SOUTHEAST ARIZONA FORECAST DISCUSSION...MESOSCALE UPDATE NATIONAL WEATHER SERVICE TUCSON AZ 618 PM MST THU AUG 16 2001 .SYNOPSIS...HIGH PRESSURE WILL BUILD IN FROM THE WEST THE NEXT FEW DAYS. THE RESULTING FLOW PATTERN WILL DIMINISH THUNDERSTORM COVERAGE...ESPECIALLY OVER THE WESTERN DESERTS...WITH DRIER AIR TO THE NORTH AND DEEPER MOISTURE IN NORTHERN MEXICO. BY EARLY NEXT WEEK...THE HIGH MOVES EAST OF ARIZONA AND THE FLOW BECOMES FAVORABLE FOR A RETURN TO NORMAL THUNDERSTORM ACTIVITY. .DISCUSSION...SEVERAL STORM CLUSTERS CONTINUE TO MOVE GENERALLY SW TOWARD KTUS FROM COCHISE/GRAHAM COUNTIES. CELL ORGANIZATION HAS BEEN LOOSE, PULSEY, AND OUTFLOW DOMINATED SO FAR. 00Z KTUS SOUNDING IS SURPRISINGLY STABLE (CAPE AROUND 900 J/KG) WITH A CAP AT 500MB. THE ONE TROUBLING THING I SEE IS THAT OUR BOUNDARY LAYER IS VERY DEEP AND RATHER DRY. INVERTED-V EXTENDING UP TO 600MB RAISES A RED FLAG FOR MICROBURSTS AS THE STORMS STRUGGLE TO MOVE INTO THE SANTA CRUZ VALLEY THROUGH 8 PM. TSTMS HAVE RECENTLY WEAKENED IN W COCHISE COUNTY AS THEY HIT MORE STABLE AIR. LAPS DATA FROM 00Z SHOWS THE HIGHEST CAPES OVER EASTERN PINAL AND SANTA CRUZ COUNTIES, BOTH OF WHICH CLEARED OUT A LITTLE EARLIER THIS AFTERNOON. HOWEVER, THE 21Z RUC INDICATES SOME MID LEVEL COOLING WITHIN THE NEXT 3-6 HRS AS UPPER LEVEL DIVERGENCE INCREASES OVER SE AZ. THERE ARE ALSO SEVERAL OUTFLOW BOUNDARIES NOW MOVING TOWARD THE AREA, A COUPLE OF WHICH ARE GOING TO COLLIDE BASED ON WSR-88S LOOPS. IN SUMMARY, ANY STORMS WHICH CAN DEVELOP OVER PINAL, EASTERN PIMA, AND SANTA CRUZ COUNTIES WILL HAVE THE POTENTIAL TO PRODUCE MICROBURSTS OVER THE NEXT SEVERAL HOURS. HOWEVER, COVERAGE WILL BE ISOLATED THANKS TO OUR SOMEWHAT LIMITED CAPES. PYTLAK .TWC...NONE. az AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1035 AM EDT THU AUG 16 2001 FCST CONCERN THIS AFTN IS SHRA COVERAGE. WV IMAGERY SHOWS STRONG SHORTWAVE DROPPING SE INTO NW WI...WITH A WEAK SHORTWAVE LIFTING NE INTO LWR MI. NICE UPPER DIFFLUENCE PATTERN DEVELOPING AHEAD OF NW WI SHORTWAVE AS RADAR SHOWS SHRA FANNING OUT NWD THRU ERN WI INTO UPPER MI. AT THE SFC...ONE LOW WAS NEAR KP59 WHILE A SECOND LOW WAS JUST S OF KMKE. AFTER THE FRUSTRATION OF TRYING TO GET SHRA IN HERE YESTERDAY... FCST THIS AFTN IS STRAIGHTFORWARD. SHORTWAVE IN NW WI WILL DRIFT SE THIS AFTN TWD KMNM PER 12Z RUC...PROVIDING MDT/STRONG QVEC CONVERGENCE AND FAVORABLE UPPER DIFFLUENCE PATTERN OVER FA... ESPECIALLY E HALF. GIVEN DEEP MOIST AIRMASS (12Z KGRB SOUNDING SHOWS DWPT DEPRESSIONS OF 5C OR LESS THRU 500MB)...CONTINUED FORCING FOR LARGE SCALE UVM...AND EXPANSIVE NATURE OF SHRA PER CURRENT RADAR IMAGERY...EXPECT GOOD COVERAGE OF SHRA ALL AFTN OVER FA...ESPECIALLY E HALF OR SO. TSRA THREAT APPEARS VERY MINIMAL. UPSTREAM KGRB SOUNDING SHOWS UNIMPRESSIVE LAPSE RATES AS TEMP PROFILE IS MOIST ADIABATIC. MODIFICATION OF SOUNDING FOR TEMPS IN THE UPPER 60S (WHICH IS A BIT OPTIMISTIC) ONLY YIELDS CAPES AROUND 300J/KG. WILL FURTHER DOWNPLAY TS THREAT ON UPDATE. THICK CLOUD COVER/SHRA WILL GENERALLY KEEP TEMPS FROM RISING MORE THAN A FEW DEGREES FROM CURRENT READINGS .MQT...NONE. ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON, NC 1015 PM EDT THU AUG 16 2001 MESO-ETA AND RUC TO A CERTAIN DEGREE INDICATES WEAK UVVS ACROSS THE COASTAL COUNTIES DURING THE OVERNITE PERIOD. RUC IS SHOWING A WEAK INVERTED SFC TROF JUST OFF THE COAST...MESO-ETA TO A LESSER DEGREE...WARRNANTING SCT TO OCCASIONAL BKN LOW TO MID LEVEL CLDS. WILL CHANGE SKY CONDITIONS TO BECOMING PTLY CLDY ALONG THE IMMEDIATE COAST. SHULD SEE PATCHY GROUND FOG...HOWEVER NOT WIDESPREAD ENOUGH TO PLACE IN THE FORECAST. TEMPS...PERSISTENCE FROM LAST NIGHTS MINS WITH ONLY SLIGHT MODERATION FROM ONSHORE FLOW THAT WORKED ITS WAY ACROSS THE FA. CURRENT FCST TEMPS LOOK IN THE BALLPARK EXCEPT WILL TWEAK SLITELY LOWER INLAND. CWF...WEAK INVERTED SFC TROF JUST OFF THE NORTHEAST SC COAST AND SOUTHEAST NC COAST OVERNIGHT GETS ABSORBED IN THE MEAN FLOW EARLY FRIDAY. WILL INITIALIZE WIND DIR FROM THE EAST 10-15 KTS TO ACCOUNT THE TROF ACTION. SEAS 3-4 FT. FCSTID = 11 ILM 71 91 75 89 / 0 20 40 40 LBT 68 92 72 90 / 0 20 40 40 FLO 69 93 73 91 / 0 20 40 40 MYR 72 88 76 87 / 0 20 40 40 .ILM... NC...NONE. SC...NONE. DCH nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1030 AM EDT THU AUG 16 2001 ...WILL UPDATE TO TWEAK POPS AND TEMPS... 