Several pieces of guidance show the
possibility of the low stalling, or even backbuilding a bit,
overnight, which would prolong the duration of heavy precip.
The overall QPF forecast remains consistent with the previous shift,
with a maximum of 4-6", perhaps locally higher, forecast over east
central Connecticut and central Massachusetts. HREF ensemble
consistency has been rather remarkable over the last few runs, with
little to no wobble in the anticipated axis of heaviest
precipitation and consistency in the 24 hour LPMM (best reasonable
guess for maximum precip potential) showing a widespread swath of 5-
7" across the aforementioned region. While it may seem
insignificant, both the CMC and GEFS ensembles show bullseyes of
10-30% probabilities of 4" of QPF or greater over
Tolland/Windham County Connecticut; which is marked as a
considerable signal for significant precip in terms of global
guidance. Thus, with all things above considered, collaborated
with WPC and our neighboring WFOs to upgrade the Excessive
Rainfall Outlook to MODERATE, to highlight the increased
potential for flash flooding.