W 25 KT...INLAND 45120HR VT 27/1200Z 33.0N 95.0W 20 KT...POST-TROP/REMNT LOW 46 47$$ 48FORECASTER AVILA/ROBERTS 49 50 51WTNT43 KNHC 222032 52TCDAT3 53TROPICAL DEPRESSION THREE DISCUSSION NUMBER 2 54NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032010 55500 PM EDT THU JUL 22 2010 56 57AN AIR FORCE RECONNAISSANCE PLANE HAS BEEN INVESTIGATING THE 58DEPRESSION AND FOUND A BROAD CIRCULATION WITH PEAK WINDS AROUND 30 59KNOTS AND A MINIMUM PRESSURE NEAR 1006 MB. THE CLOUD PATTERN HAS NOT 60BECOME ANY BETTER ORGANZIED THAN EARLIER TODAY WITH THE CENTER NOW 61ON THE SOUTHERN PORTION OF THE CONVECTION DUE TO SOME SHEAR. THE 62OUTFLOW IS BECOMING ESTABLISHED IN ALL QUADRANTS EXCEPT TO THE 63SOUTHWEST WHERE THE UPPER LOW IS LOCATED. INITIAL INTENSITY IS KEPT 64AT 30 KNOTS BUT ONLY A SMALL RELAXATION OF THE SHEAR...AS 65EXPECTED...WILL RESULT IN SOME INTENSIFICATION. NONE OF THE 66GUIDANCE MODELS SHOW LARGE INCREASES IN STRENGTH...PERHAPS DUE TO 67THE PROXIMITY OF THE DEPRESSION TO THE STRONG UPPER LOW. THE 68OFFICIAL FORECAST IS GENEROUS COMPARED TO THE DYNAMICAL GUIDANCE 69BUT IS CLOSE TO THE SHIPS AND LGEM MODELS. 70 71THE OVERALL CIRCULATION HAS MOVED A LITTLE TO THE NORTHWEST AROUND 72AN UPPER-LOW OVER FLORIDA DURING THE PAST FEW HOURS. THE BEST 73ESTIMATE OF THE INITIAL MOTION IS 310 DEGREES AT 12 KNOTS. 74HOWEVER...AS THE UPPER LOW MOVES TO THE WEST AS INDICATED BY MOST 75OF THE GLOBAL MODELS...THE DEPRESSION WILL BECOME EMBEDDED WITHIN A 76DEEP EASTERLY FLOW AND SHOULD BEGIN TO MOVE MORE TO THE 77WEST-NORTHWEST WITH AN INCREASE IN FORWARD SPEED. THE TRACK 78GUIDANCE IS IN REMARKABLY GOOD AGREEMENT...BRINGING THE CYCLONE 79ACROSS THE FLORIDA STRAITS AND ACROSS THE GULF OF MEXICO...AND 80SO DOES THE OFFICIAL FORECAST. 81 82 83FORECAST POSITIONS AND MAX WINDS 84 85INITIAL 22/2100Z 22.7N 75.4W 30 KT 86 12HR VT 23/0600Z 23.8N 77.5W 35 KT 87 24HR VT 23/1800Z 24.5N 80.5W 45 KT 88 36HR VT 24/0600Z 25.5N 83.7W 45 KT 89 48HR VT 24/1800Z 26.5N 86.5W 45 KT 90 72HR VT 25/1800Z 29.0N 91.0W 45 KT 91 96HR VT 26/1800Z 32.5N 93.0W 25 KT...INLAND 92120HR VT 27/1800Z 34.5N 93.0W 20 KT...POST-TROP/REMNT LOW 93 94$$ 95FORECASTER AVILA/ROBERTS 96 97 98