11Z SURFACE ANALYSIS SHOWS STORM SYSTEM IN MIDWEST WITH SURFACE LOW OVER CHICAGO. VAD WIND PROFILE SHOWS 20-30 KNOT SOUTH-SOUTHWESTERLY FLOW FROM 3-20 KFT. 12Z PIT AND BUF SOUNDINGS SHOWS DISTINCT DIFFERENCE ACROSS THE REGION. PIT SHOWS WARM MOIST LOW LEVEL AFTER MIXING...WHILE BUF WILL BE DRIER AFTER MIXING. LOOKS TO BE A WARM FRONT FORMING OVER OUR WESTERN COUNTIES AT THIS TIME ON THE VISIBLE SATELLITE IMAGERY. DRY LAYER IN THE MIDLEVELS NOTED FROM PIT SOUNDING WILL HELP TO DESTABILIZE THE AREA THIS AFTERNOON AND EVENING. MIXING WILL STRENGTHEN THIS FRONT DURING THE AFTERNOON HOURS. EXPECT SUNSHINE IN THE AFTERNOON WITH SCATTERED CONVECTION FIRING...WHICH IS ALREADY OCCURRING BACK IN WEST VIRGINIA AND SOUTHEAST OHIO. RUC40 SHOWS DECENT 925MB MOISTURE CONVERGENCE OVER OUR CENTRAL COUNTIES THIS AFTERNOON WITH -5 TO -10 UBAR/S 850MB VERTICAL VELOCITIES. MAIN ACTION WILL BE TONIGHT AS THE SHORTWAVE DROPS ACROSS THE UPPER MIDWEST. AS THIS OCCURS...THE 850MB JET IS PROGGED TO INCREASE OUT OF THE SOUTHWEST. WIND PROFILE WILL BE STRONG AND VEERING. CONCERN TONIGHT IS HELICITY VALUES PROGGED AT OVER 300 M2/S2. BEST CHANCE FOR SEVERE WEATHER REMAINS IN THE WESTERN COUNTIES LATE THIS AFTERNOON INTO THIS EVENING...AND WILL REISSUE SEVERE WEATHER OUTLOOK. .CTP...SEVERE WEATHER OUTLOOK FOR WESTERN COUNTIES. ROGOWSKI/RXR pa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 950 PM EDT THU AUG 16 2001 COVERAGE OF SHOWERS IN PRE-FRONTAL CONVERGENCE ZONE ACROSS CENTRAL TN IS NOT TREMENDOUS THIS EVENING. ISOLATED CONVECTION ASSOCIATED WITH THE 30 KT 850 MB JET SHOWING UP ON 00Z UPPER AIR ANALYSIS... HOWEVER...CONTINUES TO FIRE AHEAD OF THE MAIN PRECIP AREA. WITH LATEST RUC SHOWING FRONTAL ZONE PUSHING TO FAR WRN CWA BORDER BY 12Z...WILL HOLD ONTO CHC POPS FOR MTN ZONES OVERNIGHT. MESO ETA SOUNDING HOLDS ONTO 1500 CAPES NEAR AVL AT 06Z TONIGHT WITH AN IMPROVING SHEAR PROFILE...BUT COVERAGE AND FORCING APPEAR WEAK. WILL ISSUE UPDATE TO TWEAK NC PIEDMONT TEMPS DOWN A CATEGORY SINCE DEWPOINTS ARE IN THE 60S AND TEMPS ARE RUNNING BELOW MOS THROUGH 01Z. WILL ALSO CLEAN UP MIDNIGHT WORDING ELSEWHERE. FCSTID = 33 GSP 70 87 70 89 / 10 30 30 30 AND 70 87 70 89 / 10 30 30 30 CLT 69 87 69 88 / 10 30 30 30 HKY 67 85 66 86 / 10 30 30 30 AVL 65 82 65 85 / 40 40 30 30 .GSP... GA...NONE. NC...NONE. SC...NONE. HG sc AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 815 PM THU AUG 16 2001 02Z SURFACE ANALYSIS PUT NEW COLD FRONT ACROSS NORTHERN MT/ND ASSOCIATED WITH SHORTWAVE RACING SOUTHEAST OUT OF CANADA PER WATER VAPOUR. WEAK WY SHORTWAVE SUSTAINING -SHRA AFTER DARK...00Z RUC SUPPORTS WANING PRECIPITATION WITH THIS WAVE. IT ALSO SUPPORTS A CHANCE OF -SHRA AFTER 06Z WITH THE COLD FRONT...WHICH SHOULD MAKE IT TO KRAP AROUND 12Z. WILL SPRUCE UP THE CURRENT FORECAST TO ACCOUNT FOR THESE THOUGHTS. .UNR...NONE. HELGESON sd AREA FORECAST DISCUSSION...UPDATED FOR AVIATION NATIONAL WEATHER SERVICE FORT WORTH TX 1125 AM CDT THU AUG 16 2001 ...AVIATION DISCUSSION... VFR NEXT 24 HOURS WILL MAINLY MID AND HIGH LEVEL CLOUDINESS LINGERING AROUND THE AIRPORTS. SURFACE FRONT ACROSS SOUTHERN OK WILL KEEP WIND FLOW LIGHT AND VARIABLE AT TIMES...WITH JUST A SLIGHT TREND TOWARD A SE FLOW AROUND 5 KNOTS THROUGH THIS AFTERNOON. WIND FLOW TO BECOME MORE SOUTHERLY TOWARD MORNING. FRONTAL BOUNDARY MAY NOT MAKE IT MUCH FURTHER SOUTH...SO THUNDER CHANCES WILL BE LIMITED TO LATE THIS AFTERNOON/EVENING AS WEAK UPPER LEVEL LIFT ARRIVES. WILL LEAVE PRECIP AND THUNDER OUT OF TAFS ATTM. 80 1037 AM PUBLIC DISCUSSION... FRONTAL BOUNDARY EXTENDS FROM SOUTHEAST OKLAHOMA SOUTHWESTWARD INTO WEST-CENTRAL TEXAS. LATEST RUC MOVES THE BOUNDARY SLOWLY SOUTH ACROSS THE FORECAST AREA THIS AFTERNOON. EFFECTIVE BOUNDARY MAY BE DISPLACED SOUTH OF FRONTAL POSITION DUE TO OUTFLOW FROM OVERNIGHT CONVECTION. MORNING RAOB AT FWD SHOWED SIGNIFICANT MODIFICATION/ STABILIZATION FROM LAST NIGHT'S STORMS...INDICATING THAT THE MAIN THREAT FOR NEW DEVELOPMENT WILL LIKELY BE SOUTH OF THE METROPLEX THIS AFTERNOON/EVENING. WITH THAT IN MIND HAVE DECREASED THE POPS SLIGHTLY ACROSS THE NORTHERN TIER. WIDESPREAD CLOUD COVER WILL REDUCE DIABATIC HEATING...SO HAVE LOWERED MAX TEMPERATURES ALL AREAS EXCEPT SOUTHEAST. .FWD...NONE. 09 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 1037 AM CDT THU AUG 16 2001 FRONTAL BOUNDARY EXTENDS FROM SOUTHEAST OKLAHOMA SOUTHWESTWARD INTO WEST-CENTRAL TEXAS. LATEST RUC MOVES THE BOUNDARY SLOWLY SOUTH ACROSS THE FORECAST AREA THIS AFTERNOON. EFFECTIVE BOUNDARY MAY BE DISPLACED SOUTH OF FRONTAL POSITION DUE TO OUTFLOW FROM OVERNIGHT CONVECTION. MORNING RAOB AT FWD SHOWED SIGNIFICANT MODIFICATION/ STABILIZATION FROM LAST NIGHT'S STORMS...INDICATING THAT THE MAIN THREAT FOR NEW DEVELOPMENT WILL LIKELY BE SOUTH OF THE METROPLEX THIS AFTERNOON/EVENING. WITH THAT IN MIND HAVE DECREASED THE POPS SLIGHTLY ACROSS THE NORTHERN TIER. WIDESPREAD CLOUD COVER WILL REDUCE DIABATIC HEATING...SO HAVE LOWERED MAX TEMPERATURES ALL AREAS EXCEPT SOUTHEAST. .FWD...NONE. 09 tx SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 241 AM MST FRI AUG 17 2001 .SYNOPSIS... AN UPPER-AIR DISTURBANCE MOVING SOUTH ACROSS SOUTH-CENTRAL ARIZONA TRIGGERED SCATTERED THUNDERSTORMS LAST EVENING AND THIS MORNING. THIS DISTURBANCE WILL CONTINUE SOUTHWARD AS HIGH PRESSURE BUILDS IN FROM THE WEST OVER SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA. THE AIR WILL DRY A LITTLE AS THE HIGH PRESSURE MOVES OVER THE AREA... BUT NOT ENOUGH TO COMPLETELY STOP POSSIBLE AFTERNOON AND NIGHTTIME THUNDERSTORMS...MAINLY OVER THE HIGHER TERRAIN IN SOUTH-CENTRAL ARIZONA...THROUGH SATURDAY. A BETTER CHANCE FOR STORMS WILL EXIST ACROSS SOUTHWEST AND SOUTH-CENTRAL ARIZONA SUNDAY AND MONDAY AS A DISTURBANCE MOVES NORTHWESTWARD ACROSS THE AREA. THE HIGH PRESSURE AREA IS FORECAST TO MOVE SOUTH OF THE REGION EARLY NEXT WEEK... LEADING TO SOMEWHAT DRIER CONDITIONS AND LOWER TEMPERATURES. .DISCUSSION... UPPER-AIR DISTURBANCE CAUSING A RUCKUS AS IT TRIGGERED THUNDERSTORMS ACROSS S-CNTRL AZ LATE LAST EVE AND THIS MORNING UNDER DIFLUENT FLOW PATTERN ASSOCIATED WITH COL AT H3. ALL CAME TOGETHER OVER S-CNTRL AZ AT THE RIGHT TIME. DISTURBANCE APPEARS TO BE CONTINUING SWD...WITH STORMS SOON TO CLEAR THE PHOENIX METRO AREA. HIGH PRESSURE EXPECTED TO BUILD IN FROM THE W...BUT STEERING FLOW TO REMAIN OFF THE HIGHER TERRAIN TO THE N. THEREFORE...WILL STAY WITH MOS GUIDANCE OF 20 PCT POPS FOR TOMORROW NIGHT FOR THE PHOENIX METRO AREA...BUT IN GENERAL WILL STAY PRETTY CLOSE TO THE PREVIOUS FORECAST. GETTING HOTTER AS HIGH BUILDS IN...BUT WILL NOT GO QUITE AS HOT AS PREVIOUS FORECAST ...AS EXPECT SFC RH TO REMAIN PRETTY HIGH...AS NOTHING MUCH TO SCOUR IT OUT. ETA AND AVN MODELS FORECAST SE AZ DEFORMATION ZONE TO MOVE A LITTLE FARTHER N TODAY...TO A POSITION FAVORING MORE AFTERNOON AND EVENING CONVECTION OVER THE ERN MOGOLLON RIM AND WHITE MOUNTAINS. H5 NELY STEERING CURRENTS...AND SOME COOL ADVECTION AT H5 TO REINFORCE CAPE OVER THE DESERTS...SHOULD LEAD TO STORMS MOVING OR PROPAGATING TOWARD THE LOWER DESERTS EARLY THIS EVENING. FOR WHAT IT IS WORTH ...ETA SEEMED TO CAPTURE THE IMPULSE TRIGGERING STORMS THIS MORNING BETTER THAN DID THE AVN. AS FOR THE EXTENDED...WILL LEAVE IT AS IS FOR NOW. WILT az AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON 325 AM EDT FRI AUG 17 2001 KLWX RADAR SHOWING ONLY SOME WIDELY SCATTERED LIGHT PRECIP ALONG AND WEST OF THE BLUE RIDGE AT TIME. MORE SCATTERED PRECIP SHOWING UP ON KCCX/KPBZ/KRLX RADARS FROM CENTRAL PA THROUGH WESTERN WV. 06Z ANALYSIS PLACES COLD FRONT OVER EASTERN OHIO... WITH SCATTERED PRECIP A LITTLE BIT AHEAD OF FRONT. 00Z ETA AND 06Z RUC BRING THIS FRONT INTO THE WESTERN SECTIONS OF THE FA BY LATE MORNING... WITH ETA PUSHING FRONT THROUGH THE EAST BY LATE AFTERNOON. EXPECT A BAND OF SCATTERED PRECIP TO CONTINUE OUT AHEAD OF THE FRONT STABILITY INDICES APPEAR FAVORABLE FOR SOME SCATTERED SHOWERS AND STORMS... BUT MAIN DYNAMIC LIFT AND WIDESPREAD PRECIP SHOULD BE TO THE NORTH OF US. ETA/RUC SHIFT WINDS FROM THE SURFACE TO 850 TO THE WEST/SOUTHWEST BY EARLY AFTERNOON. RESULTING DOWNSLOPE AND DRYING SHOULD BRING AN END TO ANY PRECIP IN THE WESTERN HALF OF THE AREA BY AROUND 18Z... AND WILL WORD ACCORDINGLY IN THE ZONES. CLEARING SKIES BY MID AFTERNOON FROM IAD/CHO WEST ALONG WITH DOWNSLOPE SHOULD PUSH TEMPS UP CLOSE TO 90. A LITTLE COOLER IN THE EAST AS CLOUDS AND SCATTERED PRECIP HOLD ON A BIT LONGER. WEAK HIGH BUILDING INTO THE AREA OVERNIGHT WITH FAIRLY SUBSTANTIAL DRYING AT THE SURFACE ON BOTH ETA AND AVN. WILL LIKELY UNDERCUT MOS TEMPS BY A FEW DEGREES IN FAVORED COOLER AREAS. SATURDAY LOOKS QUIET WITH ONLY SOME UPPER LEVEL MOISTURE TO CONTEND WITH. FRONT APPEARS TO MAKE A RETURN NORTHWARD BY LATE SATURDAY NIGHT... AS UPPER LEVEL ENERGY DIVES DOWN FROM THE NORTHWEST. AVN TRYING TO BUMP UP TIMING OF PRECIP A LITTLE BIT... BUT 60 HR ETA FORECAST STILL HAS PRECIP JUST TO THE WEST. WILL NOT STRAY FROM TIMING OF CURRENT FORECAST... WITH PRECIP IN THE SUNDAY PERIOD. HIGH PRESSURE BUILDING IN FOR THE MIDDLE OF NEXT WEEK SHOULD RESULT IN DRY AND SEASONABLE CONDITIONS. DCA 89 68 86 70 / 30 10 0 20 BWI 89 65 86 67 / 30 10 0 20 MRB 88 58 85 63 / 30 0 0 20 IAD 89 61 86 67 / 30 0 0 20 CHO 89 62 86 68 / 30 0 0 20 HGR 88 59 84 65 / 30 0 0 20 NHK 87 70 84 71 / 30 10 0 20 W99 89 62 87 65 / 30 0 0 20 .LWX... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARGRAF! md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 420 AM EDT FRI AUG 17 2001 00Z RAOBS/LATEST WV LOOP AND RUC ANAL SHOW MEAN TROF OVR THE GREAT LAKES E OF HI AMPLITUDE WRN RDG. MAJOR SHRTWV OVR THE CNTRL LKS MOVG EWD AS H3 JET HAS ROUNDED BASE OF TROF AND PULLING SHRTWV E. NXT KICKER SHRTWV LOOKS FAIRLY VIGOROUS AND DROPPING S THRU MB ON ERN FLANK OF UPR RDG. DESPITE LINGERING LLVL CNVGC ARND SFC LO TO E OF ANJ...CLD TOP TEMPS IN WRAP ARND INCRSG AS H7-3 QVECTOR CNVGC/H4-2 DVGC PULLING OFF TO E WITH UPR LO. 88D LOOP SHOWS REFLECTIVITY/COVG OF ECHOES STEADILY DCRSG. LO CLD LINGERING IN CYC FLOW ON WRN FLANK OF SFC LO...BUT APRCH OF SFC RDG AXIS HAS BROUGHT CLRG TO IWD. SOME FOG DVLPD THERE AFTR SKIES CLRD WITH DWPTS STILL IN 50S. CLDS AHD OF MB SHRTWV NOW IN WRN ONTARIO...BUT FAIRLY DRY/STABLE MID TROP DEPICTED ON 00Z YPL SDNG (KINX 16) RESTRICTING PCPN TO SCT SHRA. FOR TDAY...MODELS IN GOOD AGREEMENT SHOWING SHRTWV/SFC LO OVR CNTRL LKS MOVG QUICKLY EWD WITH KICKER SHRTWV OVR MB DROPPING FARTHER S AND W THEN EARLIER FCST...A TREND CONSISTENT WITH STRENGTH OF WRN RDG. XCPT FOR SCT -SHRA OVR THE ERN ZNS EARLY...XPCT PCPN ASSOCIATED WITH FIRST SHRTWV TO HAVE ENDED OVR CWA BY ZN ISSUANCE. THEN SFC AND UPR RDGING/AXIS OF DRIER AIR ALF TO DOMINATE UNTIL LATE IN THE DAY...WHEN SFC TROFFING AHD OF CAN SHRTWV APRCHS WRN ZNS. FIRST ORDER OF BUSINESS IS TO DETERMINE TIMING OF CLRG OF CYC FLOW LO CLD. CLRG LINE NOW APRCHG IWD CORRELATES WELL WITH BACK EDGE OF CYC FLOW...AND THIS AXIS FCST TO SPRD STEADILY W-E TDAY... REACHING ERN ZNS EARLY THIS AFTN. ONCE SUN COMES OUT...XPCT CU TO REDVLP WITH SFC DWPTS WELL INTO 50S UNDER H85 THERMAL TROF (AVN/ETA SHOW H85 TEMP 9C OVR E TO 12C OVR W BY 00Z) JUST BLO SUBSIDENCE INVRN FCST ARND 6K FEET IN GOOD AGREEMENT WITH UPSTREAM 00Z SDNGS. VIS PIX FM YDAY SHOW EXTENSIVE CU FIELD DVLPD UPSTREAM THU AFTN. UPSTREAM MAX TEMPS YDAY WELL IN 70S AND UPSTREAM SDNGS SHOW WELL MIXED BLYR...SO WL TEND TOWARD HIER MAV GUIDANCE FOR MAX TEMPS...FWC TEMPS ARE RUNNING TOO LO ATTM. CONSIDERING XPCTD FULL MIX TO H85...PREVIOUS FCST MAX AS HI AS THE UPR 70S ACRS THE INTERIOR SW LOOK OKAY. MODELS PERSIST ON GENERATING PCPN OVR FAR WRN ZNS BY 00Z WITH ETA/NGM SHOWING WEAK SFC TROFFING/LLVL MSTR CNVGC IN THIS AREA AS H85-3 QVECTOR CNVGC ARRIVES BY 00Z. MESOETA FCST SDNG FOR IWD AT 21Z WITH T/TD OF 77/56 INDICATES 1100 J/KG AS UPR DYNAMICS BEGIN TO WEAKEN SUBSIDENCE INVRN. GIVEN POTENTIAL FOR LK BREEZE CNVGC WITH WEAK SW GRADIENT FLOW...WL OPT TO MAINTAIN MENTION OF SHRA/TSRA. BUT FCST 25 KINX SHUD LIMIT COVG TO SCT. AS STRG SHRTWV DIGS TO NEAR MPX BY 12Z SAT...MODELS SHOW MOST IMPRESSIVE H7-3 QVECTOR CNVGC/HIER PW AND H85-5 RH CROSSING MAINLY THE WRN ZNS INTO WI. ETA INDICATES SHARP GRADIENT OF KINX FM LO 30S ALG WI BORDER TO LO 20S AT ERY ON 12Z SAT. GIVEN MODEL TRENDS AND FCST LACK OF DYNAMICS TO SATURATE DRY MID LVLS ARRIVING TDAY... HAVE OPTED TO REMOVE PCPN MENTION FM FAR E. ALTHOUGH THERE IS CURRENTLY ONLY SCT SHRA AHD OF SHRTWV...WL BUMP UP POPS TO LIKELY OVR WI BORDER ZNS GIVEN AVN/ETA FCST H85-5 RH TO 80 PCT AND KINX OVR 30. BUT INITIAL DRYNESS OF AIRMASS AND LACK OF SGNFT ISENTROPIC LIFT SUGS CATEGORICAL POPS FCST BY AVN MOS MAY BE ON THE HI SIDE. HAVE GONE ABV MOS FCST FOR MINS GIVEN OBSVD DWPTS WELL INTO 50S IN CNTRL CAN. AS SHRTWV CONTS S ON SAT AND H7-3 QVECTOR CNVGC EXITS...XPCT PCPN TO END N TO S. AVN MOST AGGRESSIVE AT DRYING FM THE NE AS SFC HI PRES BLDS ACRS ONTARIO UNDER UPR RDGING IN SCNTRL CAN. CONSIDERING MODEL TRENDS...PREFER AVN FCST AND THINK ETA HOLDING ON TO LLVL MSTR TOO LONG (DWPT 65 AT IMT SAT AFTN) GIVEN XPCTD NELY WND WITH SHRTWV GOING SO FAR S. USED MIX OF MAV/FWC MOS FOR MAX WITH TENDENCY TO GO LOWEST ON TEMPS RELATIVE TO MOS IN PLACES WITH MOST CLD COVER XPCTD. DRY WX SAT NGT WITH UPR RDGING AND H85-3 QVECTOR DVGC. NR MOS FCST FOR MINS. COORDINATED WITH APX/GRB. .MQT...NONE. KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 103 AM EDT FRI AUG 17 2001 DISC... .BOTTOM LINE...AT LEAST SCT CONVECTION TDA. .PROBLEM OF THE DAY...HOW POTENT WL THAT CONVECTION BE? .SYNOPSIS...S/W TROAL WRN SHR HDSBAY SWD TO NRN PLNS KICKING/WKNG A VANGUARD TROAL OVR CNTRL GRTLKS QUICKLY ENE DOWN ST LAW VLY LTR TDA /TNGT. ERN TROAL MOVS SO QUICKLY THAT DRIER AIR MOVS INTO CWA IN ULVLS TAFTN...AND DYNAMICS RMN WK THRUT THE DAY. WRN TROAL DROPS TO VCNTY SWRN GRTLKS LT SAT WHILE ITSFYG. WMFNT MAY MOV THRU ERN NY TMRNG FOLLOWED BY CDFNT OR OCFNT TAFTN/TEVE. ASSOCD LOPRES MOVS THRU ONT/QUE PROVINCES TDA/TNGT...TO VCNTY SRN LABRADOR SAT. USTBL AMS WL BE OVR CWA TDA...MORE STBL AIR TAKES HOLD TNGT...W WK SFC RDG ERN GRTLKS SAT. .MDLS...META/ETA/AVN/RAFS/GEM RGNL AND GLOBAL/SUNYSB MM5 MDLS WERE ALL EXAMINED. ALL FCST AT LEAST A LTL PCPN OVR CWA TDA/TNGT. GENLLY MDL QPF IS QUITE LGT. HWR...MM5 SUNYSB HAS INVOF HLF/3 QTR INCH CTKLS...PEAK RNFL OCRS LT TMRNG...GOING DRY THRUT CWA BTWN 21Z/00Z. META SUGGESTS THAT H2/H3 DVRGNC ASSOCD W WMAX WL PEAK TWD NOON FM LWR CTSKLS INTO SWRN NEW ENG...THEN WKN GO THE POINT OF BCMG CONVERGENT BY THE TIME SFC FNT ARRIVES IN HDSVLY. THIS IS NOT A GOOD SIGN FOR WDSPRD DP CONVECTION BFR FROPA. HWR...META BL CAPES INVOF 1500/1600 J/KG TAFTN IN ADVANCE OF CDFNT. THIS IS A GOOD SIGN. GEM RGNL CAPE FCST NOT AS IMPRESSIVE...INVOF 500/1000 ACRS CWA FOR A PORTION OF THE AFTN. TAFTN IN KALY/S CWA...ULVL WMAX INVOF 100 KTS...LLVL WMAX INVOF 30 KTS. STGST LLVL WND IS ERY TMRNG. META HLCTY FCST INVOF 100 WHILE GEM A BIT HIR AT 150+. RAFS/GEM GLOBAL HAVE MOST WDSPRD PCPN SAT...NWRN CWA. ETA/META/AVN ARE DRY...WHILE GEM RGNL SPITS OUT A LTL PCPN N/W. ETA/AVN/GEM GLOBAL FCST DRY SAT NGT. AVN...HAS LOPRES CHARGING EWD ACRS OH VLY SUN AND BRINGS SGFNT PCPN INTO MUCH OF CWA DURG AFTN. GEM GLOBAL FCSTS WDSPRD LGT PCPN SUN. .SHORT TERM...SHWRS/TSTMS ASSOCD W MOISTENING AMS ALG WRMFNT HEADING INTO CWA ATTM. RUC SHOWS GRTST INSTBLTY ALG CNTRL SRN TIER WHERE LGTNG STRIKES HAVE BEEN MOST NMRS. RUC ALSO INDC WDSPRD ULVL DVRGNC TO THE W OF CWA. MACHINE POPS ARE IN CHC OR LOW LKLKY CAT TDA...NOT TOO MUCH DIFFERENT THAN GOING FCST...AND WL LKLY STAY CLOSE TO CURRENT FCST. SPC HAD US HILITED IN DAY2 SWO PROD. SOME ELEMENTS FOR SLGT RISK SVR ARE THERE...OTHERS ARE NOT. WL AWAIT NEW DAY1 SWO BEFORE GOING W ENHANCED WORDING IN ZONES/SPS. MM5 FCST SNDGS SAY MAXT 75/80 TAFTN...MACHINE GENLLY HIR. WL GO W MAXT IN U70S/L80S. .LONG TERM...CDFNT WL BE E OF CWA FOR MUCH OF NGT. ULVL TROF MOVG SO FAST THAT XPC DYNAMICS TO BE UNFAVORABLE TO CONT W CONVECTION AFT 00Z. HWR...ENUF LLVL INSTBLTY INDC N/W OF CAP DIST TO CAUSE SOME LGT SHWRS. THE PREV FCST HAD THIS INDC AND WL STICK W IT. WL LWR MIN/T FM PREV FCST INTO U50S IN NWRN ZNS TNGT...OTRW...NO CHG. SAT SHOULD BE MNLY DRY. HWR...SINCE PCPN INDC IN NWRN ZNS BY PREV FCST...AND SOME MDLS HAVE A LTL THERE...WL CONT W LOW CHC SHWRS ...NW. COULD BE SUBSTANTIAL AMT OF CI W DP TROAL WRN GRTLKS... SPILLING EWD INTO CWA. MM5 FCST SNDGS SUGGEST MAXT SAT WL BE A LTL LWR THAN TDA. H8 TEMP IS A DEG OR TWO LWR...BUT MAY BE MORE SS. .XTND FCST...MDLS SUGGEST DRY SAT NGT AND PCPN SUN...PER CURRENT FCST. LATEST RUN OF GEM GLOBAL/AVN FCST TROAL/SFC LOPRES INVCNTY MON SO CONT W CHC SHWRS PER PREV XTND...AND GO DRY TUE AS SYS APRS TO BE PROGRESSIVE AND DRIER/MORE STBL AMS XPC TO TAKE HOLD FOR MIDWK PD. SEE LTL REASON TO TINKER W GOING XTND FCST. .ALY...NY ERN/VT EXTRM SRN/MA EXTRM WRN/CT NW...NONE. KHH ny WEST CENTRAL AND SOUTHWEST FLORIDA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL 941 AM EDT FRI AUG 17 2001 ITS FRIDAY AND ALL WEEK LONG WE HAVE HAD A RIDGE...AND THEREFORE BASICALLY BENIGN WEATHER PARKED OVER US. TODAY IS NO DIFFERENT. AGAIN THERE ARE LITTLE NUANCES...A LITTLE MORE SUBSIDENCE TODAY AS SHOWN BE THIS MORNINGS SOUNDING. 500MB HEIGHTS ARE 595 PLUS... SURFACE PRESSURE ARE A CONSIDERABLY HIGHER...PWATS DOWN TO 1.78... ALTHOUGH US AND EYW ARE THE ONLY SOUNDINGS SHOWING SUCH PRONOUNCED SUBSIDENCE. THIS MORNINGS RADAR IS ECHO FREE...ANOTHER SIGN. THE MESOETA AND RUC SHOW THIS SUBSIDENCE WEAKENING A BIT AS THE DAY PROGRESSES. ONCE AGAIN THE MIDNIGHT SHIFT HIT THIS ON THE HEAD WITH THEIR FORECAST AND I PLAN NO CHANGES. .TBW...NONE. SOBIEN fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1119 AM EDT FRI AUG 17 2001 STRONG SFC LOW IS NOW CENTERED NE OF LOWER MI OVER ONTARIO. SFC-500 MB CYCLONIC FLOW...1000-500 MB RH OF 70-80 PCT AND MARGINAL INSTABILITY (CAPES OF 100-200 J/KG) CONTINUE TO PRODUCE LOW CLOUDS AND SCATTERED -SHRA ACROSS MUCH OF THE CWA LATE THIS MORNING. LATEST VSBL SATELLITE SHOWS CLEARING SKIES ACROSS WRN UPR MI AND WI AS FLOW BECOMES ANTICYCLONIC. MAIN ISSUE FOR THE AFTERNOON IS TIMING THE ENDING OF THE SCT -SHRA AND THE DECREASE IN LOW CLOUDS AS THE SFC LOW DEPARTS TO THE NE. LATEST RUC40 SEEMS TO HAVE A GOOD HANDLE ON THE BACK EDGE OF THE LOW CLOUD SHIELD...WHICH AT 15Z EXTENDS FROM ERN LAKE SUPERIOR THRU CENTRAL UPR MI AND THEN SOUTHWARD THRU THE LENGTH OF LAKE MI. EXTRAPOLATION OF THIS BACK EDGE POINTS TOWARD LOW CLOUDS AND LIGHT PRECIP LINGERING INTO EARLY AFTERNOON FOR PLACES SW OF A LINE FROM PLN TO GLR TO OSC...THEN SKIES BECOMING PARTLY SUNNY AS FLOW BECOMES INCREASINGLY ANTICYCLONIC AND LOW/MID LEVEL DRYING TAKES PLACE. PARTIAL CLEARING WILL HOLD OFF UNTIL LATE IN THE DAY FOR PLACES N OF THIS LINE IN ERN UPR AND FAR NE LOWER MI. WILL UPDATE FORECAST TO REFLECT THE TIMING MENTIONED ABOVE AND TO DECREASE AFTERNOON HIGH TEMPS IN LIGHT OF THE PROJECTED DELAY IN DECREASING CLOUDS. .APX...NONE. EME mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1105 AM EDT FRI AUG 17 2001 FCST CONCERN THIS AFTN IS HIGH TEMPS AND POTENTIAL OF SHRA OVER FAR W. WV IMAGERY SHOWS ONE STRONG SHORTWAVE DEPARTING THRU THE ERN LAKES WHILE UPSTREAM ANOTHER VIGOROUS SHORTWAVE WAS DROPPING S THRU MANITOBA INTO THE MEAN TROF POSITION. VIS IMAGERY SHOWS CLEARING PROGRESSING ACROSS FA THIS MORNING AS SHORTWAVE RIDGING MOVES EWD. CLEARING LINE RUNS FROM ABOUT KMQT TO KMNM AT 1430Z. ALREADY UPSTREAM...CLDS ADVANCING QUICKLY ACROSS NRN MN AHEAD OF NEXT SHORTWAVE WITH RADARS INDICATING SOME SCT SHRA AS WELL. TSRA SHOWING UP ALONG COLD FRONT IN SERN MANITOBA/SWRN ONTARIO. 12Z KINL SOUNDING SHOWS GOOD MOISTURE THRU MUCH OF THE LWR/MIDDLE TROPOSPHERE...AND K INDEX IS 34. DEEP MOISTURE RESULTING IN SCT SHRA AS THE AREA ACROSS MN/ONTARIO/MANITOBA IS IN DIFFLUENT REGION ASSOCIATED WITH THE LEFT EXIT OF 80KT 300MB JET EXTENDING FROM HUDSON BAY TWD DAKOTAS PER 12Z RAOBS. 12Z RUC ALSO SHOWS BULLSEYE OF QVEC CONVERGENCE ACROSS THAT AREA. ORIENTATION OF UPPER JET DIRECTED TO THE SSW AND WELL W OF FA SUGGESTS THAT MAIN SYNOPTIC FORCING FOR UVM WILL BE SLOW TO PROGRESS EWD AS IT IS DIRECTED MORE TO THE S ACROSS MN THAN E TWD UPPER MI THIS AFTN. THUS...ALTHOUGH IT SEEMS SHRA ARE MAKING STEADY PROGRESS EWD ACROSS NRN MN...BELIEVE THESE SHRA WILL FALL APART AS THEY MOVE AWAY FROM GENESIS REGION INTO A MORE STABLE/DRIER AIRMASS OVER FA PER 12Z KGRB SOUNDING WHICH HAD PRONOUNCED SUBSIDENCE INVERSION. SO...WILL PULL MENTION OF LATE AFTN SHRA FROM FAR WRN FA. SEEMS LIKELY IT WILL BE EVENING HOURS BEFORE ANY SHRA MAKE IT AS FAR E AS KIWD. THERMAL TROF WITH 850MB TEMPS AROUND 9C ACROSS FA EARLY THIS AFTN COMBINED WITH SFC DWPTS 10-13C WILL LEAD TO SCT/BKN CU DEVELOPMENT. THIS WILL KEEP HIGH TEMPS FROM REACHING THEIR POTENTIAL. MIXING TO ABOUT 800MB ON KGRB SOUNDING AND RUC SOUNDINGS YIELDS HIGHS AT THE UPPER BOUND IN THE MID 70S FOR THOSE AREAS WHICH SEE MOST SUN AND ARE AWAY FROM LK SUPERIOR. THIS A BIT ABOVE WHAT TRAJECTORIES INDICATE. MAY MAKE A FEW MINOR DOWNWARD ADJUSTMENTS BASED ON THIS AND LATEST OBS/SATELLITE. .MQT...NONE. ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 1045 AM CDT FRI AUG 17 2001 TEMPERATURES IN FRONT OF AC/SC DECK OVER KANSAS HAS INCREASED TO ABOVE GUIDANCE TEMPS AND WILL LIKELY INCREASE TO NEAR 90 IN EXT SW MO...AND ALONG THE ARKANSAS BORDER WEST OF BRANSON. ELSEWHERE TEMPERATURES SHOULD BE IN THE MID TO UPPER 80S. LATEST RUC/MESOETA HAVE COMPLEX OF THUNDERSTORMS DEVELOPING OVER WEST CENTRAL MO AND MOVING IT SOUTHWARD INTO MORE UNSTABLE ATMOSPHERE THIS AFTN. WITH DEW POINTS INCREASING AND LAPS INFO INDICATING FURTHER INSTABILITY...WITH LIKELY HAVE A FEW SEVERE STORMS THIS AFTN IN AREA OF MAX HEATING IN SW MO. ZONES SHOULD BE SENT BY 11 AM. .SGF... MO...NONE. KS...NONE. JLT mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 958 AM EDT FRI AUG 17 2001 PCPN MOVING THRU THIS MORNING...PRETTY MUCH AS EXPECTED...WITH LITTLE LIGHTNING ACTIVITY NOTED. THE WEAK COLD FRONT HAS PUSHED THRU THE NW HALF OF THE FORECAST AREA...WITH WIND SHIFT AND SLIGHTLY DRIER AIR WORKING IN PER SFC AND FORECAST SOUNDINGS. THINK THAT THE FRONTAL BOUNDARY WILL SLOW AND/OR STALL NEAR THE MOUNTAIN ZONES... WHERE RUC40 SOUNDINGS FOR THIS AFTERNOON INDICATE CAPES OF 1500 TO 2500 J/KG. WEAK CONVERGENCE SEEMS LIKELY AS WINDS BECOME LIGHT WESTERLY...SO I WILL KEEP SLIGHT CHANCE POPS GOING FOR OUR MTN ZONES THIS AFTERNOON (WHICH IS IN LINE WITH DAY ONE CONVECTIVE OUTLOOK). OTHERWISE...EXPECT SOME GOOD AMOUNTS OF SUNSHINE TO BREAK OUT AND WE SHOULD REACH FORECASTED HIGHS AT MOST LOCATIONS. I MAY MAKE SLIGHT ADJUSTMENT DOWNWARD FOR EXTRM NE TN/SWRN VA GROUP...AND CHECK RANGES IN MTN ZONES. UPDATED ZONES BY AROUND 1030 AM OR SO. .MRX... NC...NONE. TN...NONE. VA...NONE. TG tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG, VA 945 AM EDT FRI AUG 17 2001 AM UPDATE PLANNED... THIS AM'S SOUNDING SHOWING PLENTY OF MOISTURE AHEAD OF THE FRONT...BUT MARGINAL INSTABILITY AND LITTLE IN THE WAY OF SHEAR. BAND SCTD -SHRA XTNDS NE-SW ACRS WRN THIRD FA...MAKING SLOW PROGRESS EAST. 12Z SFC ANALYSIS PLACES FRONTAL SYSTEM INTO WESTERN FA...ALONG WV-VA BRDR...THRU FAR WEST VA AND INTO ERN TN. NOT A LOT OF PUSH BEHIND FRONT...SO THINKING IS IT WILL TAKE REST OF MORNING AND PART OF AFTN TO MOVE ACRS MTNS. CONSEQUENCE HERE IS THAT MAY NEED TO BEEF UP WORDING ON CLD COVER FOR THIS AFTN. ALSO...LACK OF GOOD NW FLOW BEHIND FRONT UNTIL EVE HRS...AS PER RUC...AND DEEPER MOISTURE THAN ANTICIPATED OVER LOWER OHIO VLY...A`LA WATER VAPOR LOOP... INDICATES NO REAL PRONOUNCED DRYING BEHIND SYSTEM. BEST CHC OF TSRA STILL LOOKS TO BE EASTERN ZONES LATE AFTN-EVE HRS. TEMPS MAY ALSO NEED LWRG A CAT OVER WESTERN GROUPS WITH PROLONGED CLD COVER...WILL DECIDE AFTER 10 AM ON THESE. .RNK... NC...NONE. VA...NONE. WV...NONE. MG va AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 150 PM CDT FRI AUG 17 2001 18Z MOSAIC OF KSGF/KEAX RADARS SHOWS SCATTERED THUNDERSTORMS DEVELOPING OVER SW MISSOURI...WITH MORE GENERAL RAIN COVERAGE OVER WEST CENTRAL MISSOURI. THIS PRECIP IS ASSOCIATED WITH A 500 MB SHORTWAVE TROUGH MOVING EAST ACROSS KANSAS. ANOTHER STRONGER 500 MB SHORTWAVE IS MOVING SOUTHWARD TOWARD THE MINNESOTA/CANADIAN BORDER. THE PRECIP FORECAST OVER THE NEXT 48 HOURS HINGES ON THESE TWO SHORTWAVES. ETA/NGM/AVN AGREE THAT THE CANADIAN SHORTWAVE WILL BECOME THE DOMINANT SYSTEM AS IT SWINGS SOUTHEAST INTO THE MID MISSISSIPPI VALLEY BY SATURDAY NIGHT. THE INITIAL SHORTWAVE...NOW LOCATED OVER KANSAS...IS PROGGED TO DAMPEN OUT AS IT MOVES EAST. AVN IS SLOWEST TO WEAKEN THIS WAVE...AND THIS IS REFLECTED IN THE HIGH AVN MOS POPS FOR TONIGHT. RUC/ETA BOTH INDICATE 850 MB LEVEL WILL STEADILY MOISTEN AND DESTABILIZE FROM WEST TO EAST TONIGHT. SCATTERED SHOWERS/ELEVATED THUNDERSTORMS WILL OVERSPREAD MUCH OF THE FORECAST AREA TONIGHT. BEST COVERAGE WILL BE IN THE WEST. AFTER THE PASSAGE OF THE LEAD SHORTWAVE SATURDAY MORNING...CLOUDS MAY BREAK FOR A WHILE. ANOTHER MORE SIGNIFICANT ROUND OF CONVECTION IS EXPECTED DURING THE AFTERNOON AND EVENING AS THE STRONGER SHORTWAVE APPROACHES. PARAMETERS APPEAR TO BE IN PLACE FOR SOME THREAT OF SEVERE...WITH MODERATELY STRONG WINDS ALOFT AND SURFACE DEW POINTS AROUND 70. MODELS AGREE SURFACE TROUGH/COLD FRONT WILL CROSS THE LOWER OHIO VALLEY AROUND 06Z SUNDAY...AND BE EAST OF THE FORECAST AREA BY 12Z SUNDAY. ON SUNDAY...SOME LINGERING SHOWERS ARE POSSIBLE IN THE EASTERN COUNTIES...MAINLY IN THE MORNING. SOME WRAPAROUND LOW LEVEL CLOUDINESS WILL PERSIST UNDER COLDER AIR ALOFT. COOLER AND LESS HUMID AIR WILL BE THE MAIN STORY. FOR TEMPERATURES...AVN/NGM MOS ARE SIMILAR AND WILL FOLLOW. EXTENDED FORECAST... 12Z AVN SUPPORTS LAST NIGHTS MRF TREND OF BUILDING A MID LEVEL RIDGE OVER THE FORECAST AREA BY MID WEEK. THIS WILL RESULT IN A GRADUAL RETURN TO SUMMERTIME HEAT...WITH AN EXTENDED PERIOD OF DRY WEATHER. .PAH...NONE. MY ky SOUTH CENTRAL NEBRASKA/NORTH CENTRAL KANSAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 210 PM CDT FRI AUG 17 2001 QUESTION FOR THE DAY IS WHETHER CONV WILL FIRE LT THIS AFTN INTO THIS EVENING. 19Z SFC MAP SHOWS PREFNTL TROUGH ROUGHLY ALG A ONL TO MCK LINE IN REFLECTION OF UPR TROF DIGGING ACRS SD ATTM. PLUME OF STEEP MID LVL LAPSE RATES AHD OF THIS FTR COMBINED WITH INCREASING LOW LVL WAA AS WINDS CONT TO BACK AHD OF UPR TROF...ALL LEADING TO A SMALL BUT PERSISTENT BAND OF MID LVL CLDS/SHOWERS FM ODX BACK TO W TO BFF. DESTABILIZATION CONTS UNABATED ACRS MOST OF CWA WITH 18Z TEMPS RUNNING WELL ABV 12Z GUIDANCE NUMBERS AND DEWPOINTS WELL INTO MID 60S...ALL LEADING TO SIG INSTABILITY THIS AFTN. 12Z ETA/NGM ALG WITH LATEST RUC ALL POINTING TO CONV INITIATION ALG SFC TROF ARND 21Z ALG A OLU TO EAR LINE. BELIEVE WITH MOST LOCALES SITTING AT CONV TEMP ALREADY AND DECENT SFC CVRG ALG BNDRY ESP FM GRI EAST...THINGS SHLD POP. WOULD XPC ACTIVITY TO LINGER INTO MID EVENING EAST BEFORE PRIMARY COLD FNT ASSOCD/W SIG UPR TROF OVR MANITOBA SWEEPS PRECIP S AND E. CAA ASSOCD/W COLD FNT LAGGING THIS AFTN AND IS NOT PROGGED INTO CWA UNTIL SAT AM SO XPC TEMPS TONIGHT SIMILAR TO LAST NIGHT. HIGHS SAT WILL BE TRICKY GIVEN PROGGED EARNEST LOW LVL CAA OFFSET BY INSOLATION. GOING NUMBERS IN THE BALLPARK. BUILDING RIDGE SAT NIGHT WILL LEAD TO COOL NIGHT BUT WARMUP COMMENCES SUN AS FLW SHIFT S AND UPR RIDGE BEGINS TO BUILD AHD OF UPSTREAM TROF OVR SW CANADA. IN THE EXTNDD...MED RANGE MODELS PRETTY SIMILAR WITH EVOLUTION OF AMPLIFYING UPR TROF ALG THE W COAST AND EWD SHIFT/FLATTENING OF UPR RIDGE INTO THE PLAINS. THIS WOULD FAVR PERSISTENT LEE SIDE TROF AND NIGHTLY MCS CLUSTERS TIED TO NOCTURNAL JET. AT THIS POINT...ITS FRIVOLOUS TO TRY AND PIN ANYTHING DOWN AND WILL BROAD-BRUSH TUE-THU TIME FRAME. HWVR MORE CONFIDENT THAT AS RIDGE SHIFTS E...AND NAO CONTS IN INCREASINGLY POSITIVE PHASE...THAT RTN TO ABV NORMAL TEMPS IN STORE FOR CWA. .GID...NONE. TEH ne TEXAS/OKLAHOMA PANHANDLES FORECAST DISCUSSION NATIONAL WEATHER SERVICE AMARILLO TX 1139 AM CDT FRI AUG 17 2001 UPDATED ZNS TO TAKE OUT MORNING WORDING. LEFT ISOLD COVERAGE TERMS IN NE ZNS SINCE LATEST RUC PAINTING QUITE A BIT OF PRECIP IN THAT AREA THIS AFTN. WEAK SHRTWV NOTED ON MORNING UA/PROFILER ACROSS WRN KS WILL SLIDE E SKIRTING NE ZNS THIS AFTN AND WITH OUTFLOW FM OVERNIGHT CONVECTION AND UNCAPPED ENVIRONMENT MODEL OUTPUT SEEMS REASONABLE. ELSWHR...TOO EARLY YET TO TELL WHO WILL BE LUCKY ONES TODAY TO SEE ISOLD DOWNPOURS...YET ATMOSPHERE STILL VERY MOIST WITH PWS 140 PERCENT NORMAL. WITH AFTN HEATING AND STEEP LAPSE RATES... CAPES SHOULD EXCEED 1500 J/KG SO SOME SMALL HAIL POSSIBLE AGAIN. .AMA... TX...NONE. OK...NONE. COBB tx